Rheumatology

Knee osteoarthritis (OA) affects almost 9.3 million adults in the US and accounts for $27 billion in annual health care expenses.^1,2 Due to the increasing cost of health care and an aging population, there has been renewed interest in establishing criteria for nonarthroplasty treatment of knee OA.

In 2013, using the RAND/UCLA Appropriateness method, the American Academy of Orthopaedic Surgeons (AAOS) developed an appropriate use criteria (AUC) for nonarthroplasty management of primary OA of the knee, based on orthopaedic literature and expert opinion.³ Interventions such as activity modification, weight loss, prescribed physical therapy, nonsteroidal anti-inflammatory drugs, tramadol, prescribed oral or transcutaneous opioids, acetaminophen, intra-articular corticosteroids, hinged or unloading knee braces, arthroscopic partial menisectomy or loose body removal, and realignment osteotomy were assessed. An algorithm was developed for 576 patients scenarios that incorporated patient-specific, prognostic/predictor variables to assign designations of “appropriate,” “may be appropriate,” or “rarely appropriate,” to treatment interventions.^4,5 An online version of the algorithm (orthoguidelines.org) is available for physicians and surgeons to judge appropriateness of nonarthroplasty treatments; however, it is not intended to mandate candidacy for treatment or intervention.

Clinical evaluation of the AAOS AUC is necessary to determine how treatment recommendations correlate with current practice. A recent examination of the AAOS Appropriateness System for Surgical Management of Knee OA found that prognostic/predictor variables, such as patient age, OA severity, and pattern of knee OA involvement were more heavily weighted when determining arthroplasty appropriateness than was pain severity or functional loss.⁶ Furthermore, non-AAOS AUC prognostic/predictor variables, such as race and gender, have been linked to disparities in utilization of knee OA interventions.^7-9 Such disparities can be costly not just from a patient perceptive, but also employer and societal perspectives.¹⁰

The Department of Veterans Affairs (VA) health care system represents a model of equal-access-to care system in the US that is ideal for examination of issues about health care utilization and any disparities within the AAOS AUC model and has previously been used to assess utilization of total knee arthroplasty.⁹ The aim of this study was to characterize utilization of the AAOS AUC for nonarthroplasty treatment of knee OA in a VA patient population. We asked the following questions: (1) What variables are predictive of receiving a greater number of AAOS AUC evaluated nonarthroplasty treatments? (2) What variables are predictive of receiving “rarely appropriate” AAOS AUC evaluated nonarthroplasty treatment? (3) What factors are predictive of duration of nonarthroplasty care until total knee arthroplasty (TKA)?

Methods

The institutional review board at the Louis Stokes Cleveland VA Medical Center in Ohio approved a retrospective chart review of nonarthroplasty treatments utilized by patients presenting to its orthopaedic section who subsequently underwent knee arthroplasty between 2013 and 2016. Eligibility criteria included patients aged ≥ 30 years with a diagnosis of unilateral or bilateral primary knee OA. Patients with posttraumatic OA, inflammatory arthritis, and a history of infectious arthritis or Charcot arthropathy of the knee were excluded. Patients with a body mass index (BMI) > 40 or a hemoglobin A_1c > 8.0 at presentation were excluded as nonarthroplasty care was the recommended course of treatment above these thresholds.

Data collected included race, gender, duration of nonarthroplasty treatment, BMI, and Kellgren-Lawrence classification of knee OA at time of presentation for symptomatic knee OA.¹¹ All AAOS AUC-evaluated nonarthroplasty treatments utilized prior to arthroplasty intervention also were recorded (Table 1). 

Statistical Analysis

Statistical analysis was completed with GraphPad Software Prism 7.0a (La Jolla, CA) and Mathworks MatLab R2016b software (Natick, MA). Univariate analysis with Student t tests with Welch corrections in the setting of unequal variance, Mann-Whitney nonparametric tests, and Fisher exact test were generated in the appropriate setting. Multivariable analyses also were conducted. For continuous outcomes, stepwise multiple linear regression was used to generate predictive models; for binary outcomes, binomial logistic regression was used.

Factors analyzed in regression modeling for the total number of AAOS AUC evaluated nonarthroplasty treatments utilized and the likelihood of receiving a rarely appropriate treatment included gender, race, function-limiting pain, range of motion (ROM), ligamentous instability, arthritis pattern, limb alignment, mechanical symptoms, BMI, age, and Kellgren-Lawrence grade. Factors analyzed in timing of TKA included the above variables plus the total number of AUC interventions, whether the patient received an inappropriate intervention, and average appropriateness of the interventions received. Residual analysis with Cook’s distance was used to identify outliers in regression. Observations with Cook’s distance > 3 times the mean Cook’s distance were identified as potential outliers, and models were adjusted accordingly. All statistical analyses were 2-tailed. Statistical significance was set to P ≤ .05 for all outputs.

Results

In the study, 97.8% of participants identified as male, and the mean age was 62.8 years (Table 3). 

Appropriate Use Criteria Interventions

Patients received a mean of 5.2 AAOS AUC evaluated interventions before undergoing arthroplasty management at a mean of 32.3 months (range 2-181 months) from initial presentation. The majority of these interventions were classified as either appropriate or may be appropriate, according to the AUC definitions (95.1%). Self-management and physical therapy programs were widely utilized (100% and 90.1%, respectively), with all use of these interventions classified as appropriate.

Hinged or unloader knee braces were utilized in about half the study patients; this intervention was classified as rarely appropriate in 4.4% of these patients. Medical therapy was also widely used, with all use of NSAIDs, acetaminophen, and tramadol classified as appropriate or may be appropriate. Oral or transcutaneous opioid medications were prescribed in 14.3% of patients, with 92.3% of this use classified as rarely appropriate. Although the opioid medication prescribing provider was not specifically evaluated, there were no instances in which the orthopaedic service provided an oral or transcutaneous opioid prescriptions. Procedural interventions, with the exception of corticosteroid injections, were uncommon; no patient received realignment osteotomy, and only 12.1% of patients underwent arthroscopy. The use of arthroscopy was deemed rarely appropriate in 72.7% of these cases.

Factors Associated With AAOS AUC Intervention Use

There was no difference in the number of AAOS AUC evaluated interventions received based on BMI (mean [SD] BMI < 35, 5.2 [1.0] vs BMI ≥ 35, 5.3 [1.1], P = .49), age (mean [SD] aged < 60 years, 5.4 [1.0] vs aged ≥ 60 years, 5.1 [1.2], P = .23), or Kellgren-Lawrence arthritic grade (mean [SD] grade ≤ 2, 5.5 [1.0] vs grade > 2, 5.1 [1.1], P = .06). These variables also were not associated with receiving a rarely appropriate intervention (mean [SD] BMI < 35, 0.27 [0.5] vs BMI > 35, 0.2 [0.4], P = .81; aged > 60 years, 0.3 [0.5] vs aged < 60 years, 0.2 [0.4], P = .26; Kellgren-Lawrence grade < 2, 0.4 [0.6] vs grade > 2, 0.2 [0.4], P = .1).

Regression modeling to predict total number of AAOS AUC evaluated interventions received produced a significant model (R² = 0.111, P = .006). The presence of ligamentous instability (β coefficient, -1.61) and the absence of mechanical symptoms (β coefficient, -0.67) were negative predictors of number of AUC interventions received. Variance inflation factors were 1.014 and 1.012, respectively. Likewise, regression modeling to identify factors predictive of receiving a rarely appropriate intervention also produced a significant model (pseudo R²= 0.06, P = .025), with lower Kellgren-Lawrence grade the only significant predictor of receiving a rarely appropriate intervention (odds ratio [OR] 0.54; 95% CI, 0.42 -0.72, per unit increase).

Timing from presentation to arthroplasty intervention was also evaluated. Age was a negative predictor (β coefficient -1.61), while positive predictors were reduced ROM (β coefficient 15.72) and having more AUC interventions (β coefficient 7.31) (model R²= 0.29, P = < .001). Age was the most significant predictor. Variance inflations factors were 1.02, 1.01, and 1.03, respectively. Receiving a rarely appropriate intervention was not associated with TKA timing.

Discussion

This single-center retrospective study examined the utilization of AAOS AUC-evaluated nonarthroplasty interventions for symptomatic knee OA prior to TKA. The aims of this study were to validate the AAOS AUC in a clinical setting and identify predictors of AAOS AUC utilization. In particular, this study focused on the number of interventions utilized prior to knee arthroplasty, whether interventions receiving a designation of rarely appropriate were used, and the duration of nonarthroplasty treatment.

Patients with knee instability used fewer total AAOS AUC evaluated interventions prior to TKA. Subjective instability has been reported as high as 27% in patients with OA and has been associated with fear of falling, poor balance confidence, activity limitations, and lower Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical function scores.¹² However, it has not been found to correlate with knee laxity.¹³ Nevertheless, significant functional impairment with the risk of falling may reduce the number of nonarthroplasty interventions attempted. On the other hand, the presence of mechanical symptoms resulted in greater utilization of nonarthroplasty interventions. This is likely due to the greater utilization of arthroscopic partial menisectomy or loose body removal in this group of patients. Despite its inclusion as an AAOS AUC evaluated intervention, arthroscopy remains a contentious treatment for symptomatic knee pain in the setting of OA.^14,15

For every unit decrease in Kellgren-Lawrence OA grade, patients were 54% more likely to receive a rarely appropriate intervention prior to knee arthroplasty. This is supported by the recent literature examining the AAOS AUC for surgical management of knee OA. Riddle and colleagues developed a classification tree to determine the contributions of various prognostic variables in final classifications of the 864 clinical vignettes used to develop the appropriateness algorithm and found that OA severity was strongly favored, with only 4 of the 432 vignettes with severe knee OA judged as rarely appropriate for surgical intervention.⁶

Our findings, too, may be explained by an AAOS AUC system that too heavily weighs radiographic severity of knee OA, resulting in more frequent rarely appropriate interventions in patients with less severe arthritis, including nonarthroplasty treatments. It is likely that rarely appropriate interventions were attempted in this subset of our study cohort based on patient’s subjective symptoms and functional status, both of which have been shown to be discordant with radiographic severity of knee OA.¹⁶

Oral or transcutaneous prescribed opioid medications were the most frequent intervention that received a rarely appropriate designation. Patients with preoperative opioid use undergoing TKA have been shown to have a greater risk for postoperative complications and longer hospital stay, particularly those patients aged < 75 years. Younger age, use of more interventions, and decreased knee ROM at presentation were predictive of longer duration of nonarthroplasty treatment. The use of more AAOS AUC evaluated interventions in these patients suggests that the AAOS AUC model may effectively be used to manage symptomatic OA, increasing the time from presentation to knee arthroplasty.

Interestingly, the use of rarely appropriate interventions did not affect TKA timing, as would be expected in a clinically effective nonarthroplasty treatment model. The reasons for rarely appropriate nonsurgical interventions are complex and require further investigation. One possible explanation is that decreased ROM was a marker for mechanical symptoms that necessitated additional intervention in the form of knee arthroscopy, delaying time to TKA.

Limitations

There are several limitations of this study. First, the small sample size (N = 90) requires acknowledgment; however, this limitation reflects the difficulty in following patients for years prior to an operative intervention. Second, the study population consists of veterans using the VA system and may not be reflective of the general population, differing with respect to gender, racial, and socioeconomic factors. Nevertheless, studies examining TKA utilization found, aside from racial and ethnic variability, patient gender and age do not affect arthroplasty utilization rate in the VA system.¹⁷

Additional limitations stem from the retrospective nature of this study. While the Computerized Patient Record System and centralized care of the VA system allows for review of all physical therapy consultations, orthotic consultations, and medications within the VA system, any treatments and intervention delivered by non-VA providers were not captured. Furthermore, the ability to assess for confounding variables limiting the prescription of certain medications, such as chronic kidney disease with NSAIDs or liver disease with acetaminophen, was limited by our study design.

Although our study suffers from selection bias with respect to examination of nonarthroplasty treatment in patients who have ultimately undergone TKA, we feel that this subset of patients with symptomatic knee OA represents the majority of patients evaluated for knee OA by orthopaedic surgeons in the clinic setting. It should be noted that although realignment osteotomies were sometimes indicated as appropriate by AAOS AUC model in our study population, this intervention was never performed due to patient and surgeon preference. Additionally, although it is not an AAOS AUC evaluated intervention, viscosupplementation was sporadically used during the study period; however, it is now off formulary at the investigation institution.

Conclusion

Our study suggests that patients without knee instability use more nonarthroplasty treatments over a longer period before TKA, and those patients with less severe knee OA are at risk of receiving an intervention judged to be rarely appropriate by the AAOS AUC. Such interventions do not affect timing of TKA. Nonarthroplasty care should be individualized to patients’ needs, and the decision to proceed with arthroplasty should be considered only after exhausting appropriate conservative measures. We recommend that providers use the AAOS AUC, especially when treating younger patients with less severe knee OA, particularly if considering opiate therapy or knee arthroscopy.

Acknowledgments
The authors would like to acknowledge Patrick Getty, MD, for his surgical care of some of the study patients. This material is the result of work supported with resources and the use of facilities at the Louis Stokes Cleveland VA Medical Center in Ohio.

Knee osteoarthritis (OA) affects almost 9.3 million adults in the US and accounts for $27 billion in annual health care expenses.^1,2 Due to the increasing cost of health care and an aging population, there has been renewed interest in establishing criteria for nonarthroplasty treatment of knee OA.

In 2013, using the RAND/UCLA Appropriateness method, the American Academy of Orthopaedic Surgeons (AAOS) developed an appropriate use criteria (AUC) for nonarthroplasty management of primary OA of the knee, based on orthopaedic literature and expert opinion.³ Interventions such as activity modification, weight loss, prescribed physical therapy, nonsteroidal anti-inflammatory drugs, tramadol, prescribed oral or transcutaneous opioids, acetaminophen, intra-articular corticosteroids, hinged or unloading knee braces, arthroscopic partial menisectomy or loose body removal, and realignment osteotomy were assessed. An algorithm was developed for 576 patients scenarios that incorporated patient-specific, prognostic/predictor variables to assign designations of “appropriate,” “may be appropriate,” or “rarely appropriate,” to treatment interventions.^4,5 An online version of the algorithm (orthoguidelines.org) is available for physicians and surgeons to judge appropriateness of nonarthroplasty treatments; however, it is not intended to mandate candidacy for treatment or intervention.

Clinical evaluation of the AAOS AUC is necessary to determine how treatment recommendations correlate with current practice. A recent examination of the AAOS Appropriateness System for Surgical Management of Knee OA found that prognostic/predictor variables, such as patient age, OA severity, and pattern of knee OA involvement were more heavily weighted when determining arthroplasty appropriateness than was pain severity or functional loss.⁶ Furthermore, non-AAOS AUC prognostic/predictor variables, such as race and gender, have been linked to disparities in utilization of knee OA interventions.^7-9 Such disparities can be costly not just from a patient perceptive, but also employer and societal perspectives.¹⁰

The Department of Veterans Affairs (VA) health care system represents a model of equal-access-to care system in the US that is ideal for examination of issues about health care utilization and any disparities within the AAOS AUC model and has previously been used to assess utilization of total knee arthroplasty.⁹ The aim of this study was to characterize utilization of the AAOS AUC for nonarthroplasty treatment of knee OA in a VA patient population. We asked the following questions: (1) What variables are predictive of receiving a greater number of AAOS AUC evaluated nonarthroplasty treatments? (2) What variables are predictive of receiving “rarely appropriate” AAOS AUC evaluated nonarthroplasty treatment? (3) What factors are predictive of duration of nonarthroplasty care until total knee arthroplasty (TKA)?

Methods

The institutional review board at the Louis Stokes Cleveland VA Medical Center in Ohio approved a retrospective chart review of nonarthroplasty treatments utilized by patients presenting to its orthopaedic section who subsequently underwent knee arthroplasty between 2013 and 2016. Eligibility criteria included patients aged ≥ 30 years with a diagnosis of unilateral or bilateral primary knee OA. Patients with posttraumatic OA, inflammatory arthritis, and a history of infectious arthritis or Charcot arthropathy of the knee were excluded. Patients with a body mass index (BMI) > 40 or a hemoglobin A_1c > 8.0 at presentation were excluded as nonarthroplasty care was the recommended course of treatment above these thresholds.

Data collected included race, gender, duration of nonarthroplasty treatment, BMI, and Kellgren-Lawrence classification of knee OA at time of presentation for symptomatic knee OA.¹¹ All AAOS AUC-evaluated nonarthroplasty treatments utilized prior to arthroplasty intervention also were recorded (Table 1). 

Statistical Analysis

Statistical analysis was completed with GraphPad Software Prism 7.0a (La Jolla, CA) and Mathworks MatLab R2016b software (Natick, MA). Univariate analysis with Student t tests with Welch corrections in the setting of unequal variance, Mann-Whitney nonparametric tests, and Fisher exact test were generated in the appropriate setting. Multivariable analyses also were conducted. For continuous outcomes, stepwise multiple linear regression was used to generate predictive models; for binary outcomes, binomial logistic regression was used.

Factors analyzed in regression modeling for the total number of AAOS AUC evaluated nonarthroplasty treatments utilized and the likelihood of receiving a rarely appropriate treatment included gender, race, function-limiting pain, range of motion (ROM), ligamentous instability, arthritis pattern, limb alignment, mechanical symptoms, BMI, age, and Kellgren-Lawrence grade. Factors analyzed in timing of TKA included the above variables plus the total number of AUC interventions, whether the patient received an inappropriate intervention, and average appropriateness of the interventions received. Residual analysis with Cook’s distance was used to identify outliers in regression. Observations with Cook’s distance > 3 times the mean Cook’s distance were identified as potential outliers, and models were adjusted accordingly. All statistical analyses were 2-tailed. Statistical significance was set to P ≤ .05 for all outputs.

Results

In the study, 97.8% of participants identified as male, and the mean age was 62.8 years (Table 3). 

Appropriate Use Criteria Interventions

Patients received a mean of 5.2 AAOS AUC evaluated interventions before undergoing arthroplasty management at a mean of 32.3 months (range 2-181 months) from initial presentation. The majority of these interventions were classified as either appropriate or may be appropriate, according to the AUC definitions (95.1%). Self-management and physical therapy programs were widely utilized (100% and 90.1%, respectively), with all use of these interventions classified as appropriate.

Hinged or unloader knee braces were utilized in about half the study patients; this intervention was classified as rarely appropriate in 4.4% of these patients. Medical therapy was also widely used, with all use of NSAIDs, acetaminophen, and tramadol classified as appropriate or may be appropriate. Oral or transcutaneous opioid medications were prescribed in 14.3% of patients, with 92.3% of this use classified as rarely appropriate. Although the opioid medication prescribing provider was not specifically evaluated, there were no instances in which the orthopaedic service provided an oral or transcutaneous opioid prescriptions. Procedural interventions, with the exception of corticosteroid injections, were uncommon; no patient received realignment osteotomy, and only 12.1% of patients underwent arthroscopy. The use of arthroscopy was deemed rarely appropriate in 72.7% of these cases.

Factors Associated With AAOS AUC Intervention Use

There was no difference in the number of AAOS AUC evaluated interventions received based on BMI (mean [SD] BMI < 35, 5.2 [1.0] vs BMI ≥ 35, 5.3 [1.1], P = .49), age (mean [SD] aged < 60 years, 5.4 [1.0] vs aged ≥ 60 years, 5.1 [1.2], P = .23), or Kellgren-Lawrence arthritic grade (mean [SD] grade ≤ 2, 5.5 [1.0] vs grade > 2, 5.1 [1.1], P = .06). These variables also were not associated with receiving a rarely appropriate intervention (mean [SD] BMI < 35, 0.27 [0.5] vs BMI > 35, 0.2 [0.4], P = .81; aged > 60 years, 0.3 [0.5] vs aged < 60 years, 0.2 [0.4], P = .26; Kellgren-Lawrence grade < 2, 0.4 [0.6] vs grade > 2, 0.2 [0.4], P = .1).

Regression modeling to predict total number of AAOS AUC evaluated interventions received produced a significant model (R² = 0.111, P = .006). The presence of ligamentous instability (β coefficient, -1.61) and the absence of mechanical symptoms (β coefficient, -0.67) were negative predictors of number of AUC interventions received. Variance inflation factors were 1.014 and 1.012, respectively. Likewise, regression modeling to identify factors predictive of receiving a rarely appropriate intervention also produced a significant model (pseudo R²= 0.06, P = .025), with lower Kellgren-Lawrence grade the only significant predictor of receiving a rarely appropriate intervention (odds ratio [OR] 0.54; 95% CI, 0.42 -0.72, per unit increase).

Timing from presentation to arthroplasty intervention was also evaluated. Age was a negative predictor (β coefficient -1.61), while positive predictors were reduced ROM (β coefficient 15.72) and having more AUC interventions (β coefficient 7.31) (model R²= 0.29, P = < .001). Age was the most significant predictor. Variance inflations factors were 1.02, 1.01, and 1.03, respectively. Receiving a rarely appropriate intervention was not associated with TKA timing.

Discussion

This single-center retrospective study examined the utilization of AAOS AUC-evaluated nonarthroplasty interventions for symptomatic knee OA prior to TKA. The aims of this study were to validate the AAOS AUC in a clinical setting and identify predictors of AAOS AUC utilization. In particular, this study focused on the number of interventions utilized prior to knee arthroplasty, whether interventions receiving a designation of rarely appropriate were used, and the duration of nonarthroplasty treatment.

Patients with knee instability used fewer total AAOS AUC evaluated interventions prior to TKA. Subjective instability has been reported as high as 27% in patients with OA and has been associated with fear of falling, poor balance confidence, activity limitations, and lower Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical function scores.¹² However, it has not been found to correlate with knee laxity.¹³ Nevertheless, significant functional impairment with the risk of falling may reduce the number of nonarthroplasty interventions attempted. On the other hand, the presence of mechanical symptoms resulted in greater utilization of nonarthroplasty interventions. This is likely due to the greater utilization of arthroscopic partial menisectomy or loose body removal in this group of patients. Despite its inclusion as an AAOS AUC evaluated intervention, arthroscopy remains a contentious treatment for symptomatic knee pain in the setting of OA.^14,15

For every unit decrease in Kellgren-Lawrence OA grade, patients were 54% more likely to receive a rarely appropriate intervention prior to knee arthroplasty. This is supported by the recent literature examining the AAOS AUC for surgical management of knee OA. Riddle and colleagues developed a classification tree to determine the contributions of various prognostic variables in final classifications of the 864 clinical vignettes used to develop the appropriateness algorithm and found that OA severity was strongly favored, with only 4 of the 432 vignettes with severe knee OA judged as rarely appropriate for surgical intervention.⁶

Our findings, too, may be explained by an AAOS AUC system that too heavily weighs radiographic severity of knee OA, resulting in more frequent rarely appropriate interventions in patients with less severe arthritis, including nonarthroplasty treatments. It is likely that rarely appropriate interventions were attempted in this subset of our study cohort based on patient’s subjective symptoms and functional status, both of which have been shown to be discordant with radiographic severity of knee OA.¹⁶

Oral or transcutaneous prescribed opioid medications were the most frequent intervention that received a rarely appropriate designation. Patients with preoperative opioid use undergoing TKA have been shown to have a greater risk for postoperative complications and longer hospital stay, particularly those patients aged < 75 years. Younger age, use of more interventions, and decreased knee ROM at presentation were predictive of longer duration of nonarthroplasty treatment. The use of more AAOS AUC evaluated interventions in these patients suggests that the AAOS AUC model may effectively be used to manage symptomatic OA, increasing the time from presentation to knee arthroplasty.

Interestingly, the use of rarely appropriate interventions did not affect TKA timing, as would be expected in a clinically effective nonarthroplasty treatment model. The reasons for rarely appropriate nonsurgical interventions are complex and require further investigation. One possible explanation is that decreased ROM was a marker for mechanical symptoms that necessitated additional intervention in the form of knee arthroscopy, delaying time to TKA.

Limitations

There are several limitations of this study. First, the small sample size (N = 90) requires acknowledgment; however, this limitation reflects the difficulty in following patients for years prior to an operative intervention. Second, the study population consists of veterans using the VA system and may not be reflective of the general population, differing with respect to gender, racial, and socioeconomic factors. Nevertheless, studies examining TKA utilization found, aside from racial and ethnic variability, patient gender and age do not affect arthroplasty utilization rate in the VA system.¹⁷

Additional limitations stem from the retrospective nature of this study. While the Computerized Patient Record System and centralized care of the VA system allows for review of all physical therapy consultations, orthotic consultations, and medications within the VA system, any treatments and intervention delivered by non-VA providers were not captured. Furthermore, the ability to assess for confounding variables limiting the prescription of certain medications, such as chronic kidney disease with NSAIDs or liver disease with acetaminophen, was limited by our study design.

Although our study suffers from selection bias with respect to examination of nonarthroplasty treatment in patients who have ultimately undergone TKA, we feel that this subset of patients with symptomatic knee OA represents the majority of patients evaluated for knee OA by orthopaedic surgeons in the clinic setting. It should be noted that although realignment osteotomies were sometimes indicated as appropriate by AAOS AUC model in our study population, this intervention was never performed due to patient and surgeon preference. Additionally, although it is not an AAOS AUC evaluated intervention, viscosupplementation was sporadically used during the study period; however, it is now off formulary at the investigation institution.

Conclusion

Our study suggests that patients without knee instability use more nonarthroplasty treatments over a longer period before TKA, and those patients with less severe knee OA are at risk of receiving an intervention judged to be rarely appropriate by the AAOS AUC. Such interventions do not affect timing of TKA. Nonarthroplasty care should be individualized to patients’ needs, and the decision to proceed with arthroplasty should be considered only after exhausting appropriate conservative measures. We recommend that providers use the AAOS AUC, especially when treating younger patients with less severe knee OA, particularly if considering opiate therapy or knee arthroscopy.

Acknowledgments
The authors would like to acknowledge Patrick Getty, MD, for his surgical care of some of the study patients. This material is the result of work supported with resources and the use of facilities at the Louis Stokes Cleveland VA Medical Center in Ohio.

Knee osteoarthritis (OA) affects almost 9.3 million adults in the US and accounts for $27 billion in annual health care expenses.^1,2 Due to the increasing cost of health care and an aging population, there has been renewed interest in establishing criteria for nonarthroplasty treatment of knee OA.

In 2013, using the RAND/UCLA Appropriateness method, the American Academy of Orthopaedic Surgeons (AAOS) developed an appropriate use criteria (AUC) for nonarthroplasty management of primary OA of the knee, based on orthopaedic literature and expert opinion.³ Interventions such as activity modification, weight loss, prescribed physical therapy, nonsteroidal anti-inflammatory drugs, tramadol, prescribed oral or transcutaneous opioids, acetaminophen, intra-articular corticosteroids, hinged or unloading knee braces, arthroscopic partial menisectomy or loose body removal, and realignment osteotomy were assessed. An algorithm was developed for 576 patients scenarios that incorporated patient-specific, prognostic/predictor variables to assign designations of “appropriate,” “may be appropriate,” or “rarely appropriate,” to treatment interventions.^4,5 An online version of the algorithm (orthoguidelines.org) is available for physicians and surgeons to judge appropriateness of nonarthroplasty treatments; however, it is not intended to mandate candidacy for treatment or intervention.

Clinical evaluation of the AAOS AUC is necessary to determine how treatment recommendations correlate with current practice. A recent examination of the AAOS Appropriateness System for Surgical Management of Knee OA found that prognostic/predictor variables, such as patient age, OA severity, and pattern of knee OA involvement were more heavily weighted when determining arthroplasty appropriateness than was pain severity or functional loss.⁶ Furthermore, non-AAOS AUC prognostic/predictor variables, such as race and gender, have been linked to disparities in utilization of knee OA interventions.^7-9 Such disparities can be costly not just from a patient perceptive, but also employer and societal perspectives.¹⁰

The Department of Veterans Affairs (VA) health care system represents a model of equal-access-to care system in the US that is ideal for examination of issues about health care utilization and any disparities within the AAOS AUC model and has previously been used to assess utilization of total knee arthroplasty.⁹ The aim of this study was to characterize utilization of the AAOS AUC for nonarthroplasty treatment of knee OA in a VA patient population. We asked the following questions: (1) What variables are predictive of receiving a greater number of AAOS AUC evaluated nonarthroplasty treatments? (2) What variables are predictive of receiving “rarely appropriate” AAOS AUC evaluated nonarthroplasty treatment? (3) What factors are predictive of duration of nonarthroplasty care until total knee arthroplasty (TKA)?

Methods

The institutional review board at the Louis Stokes Cleveland VA Medical Center in Ohio approved a retrospective chart review of nonarthroplasty treatments utilized by patients presenting to its orthopaedic section who subsequently underwent knee arthroplasty between 2013 and 2016. Eligibility criteria included patients aged ≥ 30 years with a diagnosis of unilateral or bilateral primary knee OA. Patients with posttraumatic OA, inflammatory arthritis, and a history of infectious arthritis or Charcot arthropathy of the knee were excluded. Patients with a body mass index (BMI) > 40 or a hemoglobin A_1c > 8.0 at presentation were excluded as nonarthroplasty care was the recommended course of treatment above these thresholds.

Data collected included race, gender, duration of nonarthroplasty treatment, BMI, and Kellgren-Lawrence classification of knee OA at time of presentation for symptomatic knee OA.¹¹ All AAOS AUC-evaluated nonarthroplasty treatments utilized prior to arthroplasty intervention also were recorded (Table 1). 

Statistical Analysis

Statistical analysis was completed with GraphPad Software Prism 7.0a (La Jolla, CA) and Mathworks MatLab R2016b software (Natick, MA). Univariate analysis with Student t tests with Welch corrections in the setting of unequal variance, Mann-Whitney nonparametric tests, and Fisher exact test were generated in the appropriate setting. Multivariable analyses also were conducted. For continuous outcomes, stepwise multiple linear regression was used to generate predictive models; for binary outcomes, binomial logistic regression was used.

Factors analyzed in regression modeling for the total number of AAOS AUC evaluated nonarthroplasty treatments utilized and the likelihood of receiving a rarely appropriate treatment included gender, race, function-limiting pain, range of motion (ROM), ligamentous instability, arthritis pattern, limb alignment, mechanical symptoms, BMI, age, and Kellgren-Lawrence grade. Factors analyzed in timing of TKA included the above variables plus the total number of AUC interventions, whether the patient received an inappropriate intervention, and average appropriateness of the interventions received. Residual analysis with Cook’s distance was used to identify outliers in regression. Observations with Cook’s distance > 3 times the mean Cook’s distance were identified as potential outliers, and models were adjusted accordingly. All statistical analyses were 2-tailed. Statistical significance was set to P ≤ .05 for all outputs.

Results

In the study, 97.8% of participants identified as male, and the mean age was 62.8 years (Table 3). 

Appropriate Use Criteria Interventions

Patients received a mean of 5.2 AAOS AUC evaluated interventions before undergoing arthroplasty management at a mean of 32.3 months (range 2-181 months) from initial presentation. The majority of these interventions were classified as either appropriate or may be appropriate, according to the AUC definitions (95.1%). Self-management and physical therapy programs were widely utilized (100% and 90.1%, respectively), with all use of these interventions classified as appropriate.

Hinged or unloader knee braces were utilized in about half the study patients; this intervention was classified as rarely appropriate in 4.4% of these patients. Medical therapy was also widely used, with all use of NSAIDs, acetaminophen, and tramadol classified as appropriate or may be appropriate. Oral or transcutaneous opioid medications were prescribed in 14.3% of patients, with 92.3% of this use classified as rarely appropriate. Although the opioid medication prescribing provider was not specifically evaluated, there were no instances in which the orthopaedic service provided an oral or transcutaneous opioid prescriptions. Procedural interventions, with the exception of corticosteroid injections, were uncommon; no patient received realignment osteotomy, and only 12.1% of patients underwent arthroscopy. The use of arthroscopy was deemed rarely appropriate in 72.7% of these cases.

Factors Associated With AAOS AUC Intervention Use

There was no difference in the number of AAOS AUC evaluated interventions received based on BMI (mean [SD] BMI < 35, 5.2 [1.0] vs BMI ≥ 35, 5.3 [1.1], P = .49), age (mean [SD] aged < 60 years, 5.4 [1.0] vs aged ≥ 60 years, 5.1 [1.2], P = .23), or Kellgren-Lawrence arthritic grade (mean [SD] grade ≤ 2, 5.5 [1.0] vs grade > 2, 5.1 [1.1], P = .06). These variables also were not associated with receiving a rarely appropriate intervention (mean [SD] BMI < 35, 0.27 [0.5] vs BMI > 35, 0.2 [0.4], P = .81; aged > 60 years, 0.3 [0.5] vs aged < 60 years, 0.2 [0.4], P = .26; Kellgren-Lawrence grade < 2, 0.4 [0.6] vs grade > 2, 0.2 [0.4], P = .1).

Regression modeling to predict total number of AAOS AUC evaluated interventions received produced a significant model (R² = 0.111, P = .006). The presence of ligamentous instability (β coefficient, -1.61) and the absence of mechanical symptoms (β coefficient, -0.67) were negative predictors of number of AUC interventions received. Variance inflation factors were 1.014 and 1.012, respectively. Likewise, regression modeling to identify factors predictive of receiving a rarely appropriate intervention also produced a significant model (pseudo R²= 0.06, P = .025), with lower Kellgren-Lawrence grade the only significant predictor of receiving a rarely appropriate intervention (odds ratio [OR] 0.54; 95% CI, 0.42 -0.72, per unit increase).

Timing from presentation to arthroplasty intervention was also evaluated. Age was a negative predictor (β coefficient -1.61), while positive predictors were reduced ROM (β coefficient 15.72) and having more AUC interventions (β coefficient 7.31) (model R²= 0.29, P = < .001). Age was the most significant predictor. Variance inflations factors were 1.02, 1.01, and 1.03, respectively. Receiving a rarely appropriate intervention was not associated with TKA timing.

Discussion

This single-center retrospective study examined the utilization of AAOS AUC-evaluated nonarthroplasty interventions for symptomatic knee OA prior to TKA. The aims of this study were to validate the AAOS AUC in a clinical setting and identify predictors of AAOS AUC utilization. In particular, this study focused on the number of interventions utilized prior to knee arthroplasty, whether interventions receiving a designation of rarely appropriate were used, and the duration of nonarthroplasty treatment.

Patients with knee instability used fewer total AAOS AUC evaluated interventions prior to TKA. Subjective instability has been reported as high as 27% in patients with OA and has been associated with fear of falling, poor balance confidence, activity limitations, and lower Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical function scores.¹² However, it has not been found to correlate with knee laxity.¹³ Nevertheless, significant functional impairment with the risk of falling may reduce the number of nonarthroplasty interventions attempted. On the other hand, the presence of mechanical symptoms resulted in greater utilization of nonarthroplasty interventions. This is likely due to the greater utilization of arthroscopic partial menisectomy or loose body removal in this group of patients. Despite its inclusion as an AAOS AUC evaluated intervention, arthroscopy remains a contentious treatment for symptomatic knee pain in the setting of OA.^14,15

For every unit decrease in Kellgren-Lawrence OA grade, patients were 54% more likely to receive a rarely appropriate intervention prior to knee arthroplasty. This is supported by the recent literature examining the AAOS AUC for surgical management of knee OA. Riddle and colleagues developed a classification tree to determine the contributions of various prognostic variables in final classifications of the 864 clinical vignettes used to develop the appropriateness algorithm and found that OA severity was strongly favored, with only 4 of the 432 vignettes with severe knee OA judged as rarely appropriate for surgical intervention.⁶

Our findings, too, may be explained by an AAOS AUC system that too heavily weighs radiographic severity of knee OA, resulting in more frequent rarely appropriate interventions in patients with less severe arthritis, including nonarthroplasty treatments. It is likely that rarely appropriate interventions were attempted in this subset of our study cohort based on patient’s subjective symptoms and functional status, both of which have been shown to be discordant with radiographic severity of knee OA.¹⁶

Oral or transcutaneous prescribed opioid medications were the most frequent intervention that received a rarely appropriate designation. Patients with preoperative opioid use undergoing TKA have been shown to have a greater risk for postoperative complications and longer hospital stay, particularly those patients aged < 75 years. Younger age, use of more interventions, and decreased knee ROM at presentation were predictive of longer duration of nonarthroplasty treatment. The use of more AAOS AUC evaluated interventions in these patients suggests that the AAOS AUC model may effectively be used to manage symptomatic OA, increasing the time from presentation to knee arthroplasty.

Interestingly, the use of rarely appropriate interventions did not affect TKA timing, as would be expected in a clinically effective nonarthroplasty treatment model. The reasons for rarely appropriate nonsurgical interventions are complex and require further investigation. One possible explanation is that decreased ROM was a marker for mechanical symptoms that necessitated additional intervention in the form of knee arthroscopy, delaying time to TKA.

Limitations

There are several limitations of this study. First, the small sample size (N = 90) requires acknowledgment; however, this limitation reflects the difficulty in following patients for years prior to an operative intervention. Second, the study population consists of veterans using the VA system and may not be reflective of the general population, differing with respect to gender, racial, and socioeconomic factors. Nevertheless, studies examining TKA utilization found, aside from racial and ethnic variability, patient gender and age do not affect arthroplasty utilization rate in the VA system.¹⁷

Additional limitations stem from the retrospective nature of this study. While the Computerized Patient Record System and centralized care of the VA system allows for review of all physical therapy consultations, orthotic consultations, and medications within the VA system, any treatments and intervention delivered by non-VA providers were not captured. Furthermore, the ability to assess for confounding variables limiting the prescription of certain medications, such as chronic kidney disease with NSAIDs or liver disease with acetaminophen, was limited by our study design.

Although our study suffers from selection bias with respect to examination of nonarthroplasty treatment in patients who have ultimately undergone TKA, we feel that this subset of patients with symptomatic knee OA represents the majority of patients evaluated for knee OA by orthopaedic surgeons in the clinic setting. It should be noted that although realignment osteotomies were sometimes indicated as appropriate by AAOS AUC model in our study population, this intervention was never performed due to patient and surgeon preference. Additionally, although it is not an AAOS AUC evaluated intervention, viscosupplementation was sporadically used during the study period; however, it is now off formulary at the investigation institution.

Conclusion

Our study suggests that patients without knee instability use more nonarthroplasty treatments over a longer period before TKA, and those patients with less severe knee OA are at risk of receiving an intervention judged to be rarely appropriate by the AAOS AUC. Such interventions do not affect timing of TKA. Nonarthroplasty care should be individualized to patients’ needs, and the decision to proceed with arthroplasty should be considered only after exhausting appropriate conservative measures. We recommend that providers use the AAOS AUC, especially when treating younger patients with less severe knee OA, particularly if considering opiate therapy or knee arthroscopy.

Acknowledgments
The authors would like to acknowledge Patrick Getty, MD, for his surgical care of some of the study patients. This material is the result of work supported with resources and the use of facilities at the Louis Stokes Cleveland VA Medical Center in Ohio.

EVIDENCE SUMMARY

PRP vs placebo. Three RCTs compared PRP with saline placebo injections and 2 found that PRP improved the Western Ontario and McMaster Universities Arthritis Index (WOMAC, a standardized scale assessing knee pain, function, and stiffness) by 40% to 70%; the third found 24% to 32% improvements in the EuroQol visual analog scale (EQ-VAS) scores at 6 months^1-3 (TABLE^1-12).

The first 2 studies enrolled patients (mean age early 60s, approximately 50% women) with clinically and radiographically evaluated knee OA of mostly moderate severity (baseline WOMAC scores about 50).^1,2 Investigators in the first RCT injected PRP once in one subgroup and twice in another subgroup, compared with a single injection of saline in a third subgroup.¹ They gave 3 weekly injections of PRP or saline in the second RCT.²

The third study enrolled mainly patients with early osteoarthritis (mean age early 50s, slightly more women). Investigators injected PRP 3 times in one subgroup and once (plus 2 saline injections) in another, compared with 3 saline injections, and evaluated patients at baseline and 6 months.³

PRP vs HA. Nine RCTs compared PRP with HA injections. Six studies (673 patients) found no significant difference; 3 studies (376 patients) found that PRP improved standardized knee assessment scores by 35% to 40% at 24-48 weeks.^7,8,10 All studies enrolled patients (mean age early 60s, approximately 50% women) with clinically and radiographically evaluated knee OA of mostly moderate severity. In 7 RCTs, ^4-6,9-12 investigators injected PRP or HA weekly for 3 weeks, in one RCT⁸ they gave 4 weekly injections, and in one⁷they gave 2 PRP injections separated by 4 weeks.

Three RCTs used the International Knee Documentation Committee (IKDC) score, considered the most reliable standardized scoring system, which quantifies subjective symptoms (pain, stiffness, swelling, giving way), activity (climbing stairs, rising from a chair, squatting, jumping), and function pre- and postintervention.^5,9,12 All 3 studies using the IKDC found no difference between PRP and HA injections. Most RCTs used the WOMAC standardized scale, scoring 5 items for pain, 2 for stiffness, and 17 for function.^1,2,4,6-8.10

Risk for bias

A systematic review¹³ that evaluated methodologic quality of the 3 studies comparing PRP with placebo rated 2^1,3 at high risk of bias and one² at moderate risk. Another meta-analysis¹⁴ performed a quality assessment including 4 of the 9 RCTs^,8-10,12 comparing PRP with HA and concluded that 3 had a high risk of bias; the fourth RCT had a moderate risk. No independent quality assessments of the other RCTs were available.^4-7,11

RECOMMENDATIONS

The American Academy of Orthopaedic Surgeons doesn’t recommend for or against PRP injections because of insufficient evidence and strongly recommends against HA injections based on multiple RCTs of moderate quality that found no difference between HA and placebo.¹⁵

EVIDENCE SUMMARY

PRP vs placebo. Three RCTs compared PRP with saline placebo injections and 2 found that PRP improved the Western Ontario and McMaster Universities Arthritis Index (WOMAC, a standardized scale assessing knee pain, function, and stiffness) by 40% to 70%; the third found 24% to 32% improvements in the EuroQol visual analog scale (EQ-VAS) scores at 6 months^1-3 (TABLE^1-12).

The first 2 studies enrolled patients (mean age early 60s, approximately 50% women) with clinically and radiographically evaluated knee OA of mostly moderate severity (baseline WOMAC scores about 50).^1,2 Investigators in the first RCT injected PRP once in one subgroup and twice in another subgroup, compared with a single injection of saline in a third subgroup.¹ They gave 3 weekly injections of PRP or saline in the second RCT.²

The third study enrolled mainly patients with early osteoarthritis (mean age early 50s, slightly more women). Investigators injected PRP 3 times in one subgroup and once (plus 2 saline injections) in another, compared with 3 saline injections, and evaluated patients at baseline and 6 months.³

PRP vs HA. Nine RCTs compared PRP with HA injections. Six studies (673 patients) found no significant difference; 3 studies (376 patients) found that PRP improved standardized knee assessment scores by 35% to 40% at 24-48 weeks.^7,8,10 All studies enrolled patients (mean age early 60s, approximately 50% women) with clinically and radiographically evaluated knee OA of mostly moderate severity. In 7 RCTs, ^4-6,9-12 investigators injected PRP or HA weekly for 3 weeks, in one RCT⁸ they gave 4 weekly injections, and in one⁷they gave 2 PRP injections separated by 4 weeks.

Three RCTs used the International Knee Documentation Committee (IKDC) score, considered the most reliable standardized scoring system, which quantifies subjective symptoms (pain, stiffness, swelling, giving way), activity (climbing stairs, rising from a chair, squatting, jumping), and function pre- and postintervention.^5,9,12 All 3 studies using the IKDC found no difference between PRP and HA injections. Most RCTs used the WOMAC standardized scale, scoring 5 items for pain, 2 for stiffness, and 17 for function.^1,2,4,6-8.10

Risk for bias

A systematic review¹³ that evaluated methodologic quality of the 3 studies comparing PRP with placebo rated 2^1,3 at high risk of bias and one² at moderate risk. Another meta-analysis¹⁴ performed a quality assessment including 4 of the 9 RCTs^,8-10,12 comparing PRP with HA and concluded that 3 had a high risk of bias; the fourth RCT had a moderate risk. No independent quality assessments of the other RCTs were available.^4-7,11

RECOMMENDATIONS

The American Academy of Orthopaedic Surgeons doesn’t recommend for or against PRP injections because of insufficient evidence and strongly recommends against HA injections based on multiple RCTs of moderate quality that found no difference between HA and placebo.¹⁵

EVIDENCE SUMMARY

PRP vs placebo. Three RCTs compared PRP with saline placebo injections and 2 found that PRP improved the Western Ontario and McMaster Universities Arthritis Index (WOMAC, a standardized scale assessing knee pain, function, and stiffness) by 40% to 70%; the third found 24% to 32% improvements in the EuroQol visual analog scale (EQ-VAS) scores at 6 months^1-3 (TABLE^1-12).

The first 2 studies enrolled patients (mean age early 60s, approximately 50% women) with clinically and radiographically evaluated knee OA of mostly moderate severity (baseline WOMAC scores about 50).^1,2 Investigators in the first RCT injected PRP once in one subgroup and twice in another subgroup, compared with a single injection of saline in a third subgroup.¹ They gave 3 weekly injections of PRP or saline in the second RCT.²

The third study enrolled mainly patients with early osteoarthritis (mean age early 50s, slightly more women). Investigators injected PRP 3 times in one subgroup and once (plus 2 saline injections) in another, compared with 3 saline injections, and evaluated patients at baseline and 6 months.³

PRP vs HA. Nine RCTs compared PRP with HA injections. Six studies (673 patients) found no significant difference; 3 studies (376 patients) found that PRP improved standardized knee assessment scores by 35% to 40% at 24-48 weeks.^7,8,10 All studies enrolled patients (mean age early 60s, approximately 50% women) with clinically and radiographically evaluated knee OA of mostly moderate severity. In 7 RCTs, ^4-6,9-12 investigators injected PRP or HA weekly for 3 weeks, in one RCT⁸ they gave 4 weekly injections, and in one⁷they gave 2 PRP injections separated by 4 weeks.

Three RCTs used the International Knee Documentation Committee (IKDC) score, considered the most reliable standardized scoring system, which quantifies subjective symptoms (pain, stiffness, swelling, giving way), activity (climbing stairs, rising from a chair, squatting, jumping), and function pre- and postintervention.^5,9,12 All 3 studies using the IKDC found no difference between PRP and HA injections. Most RCTs used the WOMAC standardized scale, scoring 5 items for pain, 2 for stiffness, and 17 for function.^1,2,4,6-8.10

Risk for bias

A systematic review¹³ that evaluated methodologic quality of the 3 studies comparing PRP with placebo rated 2^1,3 at high risk of bias and one² at moderate risk. Another meta-analysis¹⁴ performed a quality assessment including 4 of the 9 RCTs^,8-10,12 comparing PRP with HA and concluded that 3 had a high risk of bias; the fourth RCT had a moderate risk. No independent quality assessments of the other RCTs were available.^4-7,11

RECOMMENDATIONS

The American Academy of Orthopaedic Surgeons doesn’t recommend for or against PRP injections because of insufficient evidence and strongly recommends against HA injections based on multiple RCTs of moderate quality that found no difference between HA and placebo.¹⁵

WASHINGTON – An investigational molecule that blocks the downstream proinflammatory effects of B cells controlled disease activity and induced clinical remission in patients with pemphigus by 12 weeks.

At the end of a 24-week, open-label trial, patients taking the oral inhibitor of Bruton tyrosine kinase (BTK) plus very-low-dose prednisone also experienced a mean 65% reduction in antidesmoglein antibodies, a key driver of the sometimes-fatal blistering disease, Deedee Murrell, MD, said at the annual meeting of the American Academy of Dermatology.

The clinical efficacy plus a favorable safety profile supports the further development of the molecule, designed and manufactured by Principia Biopharma in San Francisco. The company is currently recruiting for a pivotal phase 3 trial of PRN1008 in 120 patients with moderate to severe pemphigus vulgaris.

Despite the recent approval of rituximab (Rituxan) for moderate to severe pemphigus, there remains an unmet need for a quick-acting, steroid-sparing, anti-inflammatory treatment, said Dr. Murrell, professor and head of the department of dermatology at the University of New South Wales, Sydney.

“We need something to use instead of high-dose steroids while we are waiting for rituximab to kick in, which can take 3 months,” and rituximab, which depletes B cells, puts patients at risk for infection, she said. “We need something that has rapid onset, is steroid sparing, safe for chronic administration, avoids B-cell depletion, and is convenient.”

Blocking the BTK receptor on B cells puts the brakes on the B-cell mediated inflammatory pathway, preventing activation of monocytes, macrophages, mast cells, basophils, and neutrophils. At the same time, however, it does not deplete the B-cell population, said Dr. Murrell, the lead investigator.

The BELIEVE study comprised 27 patients with mild to severe pemphigus of an average 6 years’ duration. Most (18) had relapsing disease; the remainder had newly diagnosed pemphigus. A majority (16) had severe disease, as measured by a score of 15 or more on the Pemphigus Disease Activity Index (PDAI). Almost all (23) were positive for antidesmoglein antibodies. Only one patient was negative for antibodies.

The mean corticosteroid dose at baseline was 14 mg/day, although that ranged from no steroids to 30 mg/day.

The study consisted of a 12-week treatment phase and a 12-week follow-up phase. During treatment, patients could take no more than 0.5 mg/kg of prednisone daily, although with 400 mg PRN1008 twice a day. They were allowed to undertake rescue immunosuppression if they experienced a disease flare.

The primary endpoint was disease control by day 29 as evidenced by no new lesions. Secondary endpoints were complete remission, minimization of prednisone, quality of life, antibody levels, and clinician measures including the PDAI and the Autoimmune Bullous Skin Disorder Intensity Score.

By the end of week 4, 54% of patients had achieved the primary endpoint. The benefit continued to expand, with 73% reaching that response by the end of week 12. During this period, the mean prednisone dose was 12 mg/day.

Among the 24 patients who completed the study, complete remission occurred in 17% by week 12. However, patients continued to respond through the follow-up period, even after the study medication was stopped. By week 24, 25% of these patients experienced a complete remission. At the point of remission, the mean steroid dose was 8 mg/day. The median duration of remission was 2 months after stopping PRN1008.

The PDAI fell by a median of 70% by week 12 and was maintained at that level by the end of week 24. The median level of antidesmoglein autoantibodies fell by up to 65%. Again, the improvement continued throughout the off-drug follow-up period. In subgroup analyses, PRN1008 was more effective in patients with moderate to severe disease than those with mild disease (80% response vs. 64%). It was equally effective in those with newly diagnosed disease (75% vs. 72%) and regardless of antibody level at baseline.

The adverse event profile was relatively benign. Most side effects were mild and transient, and included upper abdominal pain, headache, and nausea. There were two mild infections and one serious infection, which presented in a patient with a long-standing localized cellulitis that activated and was associated a high fever. It was culture negative and PRN1008 was restarted without issue.

There was also one serious adverse event and one death, both unrelated to the study drug. One patient developed a pancreatic cyst that was discovered on day 29. The patient dropped out of the study to have elective surgery. The death occurred in a patient who developed acute respiratory failure on day 8 of treatment, caused by an undiagnosed congenital pulmonary sequestration. The patient died of a brain embolism shortly after lung surgery.

Dr. Murrell designed the study and was an investigator. She reported a financial relationship with Principia, as well as with numerous other pharmaceutical companies.

msullivan@mdege.com

SOURCE: Murrell D et al. AAD 2019, Session S034.

WASHINGTON – An investigational molecule that blocks the downstream proinflammatory effects of B cells controlled disease activity and induced clinical remission in patients with pemphigus by 12 weeks.

At the end of a 24-week, open-label trial, patients taking the oral inhibitor of Bruton tyrosine kinase (BTK) plus very-low-dose prednisone also experienced a mean 65% reduction in antidesmoglein antibodies, a key driver of the sometimes-fatal blistering disease, Deedee Murrell, MD, said at the annual meeting of the American Academy of Dermatology.

The clinical efficacy plus a favorable safety profile supports the further development of the molecule, designed and manufactured by Principia Biopharma in San Francisco. The company is currently recruiting for a pivotal phase 3 trial of PRN1008 in 120 patients with moderate to severe pemphigus vulgaris.

Despite the recent approval of rituximab (Rituxan) for moderate to severe pemphigus, there remains an unmet need for a quick-acting, steroid-sparing, anti-inflammatory treatment, said Dr. Murrell, professor and head of the department of dermatology at the University of New South Wales, Sydney.

“We need something to use instead of high-dose steroids while we are waiting for rituximab to kick in, which can take 3 months,” and rituximab, which depletes B cells, puts patients at risk for infection, she said. “We need something that has rapid onset, is steroid sparing, safe for chronic administration, avoids B-cell depletion, and is convenient.”

Blocking the BTK receptor on B cells puts the brakes on the B-cell mediated inflammatory pathway, preventing activation of monocytes, macrophages, mast cells, basophils, and neutrophils. At the same time, however, it does not deplete the B-cell population, said Dr. Murrell, the lead investigator.

The BELIEVE study comprised 27 patients with mild to severe pemphigus of an average 6 years’ duration. Most (18) had relapsing disease; the remainder had newly diagnosed pemphigus. A majority (16) had severe disease, as measured by a score of 15 or more on the Pemphigus Disease Activity Index (PDAI). Almost all (23) were positive for antidesmoglein antibodies. Only one patient was negative for antibodies.

The mean corticosteroid dose at baseline was 14 mg/day, although that ranged from no steroids to 30 mg/day.

The study consisted of a 12-week treatment phase and a 12-week follow-up phase. During treatment, patients could take no more than 0.5 mg/kg of prednisone daily, although with 400 mg PRN1008 twice a day. They were allowed to undertake rescue immunosuppression if they experienced a disease flare.

The primary endpoint was disease control by day 29 as evidenced by no new lesions. Secondary endpoints were complete remission, minimization of prednisone, quality of life, antibody levels, and clinician measures including the PDAI and the Autoimmune Bullous Skin Disorder Intensity Score.

By the end of week 4, 54% of patients had achieved the primary endpoint. The benefit continued to expand, with 73% reaching that response by the end of week 12. During this period, the mean prednisone dose was 12 mg/day.

Among the 24 patients who completed the study, complete remission occurred in 17% by week 12. However, patients continued to respond through the follow-up period, even after the study medication was stopped. By week 24, 25% of these patients experienced a complete remission. At the point of remission, the mean steroid dose was 8 mg/day. The median duration of remission was 2 months after stopping PRN1008.

The PDAI fell by a median of 70% by week 12 and was maintained at that level by the end of week 24. The median level of antidesmoglein autoantibodies fell by up to 65%. Again, the improvement continued throughout the off-drug follow-up period. In subgroup analyses, PRN1008 was more effective in patients with moderate to severe disease than those with mild disease (80% response vs. 64%). It was equally effective in those with newly diagnosed disease (75% vs. 72%) and regardless of antibody level at baseline.

The adverse event profile was relatively benign. Most side effects were mild and transient, and included upper abdominal pain, headache, and nausea. There were two mild infections and one serious infection, which presented in a patient with a long-standing localized cellulitis that activated and was associated a high fever. It was culture negative and PRN1008 was restarted without issue.

There was also one serious adverse event and one death, both unrelated to the study drug. One patient developed a pancreatic cyst that was discovered on day 29. The patient dropped out of the study to have elective surgery. The death occurred in a patient who developed acute respiratory failure on day 8 of treatment, caused by an undiagnosed congenital pulmonary sequestration. The patient died of a brain embolism shortly after lung surgery.

Dr. Murrell designed the study and was an investigator. She reported a financial relationship with Principia, as well as with numerous other pharmaceutical companies.

msullivan@mdege.com

SOURCE: Murrell D et al. AAD 2019, Session S034.

WASHINGTON – An investigational molecule that blocks the downstream proinflammatory effects of B cells controlled disease activity and induced clinical remission in patients with pemphigus by 12 weeks.

At the end of a 24-week, open-label trial, patients taking the oral inhibitor of Bruton tyrosine kinase (BTK) plus very-low-dose prednisone also experienced a mean 65% reduction in antidesmoglein antibodies, a key driver of the sometimes-fatal blistering disease, Deedee Murrell, MD, said at the annual meeting of the American Academy of Dermatology.

The clinical efficacy plus a favorable safety profile supports the further development of the molecule, designed and manufactured by Principia Biopharma in San Francisco. The company is currently recruiting for a pivotal phase 3 trial of PRN1008 in 120 patients with moderate to severe pemphigus vulgaris.

Despite the recent approval of rituximab (Rituxan) for moderate to severe pemphigus, there remains an unmet need for a quick-acting, steroid-sparing, anti-inflammatory treatment, said Dr. Murrell, professor and head of the department of dermatology at the University of New South Wales, Sydney.

“We need something to use instead of high-dose steroids while we are waiting for rituximab to kick in, which can take 3 months,” and rituximab, which depletes B cells, puts patients at risk for infection, she said. “We need something that has rapid onset, is steroid sparing, safe for chronic administration, avoids B-cell depletion, and is convenient.”

Blocking the BTK receptor on B cells puts the brakes on the B-cell mediated inflammatory pathway, preventing activation of monocytes, macrophages, mast cells, basophils, and neutrophils. At the same time, however, it does not deplete the B-cell population, said Dr. Murrell, the lead investigator.

The BELIEVE study comprised 27 patients with mild to severe pemphigus of an average 6 years’ duration. Most (18) had relapsing disease; the remainder had newly diagnosed pemphigus. A majority (16) had severe disease, as measured by a score of 15 or more on the Pemphigus Disease Activity Index (PDAI). Almost all (23) were positive for antidesmoglein antibodies. Only one patient was negative for antibodies.

The mean corticosteroid dose at baseline was 14 mg/day, although that ranged from no steroids to 30 mg/day.

The study consisted of a 12-week treatment phase and a 12-week follow-up phase. During treatment, patients could take no more than 0.5 mg/kg of prednisone daily, although with 400 mg PRN1008 twice a day. They were allowed to undertake rescue immunosuppression if they experienced a disease flare.

The primary endpoint was disease control by day 29 as evidenced by no new lesions. Secondary endpoints were complete remission, minimization of prednisone, quality of life, antibody levels, and clinician measures including the PDAI and the Autoimmune Bullous Skin Disorder Intensity Score.

By the end of week 4, 54% of patients had achieved the primary endpoint. The benefit continued to expand, with 73% reaching that response by the end of week 12. During this period, the mean prednisone dose was 12 mg/day.

Among the 24 patients who completed the study, complete remission occurred in 17% by week 12. However, patients continued to respond through the follow-up period, even after the study medication was stopped. By week 24, 25% of these patients experienced a complete remission. At the point of remission, the mean steroid dose was 8 mg/day. The median duration of remission was 2 months after stopping PRN1008.

The PDAI fell by a median of 70% by week 12 and was maintained at that level by the end of week 24. The median level of antidesmoglein autoantibodies fell by up to 65%. Again, the improvement continued throughout the off-drug follow-up period. In subgroup analyses, PRN1008 was more effective in patients with moderate to severe disease than those with mild disease (80% response vs. 64%). It was equally effective in those with newly diagnosed disease (75% vs. 72%) and regardless of antibody level at baseline.

The adverse event profile was relatively benign. Most side effects were mild and transient, and included upper abdominal pain, headache, and nausea. There were two mild infections and one serious infection, which presented in a patient with a long-standing localized cellulitis that activated and was associated a high fever. It was culture negative and PRN1008 was restarted without issue.

There was also one serious adverse event and one death, both unrelated to the study drug. One patient developed a pancreatic cyst that was discovered on day 29. The patient dropped out of the study to have elective surgery. The death occurred in a patient who developed acute respiratory failure on day 8 of treatment, caused by an undiagnosed congenital pulmonary sequestration. The patient died of a brain embolism shortly after lung surgery.

Dr. Murrell designed the study and was an investigator. She reported a financial relationship with Principia, as well as with numerous other pharmaceutical companies.

msullivan@mdege.com

SOURCE: Murrell D et al. AAD 2019, Session S034.

For patients with early psoriatic arthritis, starting the tumor necrosis factor inhibitor golimumab (Simponi) at the same time as methotrexate nearly doubled the chances of remission, compared with methotrexate monotherapy, researchers reported in Annals of the Rheumatic Diseases.

In this multicenter, double-blind trial, 51 adults with CASPAR-defined psoriatic arthritis who were naive to methotrexate and biologic disease-modifying antirheumatic drugs were randomly assigned to receive monthly golimumab (50 mg subcutaneously) or placebo, in addition to methotrexate (15 mg/week, increased to 25 mg/week over 8 weeks). All patients had current active disease: At baseline, most had at least five swollen joints and at least nine tender joints.

Among 45 patients who completed the study, rates of Disease Activity Score (DAS) remission (DAS C-reactive protein score less than 1.6) at week 22 were 81% for golimumab-methotrexate and 42% for methotrexate-placebo (P = .004). “This difference in DAS remission was already observed at week 8,” wrote Leonieke J.J. van Mens, MD, of AMC/University of Amsterdam and her colleagues.

Golimumab-methotrexate also topped methotrexate monotherapy on secondary outcome measures. By week 22, median swollen joint counts were 0 with combined therapy versus 3 with methotrexate monotherapy (P = .04). Median tender joint counts were 0 and 2, respectively (P = .02). Combined golimumab-methotrexate therapy also produced significantly higher rates of low disease activity based on Disease Activity in Psoriatic Arthritis score (92% vs. 54%, respectively), Minimal Disease Activity (81% vs. 29%), and ACR20, 50, or 70 response (85% vs. 58%, 81% vs. 33%, and 58% vs. 13%, respectively).


Most differences were already statistically significant by week 8, and many were more pronounced by week 22, the researchers said. “It remains unknown if the responses – in particular the stringent responses such as remission – have already plateaued at week 22 or could even further increase over time,” they added. “Similarly, it remains to be determined if the combination of tumor necrosis factor inhibitor and methotrexate is only needed for the induction of remission or is also needed to maintain this state of remission over time.”

They explained that golimumab (or placebo) was stopped at week 22 in patients who achieved DAS CRP remission. An extension of the current study will assess whether methotrexate monotherapy can maintain responses for up to 50 weeks.

The only serious adverse event in the study occurred in the methotrexate arm and consisted of spinal stenosis that was not seen as treatment related. Rates of other adverse events were similar between arms, and those that required a dose halt or dose reduction were related to methotrexate, not golimumab. There were no deaths on trial.

Merck Sharp & Dohme provided medication and unrestricted funding for the study. Dr. van Mens and two coinvestigators reported having no disclosures. Several other coinvestigators disclosed ties to UCB, AbbVie, Novartis, Janssen, Eli Lilly, and other pharmaceutical companies.

SOURCE: van Mens LJJ et al. Ann Rheum Dis. 2019 Feb 26. doi: 10.1136/annrheumdis-2018-214746.

For patients with early psoriatic arthritis, starting the tumor necrosis factor inhibitor golimumab (Simponi) at the same time as methotrexate nearly doubled the chances of remission, compared with methotrexate monotherapy, researchers reported in Annals of the Rheumatic Diseases.

In this multicenter, double-blind trial, 51 adults with CASPAR-defined psoriatic arthritis who were naive to methotrexate and biologic disease-modifying antirheumatic drugs were randomly assigned to receive monthly golimumab (50 mg subcutaneously) or placebo, in addition to methotrexate (15 mg/week, increased to 25 mg/week over 8 weeks). All patients had current active disease: At baseline, most had at least five swollen joints and at least nine tender joints.

Among 45 patients who completed the study, rates of Disease Activity Score (DAS) remission (DAS C-reactive protein score less than 1.6) at week 22 were 81% for golimumab-methotrexate and 42% for methotrexate-placebo (P = .004). “This difference in DAS remission was already observed at week 8,” wrote Leonieke J.J. van Mens, MD, of AMC/University of Amsterdam and her colleagues.

Golimumab-methotrexate also topped methotrexate monotherapy on secondary outcome measures. By week 22, median swollen joint counts were 0 with combined therapy versus 3 with methotrexate monotherapy (P = .04). Median tender joint counts were 0 and 2, respectively (P = .02). Combined golimumab-methotrexate therapy also produced significantly higher rates of low disease activity based on Disease Activity in Psoriatic Arthritis score (92% vs. 54%, respectively), Minimal Disease Activity (81% vs. 29%), and ACR20, 50, or 70 response (85% vs. 58%, 81% vs. 33%, and 58% vs. 13%, respectively).


Most differences were already statistically significant by week 8, and many were more pronounced by week 22, the researchers said. “It remains unknown if the responses – in particular the stringent responses such as remission – have already plateaued at week 22 or could even further increase over time,” they added. “Similarly, it remains to be determined if the combination of tumor necrosis factor inhibitor and methotrexate is only needed for the induction of remission or is also needed to maintain this state of remission over time.”

They explained that golimumab (or placebo) was stopped at week 22 in patients who achieved DAS CRP remission. An extension of the current study will assess whether methotrexate monotherapy can maintain responses for up to 50 weeks.

The only serious adverse event in the study occurred in the methotrexate arm and consisted of spinal stenosis that was not seen as treatment related. Rates of other adverse events were similar between arms, and those that required a dose halt or dose reduction were related to methotrexate, not golimumab. There were no deaths on trial.

Merck Sharp & Dohme provided medication and unrestricted funding for the study. Dr. van Mens and two coinvestigators reported having no disclosures. Several other coinvestigators disclosed ties to UCB, AbbVie, Novartis, Janssen, Eli Lilly, and other pharmaceutical companies.

SOURCE: van Mens LJJ et al. Ann Rheum Dis. 2019 Feb 26. doi: 10.1136/annrheumdis-2018-214746.

For patients with early psoriatic arthritis, starting the tumor necrosis factor inhibitor golimumab (Simponi) at the same time as methotrexate nearly doubled the chances of remission, compared with methotrexate monotherapy, researchers reported in Annals of the Rheumatic Diseases.

In this multicenter, double-blind trial, 51 adults with CASPAR-defined psoriatic arthritis who were naive to methotrexate and biologic disease-modifying antirheumatic drugs were randomly assigned to receive monthly golimumab (50 mg subcutaneously) or placebo, in addition to methotrexate (15 mg/week, increased to 25 mg/week over 8 weeks). All patients had current active disease: At baseline, most had at least five swollen joints and at least nine tender joints.

Among 45 patients who completed the study, rates of Disease Activity Score (DAS) remission (DAS C-reactive protein score less than 1.6) at week 22 were 81% for golimumab-methotrexate and 42% for methotrexate-placebo (P = .004). “This difference in DAS remission was already observed at week 8,” wrote Leonieke J.J. van Mens, MD, of AMC/University of Amsterdam and her colleagues.

Golimumab-methotrexate also topped methotrexate monotherapy on secondary outcome measures. By week 22, median swollen joint counts were 0 with combined therapy versus 3 with methotrexate monotherapy (P = .04). Median tender joint counts were 0 and 2, respectively (P = .02). Combined golimumab-methotrexate therapy also produced significantly higher rates of low disease activity based on Disease Activity in Psoriatic Arthritis score (92% vs. 54%, respectively), Minimal Disease Activity (81% vs. 29%), and ACR20, 50, or 70 response (85% vs. 58%, 81% vs. 33%, and 58% vs. 13%, respectively).


Most differences were already statistically significant by week 8, and many were more pronounced by week 22, the researchers said. “It remains unknown if the responses – in particular the stringent responses such as remission – have already plateaued at week 22 or could even further increase over time,” they added. “Similarly, it remains to be determined if the combination of tumor necrosis factor inhibitor and methotrexate is only needed for the induction of remission or is also needed to maintain this state of remission over time.”

They explained that golimumab (or placebo) was stopped at week 22 in patients who achieved DAS CRP remission. An extension of the current study will assess whether methotrexate monotherapy can maintain responses for up to 50 weeks.

The only serious adverse event in the study occurred in the methotrexate arm and consisted of spinal stenosis that was not seen as treatment related. Rates of other adverse events were similar between arms, and those that required a dose halt or dose reduction were related to methotrexate, not golimumab. There were no deaths on trial.

Merck Sharp & Dohme provided medication and unrestricted funding for the study. Dr. van Mens and two coinvestigators reported having no disclosures. Several other coinvestigators disclosed ties to UCB, AbbVie, Novartis, Janssen, Eli Lilly, and other pharmaceutical companies.

SOURCE: van Mens LJJ et al. Ann Rheum Dis. 2019 Feb 26. doi: 10.1136/annrheumdis-2018-214746.

MAUI, HAWAII – An ongoing proof-of-concept study in the United Kingdom uses T-cell subset analysis to identify those patients with early rheumatoid arthritis who are unlikely to experience remission with methotrexate alone and therefore warrant more potent first-line therapy with a tumor necrosis factor (TNF) inhibitor in combination with methotrexate, Paul Emery, MD, said at the 2019 Rheumatology Winter Clinical Symposium.

Bruce Jancin/MDedge News

“When we get the readout from this study, if we get the results we expect, we could actually put it to the National Health Service that it would be cost saving to use biologics as first-line therapy in a proportion, which will be about 40% of patients. But we won’t necessarily need to use them for a year, and we’ll get a 70%-plus remission rate, which I think is the sort of level we should be asking for in our patients,” according to Dr. Emery, professor of rheumatology and director of the University of Leeds (England) Musculoskeletal Biomedical Research Center.

This proof-of-concept study capitalizes on earlier work by Dr. Emery and coinvestigators, who showed in 70 patients with early rheumatoid arthritis given methotrexate as their first-ever disease-modifying antirheumatic drug (DMARD) that those with a normal pretreatment frequency of naive CD4+ T cells had an 83% remission rate at 6 months as defined by a Disease Activity Score in 28 joints (DAS28) of less than 2.6. In contrast, only 21% of those with a reduced naive CD4+ T-cell frequency experienced remission when compared with healthy controls. In an analysis adjusted for age and the presence of anti–citrullinated protein antibodies (ACPA), a normal baseline naive CD4+ T-cell frequency was associated with a 5.9-fold increased likelihood of remission on methotrexate (Ann Rheum Dis. 2014 Nov;73[11]:2047-53).

In the new proof-of-concept study, DMARD-naive, ACPA-positive patients with early RA undergo T-cell subset quantification by flow cytometry. Thirty patients with a normal test result are assigned to methotrexate with treat-to-target dose escalation. Based upon the investigators’ earlier work, it’s anticipated that about 80% of these patients will be in remission at 6 months.

Sixty patients with an abnormal baseline T-cell test result are being randomized to methotrexate plus either placebo or biosimilar etanercept. Again based upon the earlier study, the expected remission rate at 6 months in the methotrexate-plus-placebo group is about 20%. In contrast, the anticipated remission rate in the patients on an anti-TNF biologic plus methotrexate as first-line therapy is about 70% on the basis of the results of previous clinical trials, including PRIZE (N Engl J Med. 2014 Nov 6;371[19]:1781-92) and COMET (Ann Rheum Dis. 2012 Jun;71[6]:989-92).

Meanwhile, the price tag for biosimilar TNF inhibitors in the United Kingdom has come down to the point that routine across-the-board use of biologics as first-line therapy is arguably cost effective, a situation Dr. Emery described as hitherto “the unthinkable.”

The cost of biosimilar adalimumab in the coming year will be less than $3,000 annually in the U.K. health care system. So if 100 patients with early RA and no contraindication to biologic therapy are placed on biosimilar adalimumab and methotrexate for 1 year, the total cost for the biologic in this cohort will be less than $300,000, and roughly 70 of the 100 patients will have achieved remission. This approach makes much more sense than current standard practice, which is to reserve biologics as second-line therapy for patients who have failed to achieve remission on nonbiologic DMARDs, thereby allowing their joint damage to advance in the interim to the point that they need to stay on biologic therapy for decades, the rheumatologist argued.

“Once one accepts that remission has become the aim of therapy, then the facts, I think, speak for themselves: There’s absolutely no doubt that the rate of remission is best with the first DMARD. So if our aim is remission, we should use that one opportunity with the best agent first, because we’re not going to get the same response later,” Dr. Emery said.

Also, “there’s no doubt” that the dose of biologics can be halved with no loss of efficacy in patients who achieve remission on full-dose therapy, as previously demonstrated in PRIZE and other trials. This strategy further reduces the overall cost of biologic therapy, he added.

Dr. Emery, who recently received the Order of the British Empire from Queen Elizabeth personally in recognition of his career achievements in rheumatology, reported having no financial conflicts of interest regarding his presentation.

bjancin@mdedge.com

MAUI, HAWAII – An ongoing proof-of-concept study in the United Kingdom uses T-cell subset analysis to identify those patients with early rheumatoid arthritis who are unlikely to experience remission with methotrexate alone and therefore warrant more potent first-line therapy with a tumor necrosis factor (TNF) inhibitor in combination with methotrexate, Paul Emery, MD, said at the 2019 Rheumatology Winter Clinical Symposium.

Bruce Jancin/MDedge News

“When we get the readout from this study, if we get the results we expect, we could actually put it to the National Health Service that it would be cost saving to use biologics as first-line therapy in a proportion, which will be about 40% of patients. But we won’t necessarily need to use them for a year, and we’ll get a 70%-plus remission rate, which I think is the sort of level we should be asking for in our patients,” according to Dr. Emery, professor of rheumatology and director of the University of Leeds (England) Musculoskeletal Biomedical Research Center.

This proof-of-concept study capitalizes on earlier work by Dr. Emery and coinvestigators, who showed in 70 patients with early rheumatoid arthritis given methotrexate as their first-ever disease-modifying antirheumatic drug (DMARD) that those with a normal pretreatment frequency of naive CD4+ T cells had an 83% remission rate at 6 months as defined by a Disease Activity Score in 28 joints (DAS28) of less than 2.6. In contrast, only 21% of those with a reduced naive CD4+ T-cell frequency experienced remission when compared with healthy controls. In an analysis adjusted for age and the presence of anti–citrullinated protein antibodies (ACPA), a normal baseline naive CD4+ T-cell frequency was associated with a 5.9-fold increased likelihood of remission on methotrexate (Ann Rheum Dis. 2014 Nov;73[11]:2047-53).

In the new proof-of-concept study, DMARD-naive, ACPA-positive patients with early RA undergo T-cell subset quantification by flow cytometry. Thirty patients with a normal test result are assigned to methotrexate with treat-to-target dose escalation. Based upon the investigators’ earlier work, it’s anticipated that about 80% of these patients will be in remission at 6 months.

Sixty patients with an abnormal baseline T-cell test result are being randomized to methotrexate plus either placebo or biosimilar etanercept. Again based upon the earlier study, the expected remission rate at 6 months in the methotrexate-plus-placebo group is about 20%. In contrast, the anticipated remission rate in the patients on an anti-TNF biologic plus methotrexate as first-line therapy is about 70% on the basis of the results of previous clinical trials, including PRIZE (N Engl J Med. 2014 Nov 6;371[19]:1781-92) and COMET (Ann Rheum Dis. 2012 Jun;71[6]:989-92).

Meanwhile, the price tag for biosimilar TNF inhibitors in the United Kingdom has come down to the point that routine across-the-board use of biologics as first-line therapy is arguably cost effective, a situation Dr. Emery described as hitherto “the unthinkable.”

The cost of biosimilar adalimumab in the coming year will be less than $3,000 annually in the U.K. health care system. So if 100 patients with early RA and no contraindication to biologic therapy are placed on biosimilar adalimumab and methotrexate for 1 year, the total cost for the biologic in this cohort will be less than $300,000, and roughly 70 of the 100 patients will have achieved remission. This approach makes much more sense than current standard practice, which is to reserve biologics as second-line therapy for patients who have failed to achieve remission on nonbiologic DMARDs, thereby allowing their joint damage to advance in the interim to the point that they need to stay on biologic therapy for decades, the rheumatologist argued.

“Once one accepts that remission has become the aim of therapy, then the facts, I think, speak for themselves: There’s absolutely no doubt that the rate of remission is best with the first DMARD. So if our aim is remission, we should use that one opportunity with the best agent first, because we’re not going to get the same response later,” Dr. Emery said.

Also, “there’s no doubt” that the dose of biologics can be halved with no loss of efficacy in patients who achieve remission on full-dose therapy, as previously demonstrated in PRIZE and other trials. This strategy further reduces the overall cost of biologic therapy, he added.

Dr. Emery, who recently received the Order of the British Empire from Queen Elizabeth personally in recognition of his career achievements in rheumatology, reported having no financial conflicts of interest regarding his presentation.

bjancin@mdedge.com

MAUI, HAWAII – An ongoing proof-of-concept study in the United Kingdom uses T-cell subset analysis to identify those patients with early rheumatoid arthritis who are unlikely to experience remission with methotrexate alone and therefore warrant more potent first-line therapy with a tumor necrosis factor (TNF) inhibitor in combination with methotrexate, Paul Emery, MD, said at the 2019 Rheumatology Winter Clinical Symposium.

Bruce Jancin/MDedge News

“When we get the readout from this study, if we get the results we expect, we could actually put it to the National Health Service that it would be cost saving to use biologics as first-line therapy in a proportion, which will be about 40% of patients. But we won’t necessarily need to use them for a year, and we’ll get a 70%-plus remission rate, which I think is the sort of level we should be asking for in our patients,” according to Dr. Emery, professor of rheumatology and director of the University of Leeds (England) Musculoskeletal Biomedical Research Center.

This proof-of-concept study capitalizes on earlier work by Dr. Emery and coinvestigators, who showed in 70 patients with early rheumatoid arthritis given methotrexate as their first-ever disease-modifying antirheumatic drug (DMARD) that those with a normal pretreatment frequency of naive CD4+ T cells had an 83% remission rate at 6 months as defined by a Disease Activity Score in 28 joints (DAS28) of less than 2.6. In contrast, only 21% of those with a reduced naive CD4+ T-cell frequency experienced remission when compared with healthy controls. In an analysis adjusted for age and the presence of anti–citrullinated protein antibodies (ACPA), a normal baseline naive CD4+ T-cell frequency was associated with a 5.9-fold increased likelihood of remission on methotrexate (Ann Rheum Dis. 2014 Nov;73[11]:2047-53).

In the new proof-of-concept study, DMARD-naive, ACPA-positive patients with early RA undergo T-cell subset quantification by flow cytometry. Thirty patients with a normal test result are assigned to methotrexate with treat-to-target dose escalation. Based upon the investigators’ earlier work, it’s anticipated that about 80% of these patients will be in remission at 6 months.

Sixty patients with an abnormal baseline T-cell test result are being randomized to methotrexate plus either placebo or biosimilar etanercept. Again based upon the earlier study, the expected remission rate at 6 months in the methotrexate-plus-placebo group is about 20%. In contrast, the anticipated remission rate in the patients on an anti-TNF biologic plus methotrexate as first-line therapy is about 70% on the basis of the results of previous clinical trials, including PRIZE (N Engl J Med. 2014 Nov 6;371[19]:1781-92) and COMET (Ann Rheum Dis. 2012 Jun;71[6]:989-92).

Meanwhile, the price tag for biosimilar TNF inhibitors in the United Kingdom has come down to the point that routine across-the-board use of biologics as first-line therapy is arguably cost effective, a situation Dr. Emery described as hitherto “the unthinkable.”

The cost of biosimilar adalimumab in the coming year will be less than $3,000 annually in the U.K. health care system. So if 100 patients with early RA and no contraindication to biologic therapy are placed on biosimilar adalimumab and methotrexate for 1 year, the total cost for the biologic in this cohort will be less than $300,000, and roughly 70 of the 100 patients will have achieved remission. This approach makes much more sense than current standard practice, which is to reserve biologics as second-line therapy for patients who have failed to achieve remission on nonbiologic DMARDs, thereby allowing their joint damage to advance in the interim to the point that they need to stay on biologic therapy for decades, the rheumatologist argued.

“Once one accepts that remission has become the aim of therapy, then the facts, I think, speak for themselves: There’s absolutely no doubt that the rate of remission is best with the first DMARD. So if our aim is remission, we should use that one opportunity with the best agent first, because we’re not going to get the same response later,” Dr. Emery said.

Also, “there’s no doubt” that the dose of biologics can be halved with no loss of efficacy in patients who achieve remission on full-dose therapy, as previously demonstrated in PRIZE and other trials. This strategy further reduces the overall cost of biologic therapy, he added.

Dr. Emery, who recently received the Order of the British Empire from Queen Elizabeth personally in recognition of his career achievements in rheumatology, reported having no financial conflicts of interest regarding his presentation.

bjancin@mdedge.com

The Food and Drug Administration has approved Gloperba, the first liquid formulation of the gout drug colchicine, for prophylaxis of gout flares in adults, according to a statement from Romeg Therapeutics.

Colchicine has been used in capsule and tablet forms to treat this form of arthritis for decades. An advantage to the new formulation is that it allows physicians to “easily make dose adjustments,” according to the statement.

“Existing therapies do not adequately address the physician’s need to adjust dosages of colchicine to manage the toxicity profile for patients with renal and liver impairments, side effects, common drug-to-drug interactions, and age-related health disorders,” said Naomi Vishnupad, PhD, chief scientific officer of Romeg Therapeutics, in the statement.

According to the prescribing information for the drug on the FDA website, this formulation is indicated for prophylaxis rather than acute treatment of gout flares because the safety profile of acute treatment with it has not yet been studied. It is contraindicated in patients with hepatic and/or renal impairment. Gastrointestinal symptoms were the most commonly reported adverse reactions.

The drug is expected to be available this summer.

cpalmer@mdedge.com

The Food and Drug Administration has approved Gloperba, the first liquid formulation of the gout drug colchicine, for prophylaxis of gout flares in adults, according to a statement from Romeg Therapeutics.

Colchicine has been used in capsule and tablet forms to treat this form of arthritis for decades. An advantage to the new formulation is that it allows physicians to “easily make dose adjustments,” according to the statement.

“Existing therapies do not adequately address the physician’s need to adjust dosages of colchicine to manage the toxicity profile for patients with renal and liver impairments, side effects, common drug-to-drug interactions, and age-related health disorders,” said Naomi Vishnupad, PhD, chief scientific officer of Romeg Therapeutics, in the statement.

According to the prescribing information for the drug on the FDA website, this formulation is indicated for prophylaxis rather than acute treatment of gout flares because the safety profile of acute treatment with it has not yet been studied. It is contraindicated in patients with hepatic and/or renal impairment. Gastrointestinal symptoms were the most commonly reported adverse reactions.

The drug is expected to be available this summer.

cpalmer@mdedge.com

The Food and Drug Administration has approved Gloperba, the first liquid formulation of the gout drug colchicine, for prophylaxis of gout flares in adults, according to a statement from Romeg Therapeutics.

Colchicine has been used in capsule and tablet forms to treat this form of arthritis for decades. An advantage to the new formulation is that it allows physicians to “easily make dose adjustments,” according to the statement.

“Existing therapies do not adequately address the physician’s need to adjust dosages of colchicine to manage the toxicity profile for patients with renal and liver impairments, side effects, common drug-to-drug interactions, and age-related health disorders,” said Naomi Vishnupad, PhD, chief scientific officer of Romeg Therapeutics, in the statement.

According to the prescribing information for the drug on the FDA website, this formulation is indicated for prophylaxis rather than acute treatment of gout flares because the safety profile of acute treatment with it has not yet been studied. It is contraindicated in patients with hepatic and/or renal impairment. Gastrointestinal symptoms were the most commonly reported adverse reactions.

The drug is expected to be available this summer.

cpalmer@mdedge.com

Vagus nerve stimulation – an established treatment for refractory epilepsy and depression – is slowly gaining momentum in rheumatology.

The work is being led by SetPoint Medical, a small company in Valencia, Calif., just north of Los Angeles. Its vagus nerve stimulation (VNS) device, dubbed the microregulator, has been implanted in 14 patients with refractory rheumatoid arthritis (RA) in the company’s initial safety study.

Courtesy Dr. David Chernoff

The microregulator is a small lithium ion battery encased in an inert silastic pod; it’s surgically implanted to sit atop the vagus nerve in the left side of the neck, and delivers an electrical pulse at set intervals. Data from the 12-week, sham-controlled safety study is set to be unblinded in coming weeks. A pivotal trial also is in the works, perhaps to start in late 2019, according to rheumatologist and SetPoint’s Chief Medical Officer David Chernoff, MD.

Although SetPoint is ahead of the pack, it’s not alone. ElectroCore, a biotech company in Basking Ridge, N.J., has expressed interest in pursuing rheumatoid arthritis and Sjögren’s syndrome indications for its gammaCore device, a vagus nerve stimulator patients apply to the neck. It’s already on the market for migraines and cluster headaches.

Researchers recently reported a small decrease in 28-joint Disease Activity Score using C-reactive protein (DAS28-CRP) results after 16 RA patients with flares used the device for 4 days (Ann Rheum Dis. 2018;77:1401. Abstract AB0481). In another recent open-label study, 15 women with Sjögren’s reported less fatigue while using the device for a month (Arthritis Rheumatol. 2017;69[suppl 10]: Abstract 563).

Meanwhile, The Feinstein Institute for Medical Research, based in Manhasset, N.Y., on Long Island, recently reported positive outcomes in 18 patients with systemic lupus erythematosus, using its own novel device, which stimulates the vagus nerve through the ear lobe. VNS was delivered for 5 minutes per day for 4 days (Arthritis Rheumatol. 2018;70[suppl 10]: Abstract 2652).

On day 5, patients who received VNS, versus sham patients in whom the device was not turned on, had a significant decrease in pain, fatigue, and joint scores. The investigators concluded that “additional studies evaluating this promising intervention and its potential mechanisms are warranted.”

“We are clearly ahead of everybody because we’ve already implanted people, but I think it’s good for the field if more people are chasing this. The more resources that are put into it, the more we can show that this approach actually works,” said SetPoint’s Dr. Chernoff.

The hope

In general, interest in VNS for rheumatology is being driven by the possibility that it may reduce proinflammatory cytokines, which opens the door for VNS as an alternative to biologics. The hope is that instead of going after tumor necrosis factor and other cytokines one at a time, VNS could be used to target a range of cytokines all at once, without the cost and side effects of biologics.

“It seems so dramatically different” from what rheumatologists have done in the past, “that our first instinct is to say ‘oh, that’s ridiculous,’ but the science behind it is actually not bad. There may indeed be something to this,” said rheumatologist Joel Kremer, MD, Pfaff Family Professor of Medicine at Albany (N.Y.) Medical College.

Dr. Kremer reviewed SetPoint’s early scientific data after being asked by the company to participate in the safety study; he declined for logistical reasons.

He noted that “there are some strange interactions between the CNS and inflammatory disease.” When RA patients have a stroke, for instance, RA goes into remission on the side of their body affected by the stroke. “That’s been known for decades, but we really don’t understand what’s going on there,” Dr. Kremer said.

The evidence

Perhaps the strongest evidence to date for VNS as a cytokine blocker in rheumatology comes from an open-label, 12-week study, also conducted by SetPoint, in 17 patients with active RA despite methotrexate treatment; some had failed biologics (Proc Natl Acad Sci U S A. 2016 Jul 19;113[29]:8284-9. doi: 10.1073/pnas.160563511).

The microregulator wasn’t ready yet, so investigators implanted a VNS system commercially available for epilepsy and reprogrammed it to deliver a 60-second pulse once a day to the left cervical vagus nerve, which was increased after a month to four 60-second stimulations a day in nonresponders.

The investigators “observed that TNF production in cultured peripheral blood obtained ... on day 42 was significantly reduced from” 21 days before the study was started (TNF 2,900 pg/mL on day –21, versus 1,776 pg/mL on day 42; P less than .05).

When VNS was shut off, TNF production increased; when it was turned back on, it dropped. Interleukin 6 also fell significantly among responders. Overall, DAS28-CRP scores fell about 1.5 points on the 10-point scale from baseline to week 12.

Two-year outcomes were recently reported (Ann Rheum Dis. 2018;77:981-2. Abstract SAT0240). All 17 patients elected to continue treatment after the initial 12 weeks. Biologics were added in nine subjects (53%), because of no or limited response to VNS. Investigators were free to change the VNS dosing regimen, which varied during the study extension up to eight 60-second bursts a day. The roughly 1.5-point improvement in DAS28-CRP was maintained at 2 years.

“These long-term data suggest that bioelectronic therapy may be used as an alternative to, or in combination with, biological[s],” concluded Dr. Chernoff and other study team members.

Awaiting more data

When asked for comment, Daniel E. Furst, MD, professor of medicine (emeritus) at the University of California, Los Angeles, said “there certainly are neurotropic factors” at play in rheumatology, “so there’s sort of a potential reason why” VNS might work, “but we need to understand far more about its mechanism, and [remember] that open-label studies are not to be believed until” large, randomized, blinded, placebo-controlled studies are done.

Dr. Furst also is an adjunct professor at the University of Washington, Seattle, and a research professor at the University of Florence (Italy). He is in part-time practice in Los Angeles and Seattle.

If everything works out, however, “the vagus nerve may give us a much wider opportunity to block a host of cytokines; it may change the whole paradigm of how we manage rheumatoid arthritis. I think this is possibly a groundbreaking new therapeutic area, much in the way the biologics were” 20 years ago, said rheumatologist Norman B. Gaylis, MD.

Courtesy Dr. Norman B. Gaylis

Several of the 14 patients in SetPoint’s safety study were enrolled at Dr. Gaylis’s practice in Aventura, Fla., just north of Miami; he said he is eagerly awaiting for the results to be unblinded. If clinical response in that study and others correlates with a cytokine response, “that’s going to be big, and very significant” in the rheumatology community, he said.

SetPoint’s microregulator is charged wirelessly through a collar patients wear for a few minutes once a week. Dosing can also be adjusted through the collar with the help of a computer application.

The device wasn’t turned on in 4 of the 14 patients in the safety study, as a sham control, but shamming was problematic because patients can potentially feel VNS as a buzz or a change in their voice. To get around that potential confounder, both sham and treated patients were told they might or might not feel something during the study.

Implantation takes about an hour, and is much less complex than implanting currently available epilepsy VNS systems, which require implantation of both a power source on the chest wall and wire coils on the vagus nerve.

Cardiac concerns are the main safety issue with VNS, beyond the surgery itself. Cardiac monitoring was done in the safety study to “ensure that we did not cause things like bradycardia, heart block, syncope, etc.” Dr. Chernoff said. So far, they haven’t turned out to be a problem.

Dr. Furst and Dr. Kremer had no relevant disclosures. Dr. Gaylis was compensated by SetPoint for participating in the safety study; he is a consultant and investigator for Electrocore. Dr. Furst and Dr. Gaylis are members of the editorial advisory board for MDedge Rheumatology/Rheumatology News.

aotto@mdedge.com

Vagus nerve stimulation – an established treatment for refractory epilepsy and depression – is slowly gaining momentum in rheumatology.

The work is being led by SetPoint Medical, a small company in Valencia, Calif., just north of Los Angeles. Its vagus nerve stimulation (VNS) device, dubbed the microregulator, has been implanted in 14 patients with refractory rheumatoid arthritis (RA) in the company’s initial safety study.

Courtesy Dr. David Chernoff

The microregulator is a small lithium ion battery encased in an inert silastic pod; it’s surgically implanted to sit atop the vagus nerve in the left side of the neck, and delivers an electrical pulse at set intervals. Data from the 12-week, sham-controlled safety study is set to be unblinded in coming weeks. A pivotal trial also is in the works, perhaps to start in late 2019, according to rheumatologist and SetPoint’s Chief Medical Officer David Chernoff, MD.

Although SetPoint is ahead of the pack, it’s not alone. ElectroCore, a biotech company in Basking Ridge, N.J., has expressed interest in pursuing rheumatoid arthritis and Sjögren’s syndrome indications for its gammaCore device, a vagus nerve stimulator patients apply to the neck. It’s already on the market for migraines and cluster headaches.

Researchers recently reported a small decrease in 28-joint Disease Activity Score using C-reactive protein (DAS28-CRP) results after 16 RA patients with flares used the device for 4 days (Ann Rheum Dis. 2018;77:1401. Abstract AB0481). In another recent open-label study, 15 women with Sjögren’s reported less fatigue while using the device for a month (Arthritis Rheumatol. 2017;69[suppl 10]: Abstract 563).

Meanwhile, The Feinstein Institute for Medical Research, based in Manhasset, N.Y., on Long Island, recently reported positive outcomes in 18 patients with systemic lupus erythematosus, using its own novel device, which stimulates the vagus nerve through the ear lobe. VNS was delivered for 5 minutes per day for 4 days (Arthritis Rheumatol. 2018;70[suppl 10]: Abstract 2652).

On day 5, patients who received VNS, versus sham patients in whom the device was not turned on, had a significant decrease in pain, fatigue, and joint scores. The investigators concluded that “additional studies evaluating this promising intervention and its potential mechanisms are warranted.”

“We are clearly ahead of everybody because we’ve already implanted people, but I think it’s good for the field if more people are chasing this. The more resources that are put into it, the more we can show that this approach actually works,” said SetPoint’s Dr. Chernoff.

The hope

In general, interest in VNS for rheumatology is being driven by the possibility that it may reduce proinflammatory cytokines, which opens the door for VNS as an alternative to biologics. The hope is that instead of going after tumor necrosis factor and other cytokines one at a time, VNS could be used to target a range of cytokines all at once, without the cost and side effects of biologics.

“It seems so dramatically different” from what rheumatologists have done in the past, “that our first instinct is to say ‘oh, that’s ridiculous,’ but the science behind it is actually not bad. There may indeed be something to this,” said rheumatologist Joel Kremer, MD, Pfaff Family Professor of Medicine at Albany (N.Y.) Medical College.

Dr. Kremer reviewed SetPoint’s early scientific data after being asked by the company to participate in the safety study; he declined for logistical reasons.

He noted that “there are some strange interactions between the CNS and inflammatory disease.” When RA patients have a stroke, for instance, RA goes into remission on the side of their body affected by the stroke. “That’s been known for decades, but we really don’t understand what’s going on there,” Dr. Kremer said.

The evidence

Perhaps the strongest evidence to date for VNS as a cytokine blocker in rheumatology comes from an open-label, 12-week study, also conducted by SetPoint, in 17 patients with active RA despite methotrexate treatment; some had failed biologics (Proc Natl Acad Sci U S A. 2016 Jul 19;113[29]:8284-9. doi: 10.1073/pnas.160563511).

The microregulator wasn’t ready yet, so investigators implanted a VNS system commercially available for epilepsy and reprogrammed it to deliver a 60-second pulse once a day to the left cervical vagus nerve, which was increased after a month to four 60-second stimulations a day in nonresponders.

The investigators “observed that TNF production in cultured peripheral blood obtained ... on day 42 was significantly reduced from” 21 days before the study was started (TNF 2,900 pg/mL on day –21, versus 1,776 pg/mL on day 42; P less than .05).

When VNS was shut off, TNF production increased; when it was turned back on, it dropped. Interleukin 6 also fell significantly among responders. Overall, DAS28-CRP scores fell about 1.5 points on the 10-point scale from baseline to week 12.

Two-year outcomes were recently reported (Ann Rheum Dis. 2018;77:981-2. Abstract SAT0240). All 17 patients elected to continue treatment after the initial 12 weeks. Biologics were added in nine subjects (53%), because of no or limited response to VNS. Investigators were free to change the VNS dosing regimen, which varied during the study extension up to eight 60-second bursts a day. The roughly 1.5-point improvement in DAS28-CRP was maintained at 2 years.

“These long-term data suggest that bioelectronic therapy may be used as an alternative to, or in combination with, biological[s],” concluded Dr. Chernoff and other study team members.

Awaiting more data

When asked for comment, Daniel E. Furst, MD, professor of medicine (emeritus) at the University of California, Los Angeles, said “there certainly are neurotropic factors” at play in rheumatology, “so there’s sort of a potential reason why” VNS might work, “but we need to understand far more about its mechanism, and [remember] that open-label studies are not to be believed until” large, randomized, blinded, placebo-controlled studies are done.

Dr. Furst also is an adjunct professor at the University of Washington, Seattle, and a research professor at the University of Florence (Italy). He is in part-time practice in Los Angeles and Seattle.

If everything works out, however, “the vagus nerve may give us a much wider opportunity to block a host of cytokines; it may change the whole paradigm of how we manage rheumatoid arthritis. I think this is possibly a groundbreaking new therapeutic area, much in the way the biologics were” 20 years ago, said rheumatologist Norman B. Gaylis, MD.

Courtesy Dr. Norman B. Gaylis

Several of the 14 patients in SetPoint’s safety study were enrolled at Dr. Gaylis’s practice in Aventura, Fla., just north of Miami; he said he is eagerly awaiting for the results to be unblinded. If clinical response in that study and others correlates with a cytokine response, “that’s going to be big, and very significant” in the rheumatology community, he said.

SetPoint’s microregulator is charged wirelessly through a collar patients wear for a few minutes once a week. Dosing can also be adjusted through the collar with the help of a computer application.

The device wasn’t turned on in 4 of the 14 patients in the safety study, as a sham control, but shamming was problematic because patients can potentially feel VNS as a buzz or a change in their voice. To get around that potential confounder, both sham and treated patients were told they might or might not feel something during the study.

Implantation takes about an hour, and is much less complex than implanting currently available epilepsy VNS systems, which require implantation of both a power source on the chest wall and wire coils on the vagus nerve.

Cardiac concerns are the main safety issue with VNS, beyond the surgery itself. Cardiac monitoring was done in the safety study to “ensure that we did not cause things like bradycardia, heart block, syncope, etc.” Dr. Chernoff said. So far, they haven’t turned out to be a problem.

Dr. Furst and Dr. Kremer had no relevant disclosures. Dr. Gaylis was compensated by SetPoint for participating in the safety study; he is a consultant and investigator for Electrocore. Dr. Furst and Dr. Gaylis are members of the editorial advisory board for MDedge Rheumatology/Rheumatology News.

aotto@mdedge.com

Vagus nerve stimulation – an established treatment for refractory epilepsy and depression – is slowly gaining momentum in rheumatology.

The work is being led by SetPoint Medical, a small company in Valencia, Calif., just north of Los Angeles. Its vagus nerve stimulation (VNS) device, dubbed the microregulator, has been implanted in 14 patients with refractory rheumatoid arthritis (RA) in the company’s initial safety study.

Courtesy Dr. David Chernoff

The microregulator is a small lithium ion battery encased in an inert silastic pod; it’s surgically implanted to sit atop the vagus nerve in the left side of the neck, and delivers an electrical pulse at set intervals. Data from the 12-week, sham-controlled safety study is set to be unblinded in coming weeks. A pivotal trial also is in the works, perhaps to start in late 2019, according to rheumatologist and SetPoint’s Chief Medical Officer David Chernoff, MD.

Although SetPoint is ahead of the pack, it’s not alone. ElectroCore, a biotech company in Basking Ridge, N.J., has expressed interest in pursuing rheumatoid arthritis and Sjögren’s syndrome indications for its gammaCore device, a vagus nerve stimulator patients apply to the neck. It’s already on the market for migraines and cluster headaches.

Researchers recently reported a small decrease in 28-joint Disease Activity Score using C-reactive protein (DAS28-CRP) results after 16 RA patients with flares used the device for 4 days (Ann Rheum Dis. 2018;77:1401. Abstract AB0481). In another recent open-label study, 15 women with Sjögren’s reported less fatigue while using the device for a month (Arthritis Rheumatol. 2017;69[suppl 10]: Abstract 563).

Meanwhile, The Feinstein Institute for Medical Research, based in Manhasset, N.Y., on Long Island, recently reported positive outcomes in 18 patients with systemic lupus erythematosus, using its own novel device, which stimulates the vagus nerve through the ear lobe. VNS was delivered for 5 minutes per day for 4 days (Arthritis Rheumatol. 2018;70[suppl 10]: Abstract 2652).

On day 5, patients who received VNS, versus sham patients in whom the device was not turned on, had a significant decrease in pain, fatigue, and joint scores. The investigators concluded that “additional studies evaluating this promising intervention and its potential mechanisms are warranted.”

“We are clearly ahead of everybody because we’ve already implanted people, but I think it’s good for the field if more people are chasing this. The more resources that are put into it, the more we can show that this approach actually works,” said SetPoint’s Dr. Chernoff.

The hope

In general, interest in VNS for rheumatology is being driven by the possibility that it may reduce proinflammatory cytokines, which opens the door for VNS as an alternative to biologics. The hope is that instead of going after tumor necrosis factor and other cytokines one at a time, VNS could be used to target a range of cytokines all at once, without the cost and side effects of biologics.

“It seems so dramatically different” from what rheumatologists have done in the past, “that our first instinct is to say ‘oh, that’s ridiculous,’ but the science behind it is actually not bad. There may indeed be something to this,” said rheumatologist Joel Kremer, MD, Pfaff Family Professor of Medicine at Albany (N.Y.) Medical College.

Dr. Kremer reviewed SetPoint’s early scientific data after being asked by the company to participate in the safety study; he declined for logistical reasons.

He noted that “there are some strange interactions between the CNS and inflammatory disease.” When RA patients have a stroke, for instance, RA goes into remission on the side of their body affected by the stroke. “That’s been known for decades, but we really don’t understand what’s going on there,” Dr. Kremer said.

The evidence

Perhaps the strongest evidence to date for VNS as a cytokine blocker in rheumatology comes from an open-label, 12-week study, also conducted by SetPoint, in 17 patients with active RA despite methotrexate treatment; some had failed biologics (Proc Natl Acad Sci U S A. 2016 Jul 19;113[29]:8284-9. doi: 10.1073/pnas.160563511).

The microregulator wasn’t ready yet, so investigators implanted a VNS system commercially available for epilepsy and reprogrammed it to deliver a 60-second pulse once a day to the left cervical vagus nerve, which was increased after a month to four 60-second stimulations a day in nonresponders.

The investigators “observed that TNF production in cultured peripheral blood obtained ... on day 42 was significantly reduced from” 21 days before the study was started (TNF 2,900 pg/mL on day –21, versus 1,776 pg/mL on day 42; P less than .05).

When VNS was shut off, TNF production increased; when it was turned back on, it dropped. Interleukin 6 also fell significantly among responders. Overall, DAS28-CRP scores fell about 1.5 points on the 10-point scale from baseline to week 12.

Two-year outcomes were recently reported (Ann Rheum Dis. 2018;77:981-2. Abstract SAT0240). All 17 patients elected to continue treatment after the initial 12 weeks. Biologics were added in nine subjects (53%), because of no or limited response to VNS. Investigators were free to change the VNS dosing regimen, which varied during the study extension up to eight 60-second bursts a day. The roughly 1.5-point improvement in DAS28-CRP was maintained at 2 years.

“These long-term data suggest that bioelectronic therapy may be used as an alternative to, or in combination with, biological[s],” concluded Dr. Chernoff and other study team members.

Awaiting more data

When asked for comment, Daniel E. Furst, MD, professor of medicine (emeritus) at the University of California, Los Angeles, said “there certainly are neurotropic factors” at play in rheumatology, “so there’s sort of a potential reason why” VNS might work, “but we need to understand far more about its mechanism, and [remember] that open-label studies are not to be believed until” large, randomized, blinded, placebo-controlled studies are done.

Dr. Furst also is an adjunct professor at the University of Washington, Seattle, and a research professor at the University of Florence (Italy). He is in part-time practice in Los Angeles and Seattle.

If everything works out, however, “the vagus nerve may give us a much wider opportunity to block a host of cytokines; it may change the whole paradigm of how we manage rheumatoid arthritis. I think this is possibly a groundbreaking new therapeutic area, much in the way the biologics were” 20 years ago, said rheumatologist Norman B. Gaylis, MD.

Courtesy Dr. Norman B. Gaylis

Several of the 14 patients in SetPoint’s safety study were enrolled at Dr. Gaylis’s practice in Aventura, Fla., just north of Miami; he said he is eagerly awaiting for the results to be unblinded. If clinical response in that study and others correlates with a cytokine response, “that’s going to be big, and very significant” in the rheumatology community, he said.

SetPoint’s microregulator is charged wirelessly through a collar patients wear for a few minutes once a week. Dosing can also be adjusted through the collar with the help of a computer application.

The device wasn’t turned on in 4 of the 14 patients in the safety study, as a sham control, but shamming was problematic because patients can potentially feel VNS as a buzz or a change in their voice. To get around that potential confounder, both sham and treated patients were told they might or might not feel something during the study.

Implantation takes about an hour, and is much less complex than implanting currently available epilepsy VNS systems, which require implantation of both a power source on the chest wall and wire coils on the vagus nerve.

Cardiac concerns are the main safety issue with VNS, beyond the surgery itself. Cardiac monitoring was done in the safety study to “ensure that we did not cause things like bradycardia, heart block, syncope, etc.” Dr. Chernoff said. So far, they haven’t turned out to be a problem.

Dr. Furst and Dr. Kremer had no relevant disclosures. Dr. Gaylis was compensated by SetPoint for participating in the safety study; he is a consultant and investigator for Electrocore. Dr. Furst and Dr. Gaylis are members of the editorial advisory board for MDedge Rheumatology/Rheumatology News.

aotto@mdedge.com

Laboratory tests are often ordered inappropriately for patients in whom a rheumatologic illness is suspected; this occurs in both primary and secondary care.¹ Some tests are available both singly and as part of a battery of tests screening healthy people without symptoms.

The problem: negative test results are by no means always reassuring, and false-positive results raise the risks of unnecessary anxiety for patients and clinicians, needless referrals, and potential morbidity due to further unnecessary testing and exposure to wrong treatments.² Clinicians should be aware of the pitfalls of these tests in order to choose them wisely and interpret the results correctly.

This article provides practical guidance on requesting and interpreting some common tests in rheumatology, with the aid of case vignettes.

RHEUMATOID FACTOR AND ANTICITRULLINATED PEPTIDE ANTIBODY

A 41-year-old woman, previously in good health, presents to her primary care practitioner with a 6-week history of pain and swelling in her hands and early morning stiffness lasting about 2 hours. She denies having any extraarticular symptoms. Physical examination reveals synovitis across her right metacarpophalangeal joints, proximal interphalangeal joint of the left middle finger, and left wrist. The primary care physician is concerned that her symptoms might be due to rheumatoid arthritis.

Would testing for rheumatoid factor and anticitrullinated peptide antibody be useful in this patient?

Rheumatoid factor is an antibody (immunoglobulin M, IgG, or IgA) targeted against the Fc fragment of IgG.³ It was so named because it was originally detected in patients with rheumatoid arthritis, but it is neither sensitive nor specific for this condition. A meta-analysis of more than 5,000 patients with rheumatoid arthritis reported that rheumatoid factor testing had a sensitivity of 69% and specificity of 85%.⁴

Anticitrullinated peptide antibody, on the other hand, is much more specific for rheumatoid arthritis (95%), as it is seldom seen in other conditions, but its sensitivity is similar to that of rheumatoid factor (68%).^4–6 A positive result would thus lend strength to the diagnosis of rheumatoid arthritis, but a negative result would not exclude it.

Approach to early arthritis

When faced with a patient with early arthritis, some key questions to ask include^7,8:

Is this an inflammatory or a mechanical problem? Inflammatory arthritis is suggested by joint swelling that is not due to trauma or bony hypertrophy, early morning stiffness lasting longer than 30 minutes, and elevated inflammatory markers (erythrocyte sedimentation rate or C-reactive protein). Involvement of the small joints of the hands and feet may be suggested by pain on compression of the metacarpophalangeal and metatarsophalangeal joints, respectively.

Is there a definite identifiable underlying cause for the inflammatory arthritis? The pattern of development of joint symptoms or the presence of extraarticular symptoms may suggest an underlying problem such as gout, psoriatic arthritis, systemic lupus erythematosus, or sarcoidosis.

If the arthritis is undifferentiated (ie, there is no definite identifiable cause), is it likely to remit or persist? This is perhaps the most important question to ask in order to prognosticate. Patients with risk factors for persistent disease, ie, for development of rheumatoid arthritis, should be referred to a rheumatologist early for timely institution of disease-modifying antirheumatic drug therapy.⁹ Multiple studies have shown that patients in whom this therapy is started early have much better clinical, functional, and radiologic outcomes than those in whom it is delayed.^10–12

The revised American College of Rheumatology and European League Against Rheumatism criteria¹³ include the following factors as predictors of persistence:

• Number of involved joints (with greater weight given to involvement of small joints)
• Duration of symptoms 6 weeks or longer
• Elevated acute-phase response (erythrocyte sedimentation rate or C-reactive protein level)
• A positive serologic test (either rheumatoid factor or anticitrullinated peptide antibody).

If both rheumatoid factor and anticitrullinated peptide antibody are positive in a patient with early undifferentiated arthritis, the risk of progression to rheumatoid arthritis is almost 100%, thus underscoring the importance of testing for these antibodies.^5,6 Referral to a rheumatologist should, however, not be delayed in patients with negative test results (more than one-third of patients with rheumatoid arthritis may be negative for both), and should be considered in those with inflammatory joint symptoms persisting longer than 6 weeks, especially with involvement of the small joints (sparing the distal interphalangeals) and elevated acute-phase response.

Rheumatoid factor in healthy people without symptoms

In some countries, testing for rheumatoid factor is offered as part of a battery of screening tests in healthy people who have no symptoms, a practice that should be strongly discouraged.

Multiple studies, both prospective and retrospective, have demonstrated that both rheumatoid factor and anticitrullinated peptide antibody may be present several years before the clinical diagnosis of rheumatoid arthritis.^6,14–16 But the risk of developing rheumatoid arthritis for asymptomatic individuals who are rheumatoid factor-positive depends on the rheumatoid factor titer, positive family history of rheumatoid arthritis in first-degree relatives, and copresence of anticitrullinated peptide antibody. The absolute risk, nevertheless, is still very small. In some, there might be an alternative explanation such as undiagnosed Sjögren syndrome or hepatitis C.

In any event, no strategy is currently available that is proven to prevent the development of rheumatoid arthritis, and there is no role for disease-modifying therapy during the preclinical phase.¹⁶

Back to our patient

Blood testing in our patient reveals normal complete blood cell counts, aminotransferase levels, and serum creatinine concentration; findings on urinalysis are normal. Her erythrocyte sedimentation rate is 56 mm/hour (reference range 0–15), and her C-reactive protein level is 26 mg/dL (normal < 3). Testing is negative for rheumatoid factor and anticitrullinated peptide antibody.

Although her rheumatoid factor and anticitrullinated peptide antibody tests are negative, she is referred to a rheumatologist because she has predictors of persistent disease, ie, symptom duration of 6 weeks, involvement of the small joints of the hands, and elevated erythrocyte sedimentation rate and C-reactive protein. The rheumatologist checks her parvovirus serology, which is negative.

The patient is given parenteral depot corticosteroid therapy, to which she responds briefly. Because her symptoms persist and continue to worsen, methotrexate treatment is started after an additional 6 weeks.

A 37-year-old woman presents to her primary care physician with the complaint of tiredness. She has a family history of systemic lupus erythematosus in her sister and maternal aunt. She is understandably worried about lupus because of the family history and is asking to be tested for it.

Would testing for antinuclear antibody be reasonable?

Antinuclear antibody is not a single antibody but rather a family of autoantibodies that are directed against nuclear constituents such as single- or double-stranded deoxyribonucleic acid (dsDNA), histones, centromeres, proteins complexed with ribonucleic acid (RNA), and enzymes such as topoisomerase.^17,18

Protein antigens complexed with RNA and some enzymes in the nucleus are also known as extractable nuclear antigens (ENAs). They include Ro, La, Sm, Jo-1, RNP, and ScL-70 and are named after the patient in whom they were first discovered (Robert, Lavine, Smith, and John), the antigen that is targeted (ribonucleoprotein or RNP), and the disease with which they are associated (anti-ScL-70 or antitopoisomerase in diffuse cutaneous scleroderma).

Antinuclear antibody testing is commonly requested to exclude connective tissue diseases such as lupus, but the clinician needs to be aware of the following points:

Antinuclear antibody may be encountered in conditions other than lupus

These include¹⁹:

• Other autoimmune diseases such as rheumatoid arthritis, primary Sjögren syndrome, systemic sclerosis, autoimmune thyroid disease, and myasthenia gravis
• Infection with organisms that share the epitope with self-antigens (molecular mimicry)
• Cancers
• Drugs such as hydralazine, procainamide, and minocycline.

Antinuclear antibody might also be produced by the healthy immune system from time to time to clear the nuclear debris that is extruded from aging cells.

A study in healthy individuals²⁰ reported a prevalence of positive antinuclear antibody of 32% at a titer of 1/40, 15% at a titer of 1/80, 7% at a titer of 1/160, and 3% at a titer of 1/320. Importantly, a positive result was more common among family members of patients with autoimmune connective tissue diseases.²¹ Hence, a positive antinuclear antibody result does not always mean lupus.

Antinuclear antibody testing is highly sensitive for lupus

With current laboratory methods, antinuclear antibody testing has a sensitivity close to 100%. Hence, a negative result virtually rules out lupus.

Two methods are commonly used to test for antinuclear antibody: indirect immunofluorescence and enzyme-linked immunosorbent assay (ELISA).²² While human epithelial (Hep2) cells are used as the source of antigen in immunofluorescence, purified nuclear antigens coated on multiple-well plates are used in ELISA.

Although ELISA is simpler to perform, immunofluorescence has a slightly better sensitivity (because the Hep2 cells express a wide range of antigens) and is still considered the gold standard. As expected, the higher sensitivity occurs at the cost of reduced specificity (about 60%), so antinuclear antibody will also be detected in all the other conditions listed above.²³

To improve the specificity of antinuclear antibody testing, laboratories report titers (the highest dilution of the test serum that tested positive); a cutoff of greater than 1/80 is generally considered significant.

Do not order antinuclear antibody testing indiscriminately

To sum up, the antinuclear antibody test should be requested only in patients with involvement of multiple organ systems. Although a negative result would make it extremely unlikely that the clinical presentation is due to lupus, a positive result is insufficient on its own to make a diagnosis of lupus.

Diagnosing lupus is straightforward when patients present with a specific manifestation such as inflammatory arthritis, photosensitive skin rash, hemolytic anemia, thrombocytopenia, or nephritis, or with specific antibodies such as those against dsDNA or Sm. Patients who present with nonspecific symptoms such as arthralgia or tiredness with a positive antinuclear antibody and negative anti-dsDNA and anti-Sm may present difficulties even for the specialist.^25–27

Back to our patient

Our patient denies arthralgia. She has no extraarticular symptoms such as skin rashes, oral ulcers, sicca symptoms, muscle weakness, Raynaud phenomenon, pleuritic chest pain, or breathlessness. Findings on physical examination and urinalysis are unremarkable.

Her primary care physician decides to check her complete blood cell count, erythrocyte sedimentation rate, and thyroid-stimulating hormone level. Although she is reassured that her tiredness is not due to lupus, she insists on getting an antinuclear antibody test.

Her complete blood cell counts are normal. Her erythrocyte sedimentation rate is 6 mm/hour. However, her thyroid-stimulating hormone level is elevated, and subsequent testing shows low free thyroxine and positive thyroid peroxidase antibodies. The antinuclear antibody is positive in a titer of 1/80 and negative for anti-dsDNA and anti-ENA.

We explain to her that the positive antinuclear antibody is most likely related to her autoimmune thyroid disease. She is referred to an endocrinologist.

A 24-year-old woman presents to the emergency department with acute unprovoked deep vein thrombosis in her right leg, confirmed by ultrasonography. She has no history of previous thrombosis, and the relevant family history is unremarkable. She has never been pregnant. Her platelet count is 84 × 10⁹/L (reference range 150–400), and her baseline activated partial thromboplastin time is prolonged at 62 seconds (reference range 23.0–32.4). The rest of her blood counts and her prothrombin time, liver enzyme levels, and serum creatinine level are normal.

Should this patient be tested for antiphospholipid antibodies?

Antiphospholipid antibodies are important because of their association with thrombotic risk (both venous and arterial) and pregnancy morbidity. The name is a misnomer, as these antibodies are targeted against some proteins that are bound to phospholipids and not only to the phospholipids themselves.

According to the modified Sapporo criteria for the classification of antiphospholipid syndrome,²⁸ antiphospholipid antibodies should remain persistently positive on at least 2 separate occasions at least 12 weeks apart for the result to be considered significant because some infections and drugs may be associated with the transient presence of antiphospholipid antibodies.

Screening for antiphospholipid antibodies should include testing for IgM and IgG anticardiolipin antibodies, lupus anticoagulant, and IgM and IgG beta-2 glycoprotein I antibodies.^29,30

Anticardiolipin antibodies

Anticardiolipin (aCL) antibodies may be targeted either against beta-2 glycoprotein I (beta-2GPI) that is bound to cardiolipin (a phospholipid) or against cardiolipin alone; the former is more specific. Antibodies directed against cardiolipin alone are usually transient and are associated with infections and drugs. The result is considered significant only when anticardiolipin antibodies are present in a medium to high titer (> 40 IgG phospholipid units or IgM phospholipid units, or > 99th percentile).

Lupus anticoagulant

The antibody with “lupus anticoagulant activity” is targeted against prothrombin plus phospholipid or beta-2GPI plus phospholipid. The test for it is a functional assay involving 3 steps:

Demonstrating the prolongation of a phospholipid-dependent coagulation assay like the activated partial thromboplastin time (aPTT). (This may explain the prolongation of aPTT in the patient described in the vignette.) Although the presence of lupus anticoagulant is associated with thrombosis, it is called an “anticoagulant” because of this in vitro prolongation of phospholipid-dependent coagulation assays.

Mixing study. The phospholipid-dependent coagulation assay could be prolonged because of either the deficiency of a coagulation factor or the presence of the antiphospholipid antibodies. This can be differentiated by mixing the patient’s plasma with normal plasma (which will have all the clotting factors) in a 1:1 ratio. If the coagulation assay remains prolonged after the addition of normal plasma, clotting factor deficiency can be excluded.

Addition of a phospholipid. If the prolongation of the coagulation assay is due to the presence of an antiphospholipid antibody, addition of extra phospholipid will correct this.

Beta-2 glycoprotein I antibody (anti-beta-2GPI)

The beta-2GPI that is not bound to the cardiolipin can be detected by separately testing for beta-2GPI (the anticardiolipin test only detects the beta-2GPI that is bound to the cardiolipin). The result is considered significant if beta-2GPI is present in a medium to high titer (> 99th percentile).

Studies have shown that antiphospholipid antibodies may be present in 1% to 5% of apparently healthy people in the general population.³¹ These are usually low-titer anticardiolipin or anti-beta-GPI IgM antibodies that are not associated with thrombosis or adverse pregnancy outcomes. Hence, the term antiphospholipid syndrome should be reserved for those who have had at least 1 episode of thrombosis or pregnancy morbidity and persistent antiphospholipid antibodies, and not those who have asymptomatic or transient antiphospholipid antibodies.

Triple positivity (positive anticardiolipin, lupus anticoagulant, and anti-beta-2GPI) seems to be associated with the highest risk of thrombosis, with a 10-year cumulative incidence of 37.1% (95% confidence interval [CI] 19.9–54.3) for a first thrombotic event,³² and 44.2% (95% CI 38.6–49.8) for recurrent thrombosis.³³

The association with thrombosis is stronger for lupus anticoagulant than with the other 2 antibodies, with different studies³⁴ finding an odds ratio ranging from 5 to 16. A positive lupus anticoagulant test with or without a moderate to high titer of anticardiolipin or anti-beta-2GPI IgM or IgG constitutes a high-risk profile, while a moderate to high titer of anticardiolipin or anti-beta-2GPI IgM or IgG constitutes a moderate-risk profile. A low titer of anticardiolipin or anti-beta-2GPI IgM or IgG constitutes a low-risk profile that may not be associated with thrombosis.³⁵

Antiphospholipid syndrome is important to recognize because of the need for long-term anticoagulation to prevent recurrence.³⁶ It may be primary, when it occurs on its own, or secondary, when it occurs in association with another autoimmune disease such as lupus.

Venous events in antiphospholipid syndrome most commonly manifest as lower-limb deep vein thrombosis or pulmonary embolism, while arterial events most commonly manifest as stroke or transient ischemic attack.³⁷ Obstetric manifestations may include not only miscarriage and stillbirth, but also preterm delivery, intrauterine growth retardation, and preeclampsia, all occurring due to placental insufficiency.

The frequency of antiphospholipid antibodies has been estimated as 13.5% in patients with stroke, 11% with myocardial infarction, 9.5% with deep vein thrombosis, and 6% for those with pregnancy morbidity.³⁸

Some noncriteria manifestations have also been recognized in antiphospholipid syndrome, such as thrombocytopenia, cardiac vegetations (Libman-Sachs endocarditis), livedo reticularis, and nephropathy.

Back to our patient

Our patient’s anticardiolipin IgG test is negative, while her lupus anticoagulant and beta-2GPI IgG are positive. She has no clinical or laboratory features suggesting lupus.

She is started on warfarin. After 3 months, the warfarin is interrupted for several days, and she is retested for all 3 antiphospholipid antibodies. Her beta-2GPI I IgG and lupus anticoagulant tests are again positive. Because of the persistent antiphospholipid antibody positivity and clinical history of deep vein thrombosis, her condition is diagnosed as primary antiphospholipid syndrome. She is advised to continue anticoagulant therapy indefinitely.

A 34-year-old man who is an injecting drug user presents with a 2-week history of fever, malaise, and generalized arthralgia. There are no localizing symptoms of infection. Notable findings on examination include a temperature of 38.0°C (100.4°F), needle track marks in his arms, nonblanching vasculitic rash in his legs, and a systolic murmur over the precordium.

His white blood cell count is 15.3 × 10⁹/L (reference range 3.7–11.0), and his C-reactive protein level is 234 mg/dL (normal < 3). Otherwise, results of blood cell counts, liver enzyme tests, renal function tests, urinalysis, and chest radiography are normal.

Two sets of blood cultures are drawn. Transthoracic echocardiography and the antineutrophil cytoplasmic antibody (ANCA) test are requested, as are screening tests for human immunodeficiency virus, hepatitis B, and hepatitis C.

Was the ANCA test indicated in this patient?

ANCAs are autoantibodies against antigens located in the cytoplasmic granules of neutrophils and monocytes. They are associated with small-vessel vasculitides such as granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), eosinophilic granulomatosis with polyangiitis (EGPA), and isolated pauciimmune crescentic glomerulonephritis, all collectively known as ANCA-associated vasculitis (AAV).³⁹

Laboratory methods to detect ANCA include indirect immunofluorescence and antigen-specific enzyme immunoassays. Indirect immunofluorescence only tells us whether or not an antibody that is targeting a cytoplasmic antigen is present. Based on the indirect immunofluorescent pattern, ANCA can be classified as follows:

• Perinuclear or p-ANCA (if the targeted antigen is located just around the nucleus and extends into it)
• Cytoplasmic or c-ANCA (if the targeted antigen is located farther away from the nucleus)
• Atypical ANCA (if the indirect immunofluorescent pattern does not fit with either p-ANCA or c-ANCA).

Indirect immunofluorescence does not give information about the exact antigen that is targeted; this can only be obtained by performing 1 of the antigen-specific immunoassays. The target antigen for c-ANCA is usually proteinase-3 (PR3), while that for p-ANCA could be myeloperoxidase (MPO), cathepsin, lysozyme, lactoferrin, or bactericidal permeability inhibitor. Anti-PR3 is highly specific for GPA, while anti-MPO is usually associated with MPA and EGPA. Less commonly, anti-PR3 may be seen in patients with MPA and anti-MPO in those with GPA. Hence, there is an increasing trend toward classifying ANCA-associated vasculitis into PR3-associated or MPO-associated vasculitis rather than as GPA, MPA, EGPA, or renal-limited vasculitis.⁴⁰

Several audits have shown that the ANCA test is widely misused and requested indiscriminately to rule out vasculitis. This results in a lower positive predictive value, possible harm to patients due to increased false-positive rates, and increased burden on the laboratory.^41–43 At least 2 separate groups have demonstrated that a gating policy that refuses ANCA testing in patients without clinical evidence of systemic vasculitis can reduce the number of inappropriate requests, improve the diagnostic yield, and make it more clinically relevant and cost-effective.^44,45

The clinician should bear in mind that:

Current guidelines recommend using one of the antigen-specific assays for PR3 and MPO as the primary screening method.⁴⁸ Until recently, indirect immunofluorescence was used to screen for ANCA-associated vasculitis, and positive results were confirmed by ELISA to detect ANCAs specific for PR3 and MPO,⁴⁹ but this is no longer recommended because of recent evidence suggesting a large variability between the different indirect immunofluorescent methods and improved diagnostic performance of the antigen-specific assays.

In a large multicenter study by Damoiseaux et al, the specificity with the different antigen-specific immunoassays was 98% to 99% for PR3-ANCA and 96% to 99% for MPO-ANCA.⁵⁰

ANCA-associated vasculitis should not be considered excluded if the PR3 and MPO-ANCA are negative. In the Damoiseaux study, about 11% to 15% of patients with GPA and 8% to 24% of patients with MPA tested negative for both PR3 and MPO-ANCA.⁵⁰

If the ANCA result is negative and clinical suspicion for ANCA-associated vasculitis is high, the clinician may wish to consider requesting another immunoassay method or indirect immunofluorescence. Results of indirect immunofluorescent testing results may be positive in those with a negative immunoassay, and vice versa.

Thus, the ANCA result should always be interpreted in the context of the whole clinical picture.⁵¹ Biopsy should still be considered the gold standard for the diagnosis of ANCA-associated vasculitis. The ANCA titer can help to improve clinical interpretation, because the likelihood of ANCA-associated vasculitis increases with higher levels of PR3 and MPO-ANCA.⁵²

Back to our patient

Our patient’s blood cultures grow methicillin-sensitive Staphylococcus aureus in both sets after 48 hours. Transthoracic echocardiography reveals vegetations around the tricuspid valve, with no evidence of valvular regurgitation. The diagnosis is right-sided infective endocarditis. He is started on appropriate antibiotics.

Tests for human immunodeficiency virus, hepatitis B, and hepatitis C are negative. The ANCA test is positive for MPO-ANCA at 28 IU/mL (normal < 10).

The positive ANCA is thought to be related to the infective endocarditis. His vasculitis is most likely secondary to infective endocarditis and not ANCA-associated vasculitis. The ANCA test need not have been requested in the first place.

A 22-year-old man presents to his primary care physician with a 4-month history of gradually worsening low back pain associated with early morning stiffness lasting more than 2 hours. He has no peripheral joint symptoms.

In the last 2 years, he has had 2 separate episodes of uveitis. There is a family history of ankylosing spondylitis in his father. Examination reveals global restriction of lumbar movements but is otherwise unremarkable. Magnetic resonance imaging (MRI) of the lumbar spine and sacroiliac joints is normal.

Should this patient be tested for human leukocyte antigen-B27 (HLA-B27)?

The major histocompatibility complex (MHC) is a gene complex that is present in all animals. It encodes proteins that help with immunologic tolerance. HLA simply refers to the human version of the MHC.⁵³ The HLA gene complex, located on chromosome 6, is categorized into class I, class II, and class III. HLA-B is one of the 3 class I genes. Thus, a positive HLA-B27 result simply means that the particular gene is present in that person.

HLA-B27 is strongly associated with ankylosing spondylitis, also known as axial spondyloarthropathy.⁵⁴ Other genes also contribute to the pathogenesis of ankylosing spondylitis, but HLA-B27 is present in more than 90% of patients with this disease and is by far considered the most important. The association is not as strong for peripheral spondyloarthropathy, with studies reporting a frequency of up to 75% for reactive arthritis and inflammatory bowel disease-associated arthritis, and up to 50% for psoriatic arthritis and uveitis.⁵⁵

About 9% of healthy, asymptomatic individuals may have HLA-B27, so the mere presence of this gene is not evidence of disease.⁵⁶ There may be up to a 20-fold increased risk of ankylosing spondylitis among those who are HLA-B27-positive.⁵⁷

Some HLA genes have many different alleles, each of which is given a number (explaining the number 27 that follows the B). Closely related alleles that differ from one another by only a few amino-acid substitutions are then categorized together, thus accounting for more than 100 subtypes of HLA-B27 (designated from HLA-B*2701 to HLA-B*27106). These subtypes vary in frequency among different racial groups, and the population prevalence of ankylosing spondylitis parallels the frequency of HLA-B27.⁵⁸ The most common subtype seen in white people and American Indians is B*2705. HLA-B27 is rare in blacks, explaining the rarity of ankylosing spondylitis in this population. Further examples include HLA-B*2704, which is seen in Asians, and HLA-B*2702, seen in Mediterranean populations. Not all subtypes of HLA-B27 are associated with disease, and some, like HLA-B*2706, may also be protective.

When should the clinician consider testing for HLA-B27?

Peripheral spondyloarthropathy may present with arthritis, enthesitis (eg, heel pain due to inflammation at the site of insertion of the Achilles tendon or plantar fascia), or dactylitis (“sausage” swelling of the whole finger or toe due to extension of inflammation beyond the margins of the joint). Other clues may include psoriasis, inflammatory bowel disease, history of preceding gastrointestinal or genitourinary infection, family history of similar conditions, and history of recurrent uveitis.

For the initial assessment of patients who have inflammatory back pain, plain radiography of the sacroiliac joints is considered the gold standard.⁵⁹ If plain radiography does not show evidence of sacroiliitis, MRI of the sacroiliac joints should be considered. While plain radiography can reveal only structural changes such as sclerosis, erosions, and ankylosis, MRI is useful to evaluate for early inflammatory changes such as bone marrow edema. Imaging the lumbar spine is not necessary, as the sacroiliac joints are almost invariably involved in axial spondyloarthropathy, and lesions seldom occur in the lumbar spine in isolation.⁶⁰

The diagnosis of ankylosing spondylitis previously relied on confirmatory imaging features, but based on the new International Society classification criteria,^61–63 which can be applied to patients with more than 3 months of back pain and age of onset of symptoms before age 45, patients can be classified as having 1 of the following:

• Radiographic axial spondyloarthropathy, if they have evidence of sacroiliitis on imaging plus 1 other feature of spondyloarthropathy
• Nonradiographic axial spondyloarthropathy, if they have a positive HLA-B27 plus 2 other features of spondyloarthropathy (Table 7).

These new criteria have a sensitivity of 82.9% and specificity of 84.4%.^62,63 The disease burden of radiographic and nonradiographic axial spondyloarthropathy has been shown to be similar, suggesting that they are part of the same disease spectrum. Thus, the HLA-B27 test is useful to make a diagnosis of axial spondyloarthropathy even in the absence of imaging features and could be requested in patients with 2 or more features of spondyloarthropathy. In the absence of imaging features and a negative HLA-B27 result, however, the patient cannot be classified as having axial spondyloarthropathy.

Back to our patient

The absence of radiographic evidence would not exclude axial spondyloarthropathy in our patient. The HLA-B27 test is requested because of the inflammatory back pain and the presence of 2 spondyloarthropathy features (uveitis and the family history) and is reported to be positive. His disease is classified as nonradiographic axial spondyloarthropathy.

He is started on regular naproxen and is referred to a physiotherapist. After 1 month, he reports significant symptomatic improvement. He asks if he can be retested for HLA-B27 to see if it has become negative. We tell him that there is no point in repeating it, as it is a gene and will not disappear.

SUMMARY: CONSIDER THE CLINICAL PICTURE

When approaching a patient suspected of having a rheumatologic disease, a clinician should first consider the clinical presentation and the intended purpose of each test. The tests, in general, might serve several purposes. They might help to:

Increase the likelihood of the diagnosis in question. For example, a positive rheumatoid factor or anticitrullinated peptide antibody can help diagnose rheumatoid arthritis in a patient with early polyarthritis, a positive HLA-B27 can help diagnose ankylosing spondylitis in patients with inflammatory back pain and normal imaging, and a positive ANCA can help diagnose ANCA-associated vasculitis in a patient with glomerulonephritis.

Reduce the likelihood of the diagnosis in question. For example, a negative antinuclear antibody test reduces the likelihood of lupus in a patient with joint pains.

Monitor the condition. For example DNA antibodies can be used to monitor the activity of lupus.

Plan the treatment strategy. For example, one might consider lifelong anticoagulation if antiphospholipid antibodies are persistently positive in a patient with thrombosis.

Prognosticate. For example, positive rheumatoid factor and anticitrullinated peptide antibody increase the risk of erosive rheumatoid arthritis.

If the test was requested in the absence of a clear indication and the result is positive, it is important to bear in mind the potential pitfalls associated with that test and not attach a diagnostic label prematurely. None of the tests can confirm or exclude a condition, so the results should always be interpreted in the context of the whole clinical picture.   

Laboratory tests are often ordered inappropriately for patients in whom a rheumatologic illness is suspected; this occurs in both primary and secondary care.¹ Some tests are available both singly and as part of a battery of tests screening healthy people without symptoms.

The problem: negative test results are by no means always reassuring, and false-positive results raise the risks of unnecessary anxiety for patients and clinicians, needless referrals, and potential morbidity due to further unnecessary testing and exposure to wrong treatments.² Clinicians should be aware of the pitfalls of these tests in order to choose them wisely and interpret the results correctly.

This article provides practical guidance on requesting and interpreting some common tests in rheumatology, with the aid of case vignettes.

RHEUMATOID FACTOR AND ANTICITRULLINATED PEPTIDE ANTIBODY

A 41-year-old woman, previously in good health, presents to her primary care practitioner with a 6-week history of pain and swelling in her hands and early morning stiffness lasting about 2 hours. She denies having any extraarticular symptoms. Physical examination reveals synovitis across her right metacarpophalangeal joints, proximal interphalangeal joint of the left middle finger, and left wrist. The primary care physician is concerned that her symptoms might be due to rheumatoid arthritis.

Would testing for rheumatoid factor and anticitrullinated peptide antibody be useful in this patient?

Rheumatoid factor is an antibody (immunoglobulin M, IgG, or IgA) targeted against the Fc fragment of IgG.³ It was so named because it was originally detected in patients with rheumatoid arthritis, but it is neither sensitive nor specific for this condition. A meta-analysis of more than 5,000 patients with rheumatoid arthritis reported that rheumatoid factor testing had a sensitivity of 69% and specificity of 85%.⁴

Anticitrullinated peptide antibody, on the other hand, is much more specific for rheumatoid arthritis (95%), as it is seldom seen in other conditions, but its sensitivity is similar to that of rheumatoid factor (68%).^4–6 A positive result would thus lend strength to the diagnosis of rheumatoid arthritis, but a negative result would not exclude it.

Approach to early arthritis

When faced with a patient with early arthritis, some key questions to ask include^7,8:

Is this an inflammatory or a mechanical problem? Inflammatory arthritis is suggested by joint swelling that is not due to trauma or bony hypertrophy, early morning stiffness lasting longer than 30 minutes, and elevated inflammatory markers (erythrocyte sedimentation rate or C-reactive protein). Involvement of the small joints of the hands and feet may be suggested by pain on compression of the metacarpophalangeal and metatarsophalangeal joints, respectively.

Is there a definite identifiable underlying cause for the inflammatory arthritis? The pattern of development of joint symptoms or the presence of extraarticular symptoms may suggest an underlying problem such as gout, psoriatic arthritis, systemic lupus erythematosus, or sarcoidosis.

If the arthritis is undifferentiated (ie, there is no definite identifiable cause), is it likely to remit or persist? This is perhaps the most important question to ask in order to prognosticate. Patients with risk factors for persistent disease, ie, for development of rheumatoid arthritis, should be referred to a rheumatologist early for timely institution of disease-modifying antirheumatic drug therapy.⁹ Multiple studies have shown that patients in whom this therapy is started early have much better clinical, functional, and radiologic outcomes than those in whom it is delayed.^10–12

The revised American College of Rheumatology and European League Against Rheumatism criteria¹³ include the following factors as predictors of persistence:

• Number of involved joints (with greater weight given to involvement of small joints)
• Duration of symptoms 6 weeks or longer
• Elevated acute-phase response (erythrocyte sedimentation rate or C-reactive protein level)
• A positive serologic test (either rheumatoid factor or anticitrullinated peptide antibody).

If both rheumatoid factor and anticitrullinated peptide antibody are positive in a patient with early undifferentiated arthritis, the risk of progression to rheumatoid arthritis is almost 100%, thus underscoring the importance of testing for these antibodies.^5,6 Referral to a rheumatologist should, however, not be delayed in patients with negative test results (more than one-third of patients with rheumatoid arthritis may be negative for both), and should be considered in those with inflammatory joint symptoms persisting longer than 6 weeks, especially with involvement of the small joints (sparing the distal interphalangeals) and elevated acute-phase response.

Rheumatoid factor in healthy people without symptoms

In some countries, testing for rheumatoid factor is offered as part of a battery of screening tests in healthy people who have no symptoms, a practice that should be strongly discouraged.

Multiple studies, both prospective and retrospective, have demonstrated that both rheumatoid factor and anticitrullinated peptide antibody may be present several years before the clinical diagnosis of rheumatoid arthritis.^6,14–16 But the risk of developing rheumatoid arthritis for asymptomatic individuals who are rheumatoid factor-positive depends on the rheumatoid factor titer, positive family history of rheumatoid arthritis in first-degree relatives, and copresence of anticitrullinated peptide antibody. The absolute risk, nevertheless, is still very small. In some, there might be an alternative explanation such as undiagnosed Sjögren syndrome or hepatitis C.

In any event, no strategy is currently available that is proven to prevent the development of rheumatoid arthritis, and there is no role for disease-modifying therapy during the preclinical phase.¹⁶

Back to our patient

Blood testing in our patient reveals normal complete blood cell counts, aminotransferase levels, and serum creatinine concentration; findings on urinalysis are normal. Her erythrocyte sedimentation rate is 56 mm/hour (reference range 0–15), and her C-reactive protein level is 26 mg/dL (normal < 3). Testing is negative for rheumatoid factor and anticitrullinated peptide antibody.

Although her rheumatoid factor and anticitrullinated peptide antibody tests are negative, she is referred to a rheumatologist because she has predictors of persistent disease, ie, symptom duration of 6 weeks, involvement of the small joints of the hands, and elevated erythrocyte sedimentation rate and C-reactive protein. The rheumatologist checks her parvovirus serology, which is negative.

The patient is given parenteral depot corticosteroid therapy, to which she responds briefly. Because her symptoms persist and continue to worsen, methotrexate treatment is started after an additional 6 weeks.

A 37-year-old woman presents to her primary care physician with the complaint of tiredness. She has a family history of systemic lupus erythematosus in her sister and maternal aunt. She is understandably worried about lupus because of the family history and is asking to be tested for it.

Would testing for antinuclear antibody be reasonable?

Antinuclear antibody is not a single antibody but rather a family of autoantibodies that are directed against nuclear constituents such as single- or double-stranded deoxyribonucleic acid (dsDNA), histones, centromeres, proteins complexed with ribonucleic acid (RNA), and enzymes such as topoisomerase.^17,18

Protein antigens complexed with RNA and some enzymes in the nucleus are also known as extractable nuclear antigens (ENAs). They include Ro, La, Sm, Jo-1, RNP, and ScL-70 and are named after the patient in whom they were first discovered (Robert, Lavine, Smith, and John), the antigen that is targeted (ribonucleoprotein or RNP), and the disease with which they are associated (anti-ScL-70 or antitopoisomerase in diffuse cutaneous scleroderma).

Antinuclear antibody testing is commonly requested to exclude connective tissue diseases such as lupus, but the clinician needs to be aware of the following points:

Antinuclear antibody may be encountered in conditions other than lupus

These include¹⁹:

• Other autoimmune diseases such as rheumatoid arthritis, primary Sjögren syndrome, systemic sclerosis, autoimmune thyroid disease, and myasthenia gravis
• Infection with organisms that share the epitope with self-antigens (molecular mimicry)
• Cancers
• Drugs such as hydralazine, procainamide, and minocycline.

Antinuclear antibody might also be produced by the healthy immune system from time to time to clear the nuclear debris that is extruded from aging cells.

A study in healthy individuals²⁰ reported a prevalence of positive antinuclear antibody of 32% at a titer of 1/40, 15% at a titer of 1/80, 7% at a titer of 1/160, and 3% at a titer of 1/320. Importantly, a positive result was more common among family members of patients with autoimmune connective tissue diseases.²¹ Hence, a positive antinuclear antibody result does not always mean lupus.

Antinuclear antibody testing is highly sensitive for lupus

With current laboratory methods, antinuclear antibody testing has a sensitivity close to 100%. Hence, a negative result virtually rules out lupus.

Two methods are commonly used to test for antinuclear antibody: indirect immunofluorescence and enzyme-linked immunosorbent assay (ELISA).²² While human epithelial (Hep2) cells are used as the source of antigen in immunofluorescence, purified nuclear antigens coated on multiple-well plates are used in ELISA.

Although ELISA is simpler to perform, immunofluorescence has a slightly better sensitivity (because the Hep2 cells express a wide range of antigens) and is still considered the gold standard. As expected, the higher sensitivity occurs at the cost of reduced specificity (about 60%), so antinuclear antibody will also be detected in all the other conditions listed above.²³

To improve the specificity of antinuclear antibody testing, laboratories report titers (the highest dilution of the test serum that tested positive); a cutoff of greater than 1/80 is generally considered significant.

Do not order antinuclear antibody testing indiscriminately

To sum up, the antinuclear antibody test should be requested only in patients with involvement of multiple organ systems. Although a negative result would make it extremely unlikely that the clinical presentation is due to lupus, a positive result is insufficient on its own to make a diagnosis of lupus.

Diagnosing lupus is straightforward when patients present with a specific manifestation such as inflammatory arthritis, photosensitive skin rash, hemolytic anemia, thrombocytopenia, or nephritis, or with specific antibodies such as those against dsDNA or Sm. Patients who present with nonspecific symptoms such as arthralgia or tiredness with a positive antinuclear antibody and negative anti-dsDNA and anti-Sm may present difficulties even for the specialist.^25–27

Back to our patient

Our patient denies arthralgia. She has no extraarticular symptoms such as skin rashes, oral ulcers, sicca symptoms, muscle weakness, Raynaud phenomenon, pleuritic chest pain, or breathlessness. Findings on physical examination and urinalysis are unremarkable.

Her primary care physician decides to check her complete blood cell count, erythrocyte sedimentation rate, and thyroid-stimulating hormone level. Although she is reassured that her tiredness is not due to lupus, she insists on getting an antinuclear antibody test.

Her complete blood cell counts are normal. Her erythrocyte sedimentation rate is 6 mm/hour. However, her thyroid-stimulating hormone level is elevated, and subsequent testing shows low free thyroxine and positive thyroid peroxidase antibodies. The antinuclear antibody is positive in a titer of 1/80 and negative for anti-dsDNA and anti-ENA.

We explain to her that the positive antinuclear antibody is most likely related to her autoimmune thyroid disease. She is referred to an endocrinologist.

A 24-year-old woman presents to the emergency department with acute unprovoked deep vein thrombosis in her right leg, confirmed by ultrasonography. She has no history of previous thrombosis, and the relevant family history is unremarkable. She has never been pregnant. Her platelet count is 84 × 10⁹/L (reference range 150–400), and her baseline activated partial thromboplastin time is prolonged at 62 seconds (reference range 23.0–32.4). The rest of her blood counts and her prothrombin time, liver enzyme levels, and serum creatinine level are normal.

Should this patient be tested for antiphospholipid antibodies?

Antiphospholipid antibodies are important because of their association with thrombotic risk (both venous and arterial) and pregnancy morbidity. The name is a misnomer, as these antibodies are targeted against some proteins that are bound to phospholipids and not only to the phospholipids themselves.

According to the modified Sapporo criteria for the classification of antiphospholipid syndrome,²⁸ antiphospholipid antibodies should remain persistently positive on at least 2 separate occasions at least 12 weeks apart for the result to be considered significant because some infections and drugs may be associated with the transient presence of antiphospholipid antibodies.

Screening for antiphospholipid antibodies should include testing for IgM and IgG anticardiolipin antibodies, lupus anticoagulant, and IgM and IgG beta-2 glycoprotein I antibodies.^29,30

Anticardiolipin antibodies

Anticardiolipin (aCL) antibodies may be targeted either against beta-2 glycoprotein I (beta-2GPI) that is bound to cardiolipin (a phospholipid) or against cardiolipin alone; the former is more specific. Antibodies directed against cardiolipin alone are usually transient and are associated with infections and drugs. The result is considered significant only when anticardiolipin antibodies are present in a medium to high titer (> 40 IgG phospholipid units or IgM phospholipid units, or > 99th percentile).

Lupus anticoagulant

The antibody with “lupus anticoagulant activity” is targeted against prothrombin plus phospholipid or beta-2GPI plus phospholipid. The test for it is a functional assay involving 3 steps:

Demonstrating the prolongation of a phospholipid-dependent coagulation assay like the activated partial thromboplastin time (aPTT). (This may explain the prolongation of aPTT in the patient described in the vignette.) Although the presence of lupus anticoagulant is associated with thrombosis, it is called an “anticoagulant” because of this in vitro prolongation of phospholipid-dependent coagulation assays.

Mixing study. The phospholipid-dependent coagulation assay could be prolonged because of either the deficiency of a coagulation factor or the presence of the antiphospholipid antibodies. This can be differentiated by mixing the patient’s plasma with normal plasma (which will have all the clotting factors) in a 1:1 ratio. If the coagulation assay remains prolonged after the addition of normal plasma, clotting factor deficiency can be excluded.

Addition of a phospholipid. If the prolongation of the coagulation assay is due to the presence of an antiphospholipid antibody, addition of extra phospholipid will correct this.

Beta-2 glycoprotein I antibody (anti-beta-2GPI)

The beta-2GPI that is not bound to the cardiolipin can be detected by separately testing for beta-2GPI (the anticardiolipin test only detects the beta-2GPI that is bound to the cardiolipin). The result is considered significant if beta-2GPI is present in a medium to high titer (> 99th percentile).

Studies have shown that antiphospholipid antibodies may be present in 1% to 5% of apparently healthy people in the general population.³¹ These are usually low-titer anticardiolipin or anti-beta-GPI IgM antibodies that are not associated with thrombosis or adverse pregnancy outcomes. Hence, the term antiphospholipid syndrome should be reserved for those who have had at least 1 episode of thrombosis or pregnancy morbidity and persistent antiphospholipid antibodies, and not those who have asymptomatic or transient antiphospholipid antibodies.

Triple positivity (positive anticardiolipin, lupus anticoagulant, and anti-beta-2GPI) seems to be associated with the highest risk of thrombosis, with a 10-year cumulative incidence of 37.1% (95% confidence interval [CI] 19.9–54.3) for a first thrombotic event,³² and 44.2% (95% CI 38.6–49.8) for recurrent thrombosis.³³

The association with thrombosis is stronger for lupus anticoagulant than with the other 2 antibodies, with different studies³⁴ finding an odds ratio ranging from 5 to 16. A positive lupus anticoagulant test with or without a moderate to high titer of anticardiolipin or anti-beta-2GPI IgM or IgG constitutes a high-risk profile, while a moderate to high titer of anticardiolipin or anti-beta-2GPI IgM or IgG constitutes a moderate-risk profile. A low titer of anticardiolipin or anti-beta-2GPI IgM or IgG constitutes a low-risk profile that may not be associated with thrombosis.³⁵

Antiphospholipid syndrome is important to recognize because of the need for long-term anticoagulation to prevent recurrence.³⁶ It may be primary, when it occurs on its own, or secondary, when it occurs in association with another autoimmune disease such as lupus.

Venous events in antiphospholipid syndrome most commonly manifest as lower-limb deep vein thrombosis or pulmonary embolism, while arterial events most commonly manifest as stroke or transient ischemic attack.³⁷ Obstetric manifestations may include not only miscarriage and stillbirth, but also preterm delivery, intrauterine growth retardation, and preeclampsia, all occurring due to placental insufficiency.

The frequency of antiphospholipid antibodies has been estimated as 13.5% in patients with stroke, 11% with myocardial infarction, 9.5% with deep vein thrombosis, and 6% for those with pregnancy morbidity.³⁸

Some noncriteria manifestations have also been recognized in antiphospholipid syndrome, such as thrombocytopenia, cardiac vegetations (Libman-Sachs endocarditis), livedo reticularis, and nephropathy.

Back to our patient

Our patient’s anticardiolipin IgG test is negative, while her lupus anticoagulant and beta-2GPI IgG are positive. She has no clinical or laboratory features suggesting lupus.

She is started on warfarin. After 3 months, the warfarin is interrupted for several days, and she is retested for all 3 antiphospholipid antibodies. Her beta-2GPI I IgG and lupus anticoagulant tests are again positive. Because of the persistent antiphospholipid antibody positivity and clinical history of deep vein thrombosis, her condition is diagnosed as primary antiphospholipid syndrome. She is advised to continue anticoagulant therapy indefinitely.

A 34-year-old man who is an injecting drug user presents with a 2-week history of fever, malaise, and generalized arthralgia. There are no localizing symptoms of infection. Notable findings on examination include a temperature of 38.0°C (100.4°F), needle track marks in his arms, nonblanching vasculitic rash in his legs, and a systolic murmur over the precordium.

His white blood cell count is 15.3 × 10⁹/L (reference range 3.7–11.0), and his C-reactive protein level is 234 mg/dL (normal < 3). Otherwise, results of blood cell counts, liver enzyme tests, renal function tests, urinalysis, and chest radiography are normal.

Two sets of blood cultures are drawn. Transthoracic echocardiography and the antineutrophil cytoplasmic antibody (ANCA) test are requested, as are screening tests for human immunodeficiency virus, hepatitis B, and hepatitis C.

Was the ANCA test indicated in this patient?

ANCAs are autoantibodies against antigens located in the cytoplasmic granules of neutrophils and monocytes. They are associated with small-vessel vasculitides such as granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), eosinophilic granulomatosis with polyangiitis (EGPA), and isolated pauciimmune crescentic glomerulonephritis, all collectively known as ANCA-associated vasculitis (AAV).³⁹

Laboratory methods to detect ANCA include indirect immunofluorescence and antigen-specific enzyme immunoassays. Indirect immunofluorescence only tells us whether or not an antibody that is targeting a cytoplasmic antigen is present. Based on the indirect immunofluorescent pattern, ANCA can be classified as follows:

• Perinuclear or p-ANCA (if the targeted antigen is located just around the nucleus and extends into it)
• Cytoplasmic or c-ANCA (if the targeted antigen is located farther away from the nucleus)
• Atypical ANCA (if the indirect immunofluorescent pattern does not fit with either p-ANCA or c-ANCA).

Indirect immunofluorescence does not give information about the exact antigen that is targeted; this can only be obtained by performing 1 of the antigen-specific immunoassays. The target antigen for c-ANCA is usually proteinase-3 (PR3), while that for p-ANCA could be myeloperoxidase (MPO), cathepsin, lysozyme, lactoferrin, or bactericidal permeability inhibitor. Anti-PR3 is highly specific for GPA, while anti-MPO is usually associated with MPA and EGPA. Less commonly, anti-PR3 may be seen in patients with MPA and anti-MPO in those with GPA. Hence, there is an increasing trend toward classifying ANCA-associated vasculitis into PR3-associated or MPO-associated vasculitis rather than as GPA, MPA, EGPA, or renal-limited vasculitis.⁴⁰

Several audits have shown that the ANCA test is widely misused and requested indiscriminately to rule out vasculitis. This results in a lower positive predictive value, possible harm to patients due to increased false-positive rates, and increased burden on the laboratory.^41–43 At least 2 separate groups have demonstrated that a gating policy that refuses ANCA testing in patients without clinical evidence of systemic vasculitis can reduce the number of inappropriate requests, improve the diagnostic yield, and make it more clinically relevant and cost-effective.^44,45

The clinician should bear in mind that:

Current guidelines recommend using one of the antigen-specific assays for PR3 and MPO as the primary screening method.⁴⁸ Until recently, indirect immunofluorescence was used to screen for ANCA-associated vasculitis, and positive results were confirmed by ELISA to detect ANCAs specific for PR3 and MPO,⁴⁹ but this is no longer recommended because of recent evidence suggesting a large variability between the different indirect immunofluorescent methods and improved diagnostic performance of the antigen-specific assays.

In a large multicenter study by Damoiseaux et al, the specificity with the different antigen-specific immunoassays was 98% to 99% for PR3-ANCA and 96% to 99% for MPO-ANCA.⁵⁰

ANCA-associated vasculitis should not be considered excluded if the PR3 and MPO-ANCA are negative. In the Damoiseaux study, about 11% to 15% of patients with GPA and 8% to 24% of patients with MPA tested negative for both PR3 and MPO-ANCA.⁵⁰

If the ANCA result is negative and clinical suspicion for ANCA-associated vasculitis is high, the clinician may wish to consider requesting another immunoassay method or indirect immunofluorescence. Results of indirect immunofluorescent testing results may be positive in those with a negative immunoassay, and vice versa.

Thus, the ANCA result should always be interpreted in the context of the whole clinical picture.⁵¹ Biopsy should still be considered the gold standard for the diagnosis of ANCA-associated vasculitis. The ANCA titer can help to improve clinical interpretation, because the likelihood of ANCA-associated vasculitis increases with higher levels of PR3 and MPO-ANCA.⁵²

Back to our patient

Our patient’s blood cultures grow methicillin-sensitive Staphylococcus aureus in both sets after 48 hours. Transthoracic echocardiography reveals vegetations around the tricuspid valve, with no evidence of valvular regurgitation. The diagnosis is right-sided infective endocarditis. He is started on appropriate antibiotics.

Tests for human immunodeficiency virus, hepatitis B, and hepatitis C are negative. The ANCA test is positive for MPO-ANCA at 28 IU/mL (normal < 10).

The positive ANCA is thought to be related to the infective endocarditis. His vasculitis is most likely secondary to infective endocarditis and not ANCA-associated vasculitis. The ANCA test need not have been requested in the first place.

A 22-year-old man presents to his primary care physician with a 4-month history of gradually worsening low back pain associated with early morning stiffness lasting more than 2 hours. He has no peripheral joint symptoms.

In the last 2 years, he has had 2 separate episodes of uveitis. There is a family history of ankylosing spondylitis in his father. Examination reveals global restriction of lumbar movements but is otherwise unremarkable. Magnetic resonance imaging (MRI) of the lumbar spine and sacroiliac joints is normal.

Should this patient be tested for human leukocyte antigen-B27 (HLA-B27)?

The major histocompatibility complex (MHC) is a gene complex that is present in all animals. It encodes proteins that help with immunologic tolerance. HLA simply refers to the human version of the MHC.⁵³ The HLA gene complex, located on chromosome 6, is categorized into class I, class II, and class III. HLA-B is one of the 3 class I genes. Thus, a positive HLA-B27 result simply means that the particular gene is present in that person.

HLA-B27 is strongly associated with ankylosing spondylitis, also known as axial spondyloarthropathy.⁵⁴ Other genes also contribute to the pathogenesis of ankylosing spondylitis, but HLA-B27 is present in more than 90% of patients with this disease and is by far considered the most important. The association is not as strong for peripheral spondyloarthropathy, with studies reporting a frequency of up to 75% for reactive arthritis and inflammatory bowel disease-associated arthritis, and up to 50% for psoriatic arthritis and uveitis.⁵⁵

About 9% of healthy, asymptomatic individuals may have HLA-B27, so the mere presence of this gene is not evidence of disease.⁵⁶ There may be up to a 20-fold increased risk of ankylosing spondylitis among those who are HLA-B27-positive.⁵⁷

Some HLA genes have many different alleles, each of which is given a number (explaining the number 27 that follows the B). Closely related alleles that differ from one another by only a few amino-acid substitutions are then categorized together, thus accounting for more than 100 subtypes of HLA-B27 (designated from HLA-B*2701 to HLA-B*27106). These subtypes vary in frequency among different racial groups, and the population prevalence of ankylosing spondylitis parallels the frequency of HLA-B27.⁵⁸ The most common subtype seen in white people and American Indians is B*2705. HLA-B27 is rare in blacks, explaining the rarity of ankylosing spondylitis in this population. Further examples include HLA-B*2704, which is seen in Asians, and HLA-B*2702, seen in Mediterranean populations. Not all subtypes of HLA-B27 are associated with disease, and some, like HLA-B*2706, may also be protective.

When should the clinician consider testing for HLA-B27?

Peripheral spondyloarthropathy may present with arthritis, enthesitis (eg, heel pain due to inflammation at the site of insertion of the Achilles tendon or plantar fascia), or dactylitis (“sausage” swelling of the whole finger or toe due to extension of inflammation beyond the margins of the joint). Other clues may include psoriasis, inflammatory bowel disease, history of preceding gastrointestinal or genitourinary infection, family history of similar conditions, and history of recurrent uveitis.

For the initial assessment of patients who have inflammatory back pain, plain radiography of the sacroiliac joints is considered the gold standard.⁵⁹ If plain radiography does not show evidence of sacroiliitis, MRI of the sacroiliac joints should be considered. While plain radiography can reveal only structural changes such as sclerosis, erosions, and ankylosis, MRI is useful to evaluate for early inflammatory changes such as bone marrow edema. Imaging the lumbar spine is not necessary, as the sacroiliac joints are almost invariably involved in axial spondyloarthropathy, and lesions seldom occur in the lumbar spine in isolation.⁶⁰

The diagnosis of ankylosing spondylitis previously relied on confirmatory imaging features, but based on the new International Society classification criteria,^61–63 which can be applied to patients with more than 3 months of back pain and age of onset of symptoms before age 45, patients can be classified as having 1 of the following:

• Radiographic axial spondyloarthropathy, if they have evidence of sacroiliitis on imaging plus 1 other feature of spondyloarthropathy
• Nonradiographic axial spondyloarthropathy, if they have a positive HLA-B27 plus 2 other features of spondyloarthropathy (Table 7).

These new criteria have a sensitivity of 82.9% and specificity of 84.4%.^62,63 The disease burden of radiographic and nonradiographic axial spondyloarthropathy has been shown to be similar, suggesting that they are part of the same disease spectrum. Thus, the HLA-B27 test is useful to make a diagnosis of axial spondyloarthropathy even in the absence of imaging features and could be requested in patients with 2 or more features of spondyloarthropathy. In the absence of imaging features and a negative HLA-B27 result, however, the patient cannot be classified as having axial spondyloarthropathy.

Back to our patient

The absence of radiographic evidence would not exclude axial spondyloarthropathy in our patient. The HLA-B27 test is requested because of the inflammatory back pain and the presence of 2 spondyloarthropathy features (uveitis and the family history) and is reported to be positive. His disease is classified as nonradiographic axial spondyloarthropathy.

He is started on regular naproxen and is referred to a physiotherapist. After 1 month, he reports significant symptomatic improvement. He asks if he can be retested for HLA-B27 to see if it has become negative. We tell him that there is no point in repeating it, as it is a gene and will not disappear.

SUMMARY: CONSIDER THE CLINICAL PICTURE

When approaching a patient suspected of having a rheumatologic disease, a clinician should first consider the clinical presentation and the intended purpose of each test. The tests, in general, might serve several purposes. They might help to:

Increase the likelihood of the diagnosis in question. For example, a positive rheumatoid factor or anticitrullinated peptide antibody can help diagnose rheumatoid arthritis in a patient with early polyarthritis, a positive HLA-B27 can help diagnose ankylosing spondylitis in patients with inflammatory back pain and normal imaging, and a positive ANCA can help diagnose ANCA-associated vasculitis in a patient with glomerulonephritis.

Reduce the likelihood of the diagnosis in question. For example, a negative antinuclear antibody test reduces the likelihood of lupus in a patient with joint pains.

Monitor the condition. For example DNA antibodies can be used to monitor the activity of lupus.

Plan the treatment strategy. For example, one might consider lifelong anticoagulation if antiphospholipid antibodies are persistently positive in a patient with thrombosis.

Prognosticate. For example, positive rheumatoid factor and anticitrullinated peptide antibody increase the risk of erosive rheumatoid arthritis.

If the test was requested in the absence of a clear indication and the result is positive, it is important to bear in mind the potential pitfalls associated with that test and not attach a diagnostic label prematurely. None of the tests can confirm or exclude a condition, so the results should always be interpreted in the context of the whole clinical picture.   

Laboratory tests are often ordered inappropriately for patients in whom a rheumatologic illness is suspected; this occurs in both primary and secondary care.¹ Some tests are available both singly and as part of a battery of tests screening healthy people without symptoms.

The problem: negative test results are by no means always reassuring, and false-positive results raise the risks of unnecessary anxiety for patients and clinicians, needless referrals, and potential morbidity due to further unnecessary testing and exposure to wrong treatments.² Clinicians should be aware of the pitfalls of these tests in order to choose them wisely and interpret the results correctly.

This article provides practical guidance on requesting and interpreting some common tests in rheumatology, with the aid of case vignettes.

RHEUMATOID FACTOR AND ANTICITRULLINATED PEPTIDE ANTIBODY

A 41-year-old woman, previously in good health, presents to her primary care practitioner with a 6-week history of pain and swelling in her hands and early morning stiffness lasting about 2 hours. She denies having any extraarticular symptoms. Physical examination reveals synovitis across her right metacarpophalangeal joints, proximal interphalangeal joint of the left middle finger, and left wrist. The primary care physician is concerned that her symptoms might be due to rheumatoid arthritis.

Would testing for rheumatoid factor and anticitrullinated peptide antibody be useful in this patient?

Rheumatoid factor is an antibody (immunoglobulin M, IgG, or IgA) targeted against the Fc fragment of IgG.³ It was so named because it was originally detected in patients with rheumatoid arthritis, but it is neither sensitive nor specific for this condition. A meta-analysis of more than 5,000 patients with rheumatoid arthritis reported that rheumatoid factor testing had a sensitivity of 69% and specificity of 85%.⁴

Anticitrullinated peptide antibody, on the other hand, is much more specific for rheumatoid arthritis (95%), as it is seldom seen in other conditions, but its sensitivity is similar to that of rheumatoid factor (68%).^4–6 A positive result would thus lend strength to the diagnosis of rheumatoid arthritis, but a negative result would not exclude it.

Approach to early arthritis

When faced with a patient with early arthritis, some key questions to ask include^7,8:

Is this an inflammatory or a mechanical problem? Inflammatory arthritis is suggested by joint swelling that is not due to trauma or bony hypertrophy, early morning stiffness lasting longer than 30 minutes, and elevated inflammatory markers (erythrocyte sedimentation rate or C-reactive protein). Involvement of the small joints of the hands and feet may be suggested by pain on compression of the metacarpophalangeal and metatarsophalangeal joints, respectively.

Is there a definite identifiable underlying cause for the inflammatory arthritis? The pattern of development of joint symptoms or the presence of extraarticular symptoms may suggest an underlying problem such as gout, psoriatic arthritis, systemic lupus erythematosus, or sarcoidosis.

If the arthritis is undifferentiated (ie, there is no definite identifiable cause), is it likely to remit or persist? This is perhaps the most important question to ask in order to prognosticate. Patients with risk factors for persistent disease, ie, for development of rheumatoid arthritis, should be referred to a rheumatologist early for timely institution of disease-modifying antirheumatic drug therapy.⁹ Multiple studies have shown that patients in whom this therapy is started early have much better clinical, functional, and radiologic outcomes than those in whom it is delayed.^10–12

The revised American College of Rheumatology and European League Against Rheumatism criteria¹³ include the following factors as predictors of persistence:

• Number of involved joints (with greater weight given to involvement of small joints)
• Duration of symptoms 6 weeks or longer
• Elevated acute-phase response (erythrocyte sedimentation rate or C-reactive protein level)
• A positive serologic test (either rheumatoid factor or anticitrullinated peptide antibody).

If both rheumatoid factor and anticitrullinated peptide antibody are positive in a patient with early undifferentiated arthritis, the risk of progression to rheumatoid arthritis is almost 100%, thus underscoring the importance of testing for these antibodies.^5,6 Referral to a rheumatologist should, however, not be delayed in patients with negative test results (more than one-third of patients with rheumatoid arthritis may be negative for both), and should be considered in those with inflammatory joint symptoms persisting longer than 6 weeks, especially with involvement of the small joints (sparing the distal interphalangeals) and elevated acute-phase response.

Rheumatoid factor in healthy people without symptoms

In some countries, testing for rheumatoid factor is offered as part of a battery of screening tests in healthy people who have no symptoms, a practice that should be strongly discouraged.

Multiple studies, both prospective and retrospective, have demonstrated that both rheumatoid factor and anticitrullinated peptide antibody may be present several years before the clinical diagnosis of rheumatoid arthritis.^6,14–16 But the risk of developing rheumatoid arthritis for asymptomatic individuals who are rheumatoid factor-positive depends on the rheumatoid factor titer, positive family history of rheumatoid arthritis in first-degree relatives, and copresence of anticitrullinated peptide antibody. The absolute risk, nevertheless, is still very small. In some, there might be an alternative explanation such as undiagnosed Sjögren syndrome or hepatitis C.

In any event, no strategy is currently available that is proven to prevent the development of rheumatoid arthritis, and there is no role for disease-modifying therapy during the preclinical phase.¹⁶

Back to our patient

Blood testing in our patient reveals normal complete blood cell counts, aminotransferase levels, and serum creatinine concentration; findings on urinalysis are normal. Her erythrocyte sedimentation rate is 56 mm/hour (reference range 0–15), and her C-reactive protein level is 26 mg/dL (normal < 3). Testing is negative for rheumatoid factor and anticitrullinated peptide antibody.

Although her rheumatoid factor and anticitrullinated peptide antibody tests are negative, she is referred to a rheumatologist because she has predictors of persistent disease, ie, symptom duration of 6 weeks, involvement of the small joints of the hands, and elevated erythrocyte sedimentation rate and C-reactive protein. The rheumatologist checks her parvovirus serology, which is negative.

The patient is given parenteral depot corticosteroid therapy, to which she responds briefly. Because her symptoms persist and continue to worsen, methotrexate treatment is started after an additional 6 weeks.

A 37-year-old woman presents to her primary care physician with the complaint of tiredness. She has a family history of systemic lupus erythematosus in her sister and maternal aunt. She is understandably worried about lupus because of the family history and is asking to be tested for it.

Would testing for antinuclear antibody be reasonable?

Antinuclear antibody is not a single antibody but rather a family of autoantibodies that are directed against nuclear constituents such as single- or double-stranded deoxyribonucleic acid (dsDNA), histones, centromeres, proteins complexed with ribonucleic acid (RNA), and enzymes such as topoisomerase.^17,18

Protein antigens complexed with RNA and some enzymes in the nucleus are also known as extractable nuclear antigens (ENAs). They include Ro, La, Sm, Jo-1, RNP, and ScL-70 and are named after the patient in whom they were first discovered (Robert, Lavine, Smith, and John), the antigen that is targeted (ribonucleoprotein or RNP), and the disease with which they are associated (anti-ScL-70 or antitopoisomerase in diffuse cutaneous scleroderma).

Antinuclear antibody testing is commonly requested to exclude connective tissue diseases such as lupus, but the clinician needs to be aware of the following points:

Antinuclear antibody may be encountered in conditions other than lupus

These include¹⁹:

• Other autoimmune diseases such as rheumatoid arthritis, primary Sjögren syndrome, systemic sclerosis, autoimmune thyroid disease, and myasthenia gravis
• Infection with organisms that share the epitope with self-antigens (molecular mimicry)
• Cancers
• Drugs such as hydralazine, procainamide, and minocycline.

Antinuclear antibody might also be produced by the healthy immune system from time to time to clear the nuclear debris that is extruded from aging cells.

A study in healthy individuals²⁰ reported a prevalence of positive antinuclear antibody of 32% at a titer of 1/40, 15% at a titer of 1/80, 7% at a titer of 1/160, and 3% at a titer of 1/320. Importantly, a positive result was more common among family members of patients with autoimmune connective tissue diseases.²¹ Hence, a positive antinuclear antibody result does not always mean lupus.

Antinuclear antibody testing is highly sensitive for lupus

With current laboratory methods, antinuclear antibody testing has a sensitivity close to 100%. Hence, a negative result virtually rules out lupus.

Two methods are commonly used to test for antinuclear antibody: indirect immunofluorescence and enzyme-linked immunosorbent assay (ELISA).²² While human epithelial (Hep2) cells are used as the source of antigen in immunofluorescence, purified nuclear antigens coated on multiple-well plates are used in ELISA.

Although ELISA is simpler to perform, immunofluorescence has a slightly better sensitivity (because the Hep2 cells express a wide range of antigens) and is still considered the gold standard. As expected, the higher sensitivity occurs at the cost of reduced specificity (about 60%), so antinuclear antibody will also be detected in all the other conditions listed above.²³

To improve the specificity of antinuclear antibody testing, laboratories report titers (the highest dilution of the test serum that tested positive); a cutoff of greater than 1/80 is generally considered significant.

Do not order antinuclear antibody testing indiscriminately

To sum up, the antinuclear antibody test should be requested only in patients with involvement of multiple organ systems. Although a negative result would make it extremely unlikely that the clinical presentation is due to lupus, a positive result is insufficient on its own to make a diagnosis of lupus.

Diagnosing lupus is straightforward when patients present with a specific manifestation such as inflammatory arthritis, photosensitive skin rash, hemolytic anemia, thrombocytopenia, or nephritis, or with specific antibodies such as those against dsDNA or Sm. Patients who present with nonspecific symptoms such as arthralgia or tiredness with a positive antinuclear antibody and negative anti-dsDNA and anti-Sm may present difficulties even for the specialist.^25–27

Back to our patient

Our patient denies arthralgia. She has no extraarticular symptoms such as skin rashes, oral ulcers, sicca symptoms, muscle weakness, Raynaud phenomenon, pleuritic chest pain, or breathlessness. Findings on physical examination and urinalysis are unremarkable.

Her primary care physician decides to check her complete blood cell count, erythrocyte sedimentation rate, and thyroid-stimulating hormone level. Although she is reassured that her tiredness is not due to lupus, she insists on getting an antinuclear antibody test.

Her complete blood cell counts are normal. Her erythrocyte sedimentation rate is 6 mm/hour. However, her thyroid-stimulating hormone level is elevated, and subsequent testing shows low free thyroxine and positive thyroid peroxidase antibodies. The antinuclear antibody is positive in a titer of 1/80 and negative for anti-dsDNA and anti-ENA.

We explain to her that the positive antinuclear antibody is most likely related to her autoimmune thyroid disease. She is referred to an endocrinologist.

A 24-year-old woman presents to the emergency department with acute unprovoked deep vein thrombosis in her right leg, confirmed by ultrasonography. She has no history of previous thrombosis, and the relevant family history is unremarkable. She has never been pregnant. Her platelet count is 84 × 10⁹/L (reference range 150–400), and her baseline activated partial thromboplastin time is prolonged at 62 seconds (reference range 23.0–32.4). The rest of her blood counts and her prothrombin time, liver enzyme levels, and serum creatinine level are normal.

Should this patient be tested for antiphospholipid antibodies?

Antiphospholipid antibodies are important because of their association with thrombotic risk (both venous and arterial) and pregnancy morbidity. The name is a misnomer, as these antibodies are targeted against some proteins that are bound to phospholipids and not only to the phospholipids themselves.

According to the modified Sapporo criteria for the classification of antiphospholipid syndrome,²⁸ antiphospholipid antibodies should remain persistently positive on at least 2 separate occasions at least 12 weeks apart for the result to be considered significant because some infections and drugs may be associated with the transient presence of antiphospholipid antibodies.

Screening for antiphospholipid antibodies should include testing for IgM and IgG anticardiolipin antibodies, lupus anticoagulant, and IgM and IgG beta-2 glycoprotein I antibodies.^29,30

Anticardiolipin antibodies

Anticardiolipin (aCL) antibodies may be targeted either against beta-2 glycoprotein I (beta-2GPI) that is bound to cardiolipin (a phospholipid) or against cardiolipin alone; the former is more specific. Antibodies directed against cardiolipin alone are usually transient and are associated with infections and drugs. The result is considered significant only when anticardiolipin antibodies are present in a medium to high titer (> 40 IgG phospholipid units or IgM phospholipid units, or > 99th percentile).

Lupus anticoagulant

The antibody with “lupus anticoagulant activity” is targeted against prothrombin plus phospholipid or beta-2GPI plus phospholipid. The test for it is a functional assay involving 3 steps:

Demonstrating the prolongation of a phospholipid-dependent coagulation assay like the activated partial thromboplastin time (aPTT). (This may explain the prolongation of aPTT in the patient described in the vignette.) Although the presence of lupus anticoagulant is associated with thrombosis, it is called an “anticoagulant” because of this in vitro prolongation of phospholipid-dependent coagulation assays.

Mixing study. The phospholipid-dependent coagulation assay could be prolonged because of either the deficiency of a coagulation factor or the presence of the antiphospholipid antibodies. This can be differentiated by mixing the patient’s plasma with normal plasma (which will have all the clotting factors) in a 1:1 ratio. If the coagulation assay remains prolonged after the addition of normal plasma, clotting factor deficiency can be excluded.

Addition of a phospholipid. If the prolongation of the coagulation assay is due to the presence of an antiphospholipid antibody, addition of extra phospholipid will correct this.

Beta-2 glycoprotein I antibody (anti-beta-2GPI)

The beta-2GPI that is not bound to the cardiolipin can be detected by separately testing for beta-2GPI (the anticardiolipin test only detects the beta-2GPI that is bound to the cardiolipin). The result is considered significant if beta-2GPI is present in a medium to high titer (> 99th percentile).

Studies have shown that antiphospholipid antibodies may be present in 1% to 5% of apparently healthy people in the general population.³¹ These are usually low-titer anticardiolipin or anti-beta-GPI IgM antibodies that are not associated with thrombosis or adverse pregnancy outcomes. Hence, the term antiphospholipid syndrome should be reserved for those who have had at least 1 episode of thrombosis or pregnancy morbidity and persistent antiphospholipid antibodies, and not those who have asymptomatic or transient antiphospholipid antibodies.

Triple positivity (positive anticardiolipin, lupus anticoagulant, and anti-beta-2GPI) seems to be associated with the highest risk of thrombosis, with a 10-year cumulative incidence of 37.1% (95% confidence interval [CI] 19.9–54.3) for a first thrombotic event,³² and 44.2% (95% CI 38.6–49.8) for recurrent thrombosis.³³

The association with thrombosis is stronger for lupus anticoagulant than with the other 2 antibodies, with different studies³⁴ finding an odds ratio ranging from 5 to 16. A positive lupus anticoagulant test with or without a moderate to high titer of anticardiolipin or anti-beta-2GPI IgM or IgG constitutes a high-risk profile, while a moderate to high titer of anticardiolipin or anti-beta-2GPI IgM or IgG constitutes a moderate-risk profile. A low titer of anticardiolipin or anti-beta-2GPI IgM or IgG constitutes a low-risk profile that may not be associated with thrombosis.³⁵

Antiphospholipid syndrome is important to recognize because of the need for long-term anticoagulation to prevent recurrence.³⁶ It may be primary, when it occurs on its own, or secondary, when it occurs in association with another autoimmune disease such as lupus.

Venous events in antiphospholipid syndrome most commonly manifest as lower-limb deep vein thrombosis or pulmonary embolism, while arterial events most commonly manifest as stroke or transient ischemic attack.³⁷ Obstetric manifestations may include not only miscarriage and stillbirth, but also preterm delivery, intrauterine growth retardation, and preeclampsia, all occurring due to placental insufficiency.

The frequency of antiphospholipid antibodies has been estimated as 13.5% in patients with stroke, 11% with myocardial infarction, 9.5% with deep vein thrombosis, and 6% for those with pregnancy morbidity.³⁸

Some noncriteria manifestations have also been recognized in antiphospholipid syndrome, such as thrombocytopenia, cardiac vegetations (Libman-Sachs endocarditis), livedo reticularis, and nephropathy.

Back to our patient

Our patient’s anticardiolipin IgG test is negative, while her lupus anticoagulant and beta-2GPI IgG are positive. She has no clinical or laboratory features suggesting lupus.

She is started on warfarin. After 3 months, the warfarin is interrupted for several days, and she is retested for all 3 antiphospholipid antibodies. Her beta-2GPI I IgG and lupus anticoagulant tests are again positive. Because of the persistent antiphospholipid antibody positivity and clinical history of deep vein thrombosis, her condition is diagnosed as primary antiphospholipid syndrome. She is advised to continue anticoagulant therapy indefinitely.

A 34-year-old man who is an injecting drug user presents with a 2-week history of fever, malaise, and generalized arthralgia. There are no localizing symptoms of infection. Notable findings on examination include a temperature of 38.0°C (100.4°F), needle track marks in his arms, nonblanching vasculitic rash in his legs, and a systolic murmur over the precordium.

His white blood cell count is 15.3 × 10⁹/L (reference range 3.7–11.0), and his C-reactive protein level is 234 mg/dL (normal < 3). Otherwise, results of blood cell counts, liver enzyme tests, renal function tests, urinalysis, and chest radiography are normal.

Two sets of blood cultures are drawn. Transthoracic echocardiography and the antineutrophil cytoplasmic antibody (ANCA) test are requested, as are screening tests for human immunodeficiency virus, hepatitis B, and hepatitis C.

Was the ANCA test indicated in this patient?

ANCAs are autoantibodies against antigens located in the cytoplasmic granules of neutrophils and monocytes. They are associated with small-vessel vasculitides such as granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), eosinophilic granulomatosis with polyangiitis (EGPA), and isolated pauciimmune crescentic glomerulonephritis, all collectively known as ANCA-associated vasculitis (AAV).³⁹

Laboratory methods to detect ANCA include indirect immunofluorescence and antigen-specific enzyme immunoassays. Indirect immunofluorescence only tells us whether or not an antibody that is targeting a cytoplasmic antigen is present. Based on the indirect immunofluorescent pattern, ANCA can be classified as follows:

• Perinuclear or p-ANCA (if the targeted antigen is located just around the nucleus and extends into it)
• Cytoplasmic or c-ANCA (if the targeted antigen is located farther away from the nucleus)
• Atypical ANCA (if the indirect immunofluorescent pattern does not fit with either p-ANCA or c-ANCA).

Indirect immunofluorescence does not give information about the exact antigen that is targeted; this can only be obtained by performing 1 of the antigen-specific immunoassays. The target antigen for c-ANCA is usually proteinase-3 (PR3), while that for p-ANCA could be myeloperoxidase (MPO), cathepsin, lysozyme, lactoferrin, or bactericidal permeability inhibitor. Anti-PR3 is highly specific for GPA, while anti-MPO is usually associated with MPA and EGPA. Less commonly, anti-PR3 may be seen in patients with MPA and anti-MPO in those with GPA. Hence, there is an increasing trend toward classifying ANCA-associated vasculitis into PR3-associated or MPO-associated vasculitis rather than as GPA, MPA, EGPA, or renal-limited vasculitis.⁴⁰

Several audits have shown that the ANCA test is widely misused and requested indiscriminately to rule out vasculitis. This results in a lower positive predictive value, possible harm to patients due to increased false-positive rates, and increased burden on the laboratory.^41–43 At least 2 separate groups have demonstrated that a gating policy that refuses ANCA testing in patients without clinical evidence of systemic vasculitis can reduce the number of inappropriate requests, improve the diagnostic yield, and make it more clinically relevant and cost-effective.^44,45

The clinician should bear in mind that:

Current guidelines recommend using one of the antigen-specific assays for PR3 and MPO as the primary screening method.⁴⁸ Until recently, indirect immunofluorescence was used to screen for ANCA-associated vasculitis, and positive results were confirmed by ELISA to detect ANCAs specific for PR3 and MPO,⁴⁹ but this is no longer recommended because of recent evidence suggesting a large variability between the different indirect immunofluorescent methods and improved diagnostic performance of the antigen-specific assays.

In a large multicenter study by Damoiseaux et al, the specificity with the different antigen-specific immunoassays was 98% to 99% for PR3-ANCA and 96% to 99% for MPO-ANCA.⁵⁰

ANCA-associated vasculitis should not be considered excluded if the PR3 and MPO-ANCA are negative. In the Damoiseaux study, about 11% to 15% of patients with GPA and 8% to 24% of patients with MPA tested negative for both PR3 and MPO-ANCA.⁵⁰

If the ANCA result is negative and clinical suspicion for ANCA-associated vasculitis is high, the clinician may wish to consider requesting another immunoassay method or indirect immunofluorescence. Results of indirect immunofluorescent testing results may be positive in those with a negative immunoassay, and vice versa.

Thus, the ANCA result should always be interpreted in the context of the whole clinical picture.⁵¹ Biopsy should still be considered the gold standard for the diagnosis of ANCA-associated vasculitis. The ANCA titer can help to improve clinical interpretation, because the likelihood of ANCA-associated vasculitis increases with higher levels of PR3 and MPO-ANCA.⁵²

Back to our patient

Our patient’s blood cultures grow methicillin-sensitive Staphylococcus aureus in both sets after 48 hours. Transthoracic echocardiography reveals vegetations around the tricuspid valve, with no evidence of valvular regurgitation. The diagnosis is right-sided infective endocarditis. He is started on appropriate antibiotics.

Tests for human immunodeficiency virus, hepatitis B, and hepatitis C are negative. The ANCA test is positive for MPO-ANCA at 28 IU/mL (normal < 10).

The positive ANCA is thought to be related to the infective endocarditis. His vasculitis is most likely secondary to infective endocarditis and not ANCA-associated vasculitis. The ANCA test need not have been requested in the first place.

A 22-year-old man presents to his primary care physician with a 4-month history of gradually worsening low back pain associated with early morning stiffness lasting more than 2 hours. He has no peripheral joint symptoms.

In the last 2 years, he has had 2 separate episodes of uveitis. There is a family history of ankylosing spondylitis in his father. Examination reveals global restriction of lumbar movements but is otherwise unremarkable. Magnetic resonance imaging (MRI) of the lumbar spine and sacroiliac joints is normal.

Should this patient be tested for human leukocyte antigen-B27 (HLA-B27)?

The major histocompatibility complex (MHC) is a gene complex that is present in all animals. It encodes proteins that help with immunologic tolerance. HLA simply refers to the human version of the MHC.⁵³ The HLA gene complex, located on chromosome 6, is categorized into class I, class II, and class III. HLA-B is one of the 3 class I genes. Thus, a positive HLA-B27 result simply means that the particular gene is present in that person.

HLA-B27 is strongly associated with ankylosing spondylitis, also known as axial spondyloarthropathy.⁵⁴ Other genes also contribute to the pathogenesis of ankylosing spondylitis, but HLA-B27 is present in more than 90% of patients with this disease and is by far considered the most important. The association is not as strong for peripheral spondyloarthropathy, with studies reporting a frequency of up to 75% for reactive arthritis and inflammatory bowel disease-associated arthritis, and up to 50% for psoriatic arthritis and uveitis.⁵⁵

About 9% of healthy, asymptomatic individuals may have HLA-B27, so the mere presence of this gene is not evidence of disease.⁵⁶ There may be up to a 20-fold increased risk of ankylosing spondylitis among those who are HLA-B27-positive.⁵⁷

Some HLA genes have many different alleles, each of which is given a number (explaining the number 27 that follows the B). Closely related alleles that differ from one another by only a few amino-acid substitutions are then categorized together, thus accounting for more than 100 subtypes of HLA-B27 (designated from HLA-B*2701 to HLA-B*27106). These subtypes vary in frequency among different racial groups, and the population prevalence of ankylosing spondylitis parallels the frequency of HLA-B27.⁵⁸ The most common subtype seen in white people and American Indians is B*2705. HLA-B27 is rare in blacks, explaining the rarity of ankylosing spondylitis in this population. Further examples include HLA-B*2704, which is seen in Asians, and HLA-B*2702, seen in Mediterranean populations. Not all subtypes of HLA-B27 are associated with disease, and some, like HLA-B*2706, may also be protective.

When should the clinician consider testing for HLA-B27?

Peripheral spondyloarthropathy may present with arthritis, enthesitis (eg, heel pain due to inflammation at the site of insertion of the Achilles tendon or plantar fascia), or dactylitis (“sausage” swelling of the whole finger or toe due to extension of inflammation beyond the margins of the joint). Other clues may include psoriasis, inflammatory bowel disease, history of preceding gastrointestinal or genitourinary infection, family history of similar conditions, and history of recurrent uveitis.

For the initial assessment of patients who have inflammatory back pain, plain radiography of the sacroiliac joints is considered the gold standard.⁵⁹ If plain radiography does not show evidence of sacroiliitis, MRI of the sacroiliac joints should be considered. While plain radiography can reveal only structural changes such as sclerosis, erosions, and ankylosis, MRI is useful to evaluate for early inflammatory changes such as bone marrow edema. Imaging the lumbar spine is not necessary, as the sacroiliac joints are almost invariably involved in axial spondyloarthropathy, and lesions seldom occur in the lumbar spine in isolation.⁶⁰

The diagnosis of ankylosing spondylitis previously relied on confirmatory imaging features, but based on the new International Society classification criteria,^61–63 which can be applied to patients with more than 3 months of back pain and age of onset of symptoms before age 45, patients can be classified as having 1 of the following:

• Radiographic axial spondyloarthropathy, if they have evidence of sacroiliitis on imaging plus 1 other feature of spondyloarthropathy
• Nonradiographic axial spondyloarthropathy, if they have a positive HLA-B27 plus 2 other features of spondyloarthropathy (Table 7).

These new criteria have a sensitivity of 82.9% and specificity of 84.4%.^62,63 The disease burden of radiographic and nonradiographic axial spondyloarthropathy has been shown to be similar, suggesting that they are part of the same disease spectrum. Thus, the HLA-B27 test is useful to make a diagnosis of axial spondyloarthropathy even in the absence of imaging features and could be requested in patients with 2 or more features of spondyloarthropathy. In the absence of imaging features and a negative HLA-B27 result, however, the patient cannot be classified as having axial spondyloarthropathy.

Back to our patient

The absence of radiographic evidence would not exclude axial spondyloarthropathy in our patient. The HLA-B27 test is requested because of the inflammatory back pain and the presence of 2 spondyloarthropathy features (uveitis and the family history) and is reported to be positive. His disease is classified as nonradiographic axial spondyloarthropathy.

He is started on regular naproxen and is referred to a physiotherapist. After 1 month, he reports significant symptomatic improvement. He asks if he can be retested for HLA-B27 to see if it has become negative. We tell him that there is no point in repeating it, as it is a gene and will not disappear.

SUMMARY: CONSIDER THE CLINICAL PICTURE

When approaching a patient suspected of having a rheumatologic disease, a clinician should first consider the clinical presentation and the intended purpose of each test. The tests, in general, might serve several purposes. They might help to:

Increase the likelihood of the diagnosis in question. For example, a positive rheumatoid factor or anticitrullinated peptide antibody can help diagnose rheumatoid arthritis in a patient with early polyarthritis, a positive HLA-B27 can help diagnose ankylosing spondylitis in patients with inflammatory back pain and normal imaging, and a positive ANCA can help diagnose ANCA-associated vasculitis in a patient with glomerulonephritis.

Reduce the likelihood of the diagnosis in question. For example, a negative antinuclear antibody test reduces the likelihood of lupus in a patient with joint pains.

Monitor the condition. For example DNA antibodies can be used to monitor the activity of lupus.

Plan the treatment strategy. For example, one might consider lifelong anticoagulation if antiphospholipid antibodies are persistently positive in a patient with thrombosis.

Prognosticate. For example, positive rheumatoid factor and anticitrullinated peptide antibody increase the risk of erosive rheumatoid arthritis.

If the test was requested in the absence of a clear indication and the result is positive, it is important to bear in mind the potential pitfalls associated with that test and not attach a diagnostic label prematurely. None of the tests can confirm or exclude a condition, so the results should always be interpreted in the context of the whole clinical picture.   

May et al discuss one of the most common laboratory tests we order, the complete blood cell count, and how to interpret and unlock additional information that we often overlook.

Singh et al explain the utility and limitations of assessing hepatic fibrosis in patients with known liver disease using specialized and increasingly available imaging techniques in patients with common diseases that may progress to liver failure.

Using several clinical scenarios, Suresh explores the limitations of serologic testing in patients with a potential “autoimmune” or systemic inflammatory syndrome (which, based on new consultations I see in my rheumatology clinic, seems to be virtually everyone who has experienced pain or fatigue).

The Journal also continues our ongoing series on Smart Testing that has focused on tests and testing strategies that have a strong evidence basis to support or discourage their utilization in specific settings. But in most real-life clinical scenarios, relatively little directly applicable evidence can be brought to bear on our decision process with a specific patient. Hence the ongoing need for each of us to refine our clinical reasoning skills, and to recognize the continuing challenges facing the incorporation of artificial intelligence and algorithmic practice into the management of the individual patient sitting or lying in front of us.

The challenge is to balance input from Watson, “Dr. Google,” our accumulated anecdotal and group experience, and specific data from the patient’s physical examination and provided history. All these sources are valuable, and I believe that how we thoughtfully and purposefully weigh and incorporate this information into practice defines us as the clinicians we are.

May et al discuss one of the most common laboratory tests we order, the complete blood cell count, and how to interpret and unlock additional information that we often overlook.

Singh et al explain the utility and limitations of assessing hepatic fibrosis in patients with known liver disease using specialized and increasingly available imaging techniques in patients with common diseases that may progress to liver failure.

Using several clinical scenarios, Suresh explores the limitations of serologic testing in patients with a potential “autoimmune” or systemic inflammatory syndrome (which, based on new consultations I see in my rheumatology clinic, seems to be virtually everyone who has experienced pain or fatigue).

The Journal also continues our ongoing series on Smart Testing that has focused on tests and testing strategies that have a strong evidence basis to support or discourage their utilization in specific settings. But in most real-life clinical scenarios, relatively little directly applicable evidence can be brought to bear on our decision process with a specific patient. Hence the ongoing need for each of us to refine our clinical reasoning skills, and to recognize the continuing challenges facing the incorporation of artificial intelligence and algorithmic practice into the management of the individual patient sitting or lying in front of us.

The challenge is to balance input from Watson, “Dr. Google,” our accumulated anecdotal and group experience, and specific data from the patient’s physical examination and provided history. All these sources are valuable, and I believe that how we thoughtfully and purposefully weigh and incorporate this information into practice defines us as the clinicians we are.

May et al discuss one of the most common laboratory tests we order, the complete blood cell count, and how to interpret and unlock additional information that we often overlook.

Singh et al explain the utility and limitations of assessing hepatic fibrosis in patients with known liver disease using specialized and increasingly available imaging techniques in patients with common diseases that may progress to liver failure.

Using several clinical scenarios, Suresh explores the limitations of serologic testing in patients with a potential “autoimmune” or systemic inflammatory syndrome (which, based on new consultations I see in my rheumatology clinic, seems to be virtually everyone who has experienced pain or fatigue).

The Journal also continues our ongoing series on Smart Testing that has focused on tests and testing strategies that have a strong evidence basis to support or discourage their utilization in specific settings. But in most real-life clinical scenarios, relatively little directly applicable evidence can be brought to bear on our decision process with a specific patient. Hence the ongoing need for each of us to refine our clinical reasoning skills, and to recognize the continuing challenges facing the incorporation of artificial intelligence and algorithmic practice into the management of the individual patient sitting or lying in front of us.

The challenge is to balance input from Watson, “Dr. Google,” our accumulated anecdotal and group experience, and specific data from the patient’s physical examination and provided history. All these sources are valuable, and I believe that how we thoughtfully and purposefully weigh and incorporate this information into practice defines us as the clinicians we are.

A number of conditions can mimic myositis, but clues that can point to the correct diagnosis are often present in cases involving the mimics, according to Lisa Christopher-Stine, MD.

For example, elevated levels of certain muscle enzymes are an important source of diagnostic information, Dr. Christopher-Stine, director of the Johns Hopkins Myositis Center, Baltimore, said at the Winter Rheumatology Symposium sponsored by the American College of Rheumatology.

Isolated elevations in aldolase can be seen in connective tissue–associated interstitial lung disease or in patients with fascial edema, and aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase (LDH), and creatine kinase (CK) levels can also be helpful, she explained.

The latter can also be elevated in the absence of muscle disease, for example, in healthy individuals following exercise. CK peaks at 24 hours after exercise before returning to baseline by 72 hours. In an experimental setting, a threefold increase in CK levels has been seen at 8-24 hours after exercise, Dr. Christopher-Stine said.
 

“HyperCKemia”

Trauma from causes such as intramuscular injection, electromyography (EMG), major surgery, or biopsy can also lead to increased CK levels. Motor neuron disease can also cause such increases. In one study, 75% of patients with amyotrophic lateral sclerosis had a mean twofold increase in CK levels, she said.

Asymptomatic CK elevations may also represent presymptomatic myopathies, type 1 or 2 macro-CK, manual labor occupations, or they may be idiopathic.

Race can play a role in CK levels as well. Black people tend to have higher CK levels than white people, she said, noting that one study of more than 10,000 adults showed that black race was strongly associated with CK, and that body composition largely explained differences in CK by age, but not by race/ethnicity (Medicine. Aug 2016;95[33]:e4344).

“So elevated CK may not herald any discernible illness,” she said.

Dr. Christopher-Stine described a case involving an otherwise healthy 30-year-old man with a CK level of 695 IU/L that was found incidentally. He had a desk job, no recent travel, and denied weakness, myalgias, joint pain, dysphagia, shortness of breath, and fevers. In this case, the elevated CK was felt to be secondary to his African American race given that other causes were ruled out.

Another case involved a 72-year-old man with left-arm pain. A cardiac event was ruled out, and CK was found to be about 4,500 IU/L. He reported “flare-ups” of diffuse swelling of the hands and feet. X-rays showed concerning signs of erosions. His transaminases and electromyogram were normal; he reported no weakness or myalgia; and an MRI showed no muscle edema. He was diagnosed with macro-CK, which refers to CK with an increased molecular weight. A clue to this diagnosis is a normal liver function test. In some cases, muscle/brain CK levels (CK-MB) are elevated and higher than total CK, she noted.

She presented an algorithm for the diagnostic work-up of patients presenting with elevated CK of unclear significance. Her recommended approach involves repeat CK assessment and a closer look at family history, medication, drug/toxin history, examination for weakness and neurologic abnormalities, and additional lab assessments in those whose levels remain elevated. In those in whom a diagnosis is not identified, the algorithm calls for observation every 3 months – including physical examination and labs – in asymptomatic patients with levels at less than five times the upper limit of normal, and further evaluation, including EMG with nerve-conduction velocity testing, muscle biopsy, and MRI in those with (or who later develop) marked elevation greater than five times the upper limit of normal and/or symptoms.
 

Patient assessment

The physical examination should involve localization and quantification of weakness, and assessment for fever, rash, atrophy/wasting/scooping of forearms, fasciculations, cranial nerve involvement, Raynaud’s phenomenon, nailfold capillary changes, arthritis, calcinosis, “mechanic’s hands,” signs of other autoimmune diseases, and lung crackles. Initial laboratory testing should include HIV and hepatitis B and C testing; measurement of CK, AST, ALT, aldolase, thyroid-stimulating hormone, and magnesium levels; a comprehensive metabolic panel and complete blood count; and measurement of erythrocyte sedimentation rate and C-reactive protein.

“Weakness may be secondary to a neuropathy, myopathy, or a problem at the neuropathic junction. Many causes of weakness can be readily identified by careful history taking, focused physical examination, and directed laboratory evaluation,” she said.

Features pointing toward a diagnosis of myositis include characteristic rashes, gradual symptom onset, proximal limb and truncal weakness, other connective tissue disease features such as Raynaud’s and arthritis, and the presence of lung disease, including interstitial lung disease or unexplained infiltrates, she said.

Features pointing away from a diagnosis of myositis include a family history of a similar illness, weakness that is associated with eating or fasting, neurologic signs, cranial nerve involvement, fasciculations, severe muscle cramping, early atrophy, and creatine phosphokinase levels that are either less than 2 times or more than 100 times the upper limit of normal.

Among the conditions to consider in the presence of the features that point away from a myositis diagnosis are muscular dystrophies, metabolic myopathies, and toxic (drug-induced) myopathies, to name a few, Dr. Christopher-Stine said.

She described a number of other cases to illustrate the need for – and to help develop – a differential diagnosis in patients presenting with apparent myositis.
 

Muscular dystrophies

A 38-year-old woman with limited scleroderma and anti-PM/Scl autoantibodies developed proximal weakness over 9 months and was eventually unable to walk up a flight of stairs. She had heliotrope rash and Gottron’s sign, her serum CK was 723 IU/L, and EMG showed an irritable myopathy.

Muscle biopsy showed inflammation, and she was treated with prednisone, but this led to worsening weakness. She complained of prominent fatigue and double vision at the end of the day, and these symptoms did not improve with steroids.

Anti-AChR and anti-MuSK antibodies were negative, but she had a decrement on repetitive nerve stimulation testing.

She was treated with pyridostigmine and experienced near-complete resolution of her proximal weakness and double vision. A chest CT scan showed thymic hyperplasia; thymectomy was recommended.

In another case, a 19-year-old woman who complained of leg pain after exercise was found to have intact strength but asymmetric calf hypertrophy. Her CK level was 5,000 IU/L, and she was referred to rule out acute myositis.

A quadriceps biopsy was performed and showed abnormal dystrophin immunostaining but no inflammation. A molecular genetic analysis showed deletions in Xp21 and she was diagnosed as a manifesting carrier of Duchenne muscular dystrophy. It was recommended that she be evaluated for cardiomyopathy and receive genetic counseling.

A number of other cases presented by Dr. Christopher-Stine highlighted other muscular dystrophies that can mimic myositis, such as:

• Myotonic dystrophies. These are more often type 2 than type 1. Myotonia may be subtle, cataracts are seen early in all patients, and cardiac arrhythmias are common.
• Limb girdle muscular dystrophy type 2 B (dysferlinopathy). In the legs, this often affects the gastrocnemius muscle, and this will be visible on MRI. In the arms, it most often affects the biceps, sparing the deltoids. CKs are typically very high.
• Facioscapulohumeral muscular dystrophy (FSHD). This involves facial weakness, especially obicularis oris, in 95% of cases, as well as scapular weakness and winging, inflammation on muscle biopsy in 75% of cases, and typically is endomysial or perivascular.

Metabolic myopathies

Among metabolic myopathies that can mimic myositis are disorders of carbohydrate metabolism such as McArdle’s disease, 6-phosphofructokinase deficiency, and Pompe’s disease (adult acid maltase deficiency); disorders of lipid metabolism such as carnitine deficiency and carnitine palmitoyltransferase 2 (CPT2) deficiency; and disorders of purine metabolism, such as myoadenylate deaminase deficiency.

A 27-year-old patient who complained of weakness with activity was referred for possible myositis and was found to have a CK of 3,650 IU/L that never normalized. Physical examination showed intact strength and no muscle atrophy or fasciculations, and an enzyme stain for myophosphorylase showed a normal staining pattern and complete absence of the enzyme on quadricep biopsy. A 22-year-old man with similar symptoms plus recent onset of brown/black urine after physical activity had CK of 110,000 IU/L when symptomatic, and also underwent biopsy after being referred for possible myopathy. Both patients were ultimately diagnosed with CPT2 deficiency, which is associated with risk of rhabdomyolysis triggered by prolonged exercise, diets low in carbohydrates and high in fat, or by fasting.

Myalgias are common, and CK levels are normal or only mildly elevated between episodes in CPT2 deficiency, Dr. Christopher-Stine noted.
 

Toxic myopathies

Drug-induced myopathies are among the most common etiologies of myopathy and can range from mild myalgia to massive rhabdomyolysis. They can cause mild to severe weakness and may be chronic. The mechanism of toxic injury is direct via myotoxins such as ethyl alcohol, glucocorticoids, lipid-lowering drugs, cocaine, antimalarial drugs, antipsychotic drugs, colchicine, and Ipecac syrup.

One case described by Dr. Christopher-Stine involved “statin myopathy.”

A 55-year-old man on atorvastatin complained of myalgias and brown urine, but had no definitive weakness. He had intact strength and diffuse myalgias that weren’t reproducible. His CK was 45,000 IU/L.

Statin myopathy, as seen in this patient, is usually self-limited and is not associated with autoimmunity or with anti-HMGCR autoantibody positivity.

The mechanism is unknown, but statin myopathy has an incidence of 1.2 per 10,000 patient-years. Myalgias, myositis, rhabdomyolysis, and asymptomatic hyperCKemia are commonly seen. This is in contrast to the immune-mediated necrotizing myelitis that can be secondary to statins and is responsive to immunosuppression, she noted.
 

Other myositis mimics

In addition to these common myositis mimics, certain other neurologic diseases (such as ALS and cervical myelopathy), endocrinopathies (such as hypothyroidism), and infections (like toxoplasmosis) can also be mistaken for myositis, Dr. Christopher-Stine said, noting that cases illustrating these mimics underscore the need for careful consideration of possible alternate diagnoses.

“While most noninflammatory myopathies are self-limited or have no therapies available, knowing the diagnosis can be helpful for genetic counseling of the patient and family, for mitigating risk factors, and for precluding the use of unwarranted immunosuppressive agents,” she said.

Dr. Christopher-Stine reported having intellectual property interest in a novel Inova Diagnostics autoantibody assay detection for anti-HMGCR. She was also the safety officer for the JBT-101 Trial sponsored by Corbus and funded by the National Institutes of Health.

sworcester@mdedge.com

A number of conditions can mimic myositis, but clues that can point to the correct diagnosis are often present in cases involving the mimics, according to Lisa Christopher-Stine, MD.

For example, elevated levels of certain muscle enzymes are an important source of diagnostic information, Dr. Christopher-Stine, director of the Johns Hopkins Myositis Center, Baltimore, said at the Winter Rheumatology Symposium sponsored by the American College of Rheumatology.

Isolated elevations in aldolase can be seen in connective tissue–associated interstitial lung disease or in patients with fascial edema, and aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase (LDH), and creatine kinase (CK) levels can also be helpful, she explained.

The latter can also be elevated in the absence of muscle disease, for example, in healthy individuals following exercise. CK peaks at 24 hours after exercise before returning to baseline by 72 hours. In an experimental setting, a threefold increase in CK levels has been seen at 8-24 hours after exercise, Dr. Christopher-Stine said.
 

“HyperCKemia”

Trauma from causes such as intramuscular injection, electromyography (EMG), major surgery, or biopsy can also lead to increased CK levels. Motor neuron disease can also cause such increases. In one study, 75% of patients with amyotrophic lateral sclerosis had a mean twofold increase in CK levels, she said.

Asymptomatic CK elevations may also represent presymptomatic myopathies, type 1 or 2 macro-CK, manual labor occupations, or they may be idiopathic.

Race can play a role in CK levels as well. Black people tend to have higher CK levels than white people, she said, noting that one study of more than 10,000 adults showed that black race was strongly associated with CK, and that body composition largely explained differences in CK by age, but not by race/ethnicity (Medicine. Aug 2016;95[33]:e4344).

“So elevated CK may not herald any discernible illness,” she said.

Dr. Christopher-Stine described a case involving an otherwise healthy 30-year-old man with a CK level of 695 IU/L that was found incidentally. He had a desk job, no recent travel, and denied weakness, myalgias, joint pain, dysphagia, shortness of breath, and fevers. In this case, the elevated CK was felt to be secondary to his African American race given that other causes were ruled out.

Another case involved a 72-year-old man with left-arm pain. A cardiac event was ruled out, and CK was found to be about 4,500 IU/L. He reported “flare-ups” of diffuse swelling of the hands and feet. X-rays showed concerning signs of erosions. His transaminases and electromyogram were normal; he reported no weakness or myalgia; and an MRI showed no muscle edema. He was diagnosed with macro-CK, which refers to CK with an increased molecular weight. A clue to this diagnosis is a normal liver function test. In some cases, muscle/brain CK levels (CK-MB) are elevated and higher than total CK, she noted.

She presented an algorithm for the diagnostic work-up of patients presenting with elevated CK of unclear significance. Her recommended approach involves repeat CK assessment and a closer look at family history, medication, drug/toxin history, examination for weakness and neurologic abnormalities, and additional lab assessments in those whose levels remain elevated. In those in whom a diagnosis is not identified, the algorithm calls for observation every 3 months – including physical examination and labs – in asymptomatic patients with levels at less than five times the upper limit of normal, and further evaluation, including EMG with nerve-conduction velocity testing, muscle biopsy, and MRI in those with (or who later develop) marked elevation greater than five times the upper limit of normal and/or symptoms.
 

Patient assessment

The physical examination should involve localization and quantification of weakness, and assessment for fever, rash, atrophy/wasting/scooping of forearms, fasciculations, cranial nerve involvement, Raynaud’s phenomenon, nailfold capillary changes, arthritis, calcinosis, “mechanic’s hands,” signs of other autoimmune diseases, and lung crackles. Initial laboratory testing should include HIV and hepatitis B and C testing; measurement of CK, AST, ALT, aldolase, thyroid-stimulating hormone, and magnesium levels; a comprehensive metabolic panel and complete blood count; and measurement of erythrocyte sedimentation rate and C-reactive protein.

“Weakness may be secondary to a neuropathy, myopathy, or a problem at the neuropathic junction. Many causes of weakness can be readily identified by careful history taking, focused physical examination, and directed laboratory evaluation,” she said.

Features pointing toward a diagnosis of myositis include characteristic rashes, gradual symptom onset, proximal limb and truncal weakness, other connective tissue disease features such as Raynaud’s and arthritis, and the presence of lung disease, including interstitial lung disease or unexplained infiltrates, she said.

Features pointing away from a diagnosis of myositis include a family history of a similar illness, weakness that is associated with eating or fasting, neurologic signs, cranial nerve involvement, fasciculations, severe muscle cramping, early atrophy, and creatine phosphokinase levels that are either less than 2 times or more than 100 times the upper limit of normal.

Among the conditions to consider in the presence of the features that point away from a myositis diagnosis are muscular dystrophies, metabolic myopathies, and toxic (drug-induced) myopathies, to name a few, Dr. Christopher-Stine said.

She described a number of other cases to illustrate the need for – and to help develop – a differential diagnosis in patients presenting with apparent myositis.
 

Muscular dystrophies

A 38-year-old woman with limited scleroderma and anti-PM/Scl autoantibodies developed proximal weakness over 9 months and was eventually unable to walk up a flight of stairs. She had heliotrope rash and Gottron’s sign, her serum CK was 723 IU/L, and EMG showed an irritable myopathy.

Muscle biopsy showed inflammation, and she was treated with prednisone, but this led to worsening weakness. She complained of prominent fatigue and double vision at the end of the day, and these symptoms did not improve with steroids.

Anti-AChR and anti-MuSK antibodies were negative, but she had a decrement on repetitive nerve stimulation testing.

She was treated with pyridostigmine and experienced near-complete resolution of her proximal weakness and double vision. A chest CT scan showed thymic hyperplasia; thymectomy was recommended.

In another case, a 19-year-old woman who complained of leg pain after exercise was found to have intact strength but asymmetric calf hypertrophy. Her CK level was 5,000 IU/L, and she was referred to rule out acute myositis.

A quadriceps biopsy was performed and showed abnormal dystrophin immunostaining but no inflammation. A molecular genetic analysis showed deletions in Xp21 and she was diagnosed as a manifesting carrier of Duchenne muscular dystrophy. It was recommended that she be evaluated for cardiomyopathy and receive genetic counseling.

A number of other cases presented by Dr. Christopher-Stine highlighted other muscular dystrophies that can mimic myositis, such as:

• Myotonic dystrophies. These are more often type 2 than type 1. Myotonia may be subtle, cataracts are seen early in all patients, and cardiac arrhythmias are common.
• Limb girdle muscular dystrophy type 2 B (dysferlinopathy). In the legs, this often affects the gastrocnemius muscle, and this will be visible on MRI. In the arms, it most often affects the biceps, sparing the deltoids. CKs are typically very high.
• Facioscapulohumeral muscular dystrophy (FSHD). This involves facial weakness, especially obicularis oris, in 95% of cases, as well as scapular weakness and winging, inflammation on muscle biopsy in 75% of cases, and typically is endomysial or perivascular.

Metabolic myopathies

Among metabolic myopathies that can mimic myositis are disorders of carbohydrate metabolism such as McArdle’s disease, 6-phosphofructokinase deficiency, and Pompe’s disease (adult acid maltase deficiency); disorders of lipid metabolism such as carnitine deficiency and carnitine palmitoyltransferase 2 (CPT2) deficiency; and disorders of purine metabolism, such as myoadenylate deaminase deficiency.

A 27-year-old patient who complained of weakness with activity was referred for possible myositis and was found to have a CK of 3,650 IU/L that never normalized. Physical examination showed intact strength and no muscle atrophy or fasciculations, and an enzyme stain for myophosphorylase showed a normal staining pattern and complete absence of the enzyme on quadricep biopsy. A 22-year-old man with similar symptoms plus recent onset of brown/black urine after physical activity had CK of 110,000 IU/L when symptomatic, and also underwent biopsy after being referred for possible myopathy. Both patients were ultimately diagnosed with CPT2 deficiency, which is associated with risk of rhabdomyolysis triggered by prolonged exercise, diets low in carbohydrates and high in fat, or by fasting.

Myalgias are common, and CK levels are normal or only mildly elevated between episodes in CPT2 deficiency, Dr. Christopher-Stine noted.
 

Toxic myopathies

Drug-induced myopathies are among the most common etiologies of myopathy and can range from mild myalgia to massive rhabdomyolysis. They can cause mild to severe weakness and may be chronic. The mechanism of toxic injury is direct via myotoxins such as ethyl alcohol, glucocorticoids, lipid-lowering drugs, cocaine, antimalarial drugs, antipsychotic drugs, colchicine, and Ipecac syrup.

One case described by Dr. Christopher-Stine involved “statin myopathy.”

A 55-year-old man on atorvastatin complained of myalgias and brown urine, but had no definitive weakness. He had intact strength and diffuse myalgias that weren’t reproducible. His CK was 45,000 IU/L.

Statin myopathy, as seen in this patient, is usually self-limited and is not associated with autoimmunity or with anti-HMGCR autoantibody positivity.

The mechanism is unknown, but statin myopathy has an incidence of 1.2 per 10,000 patient-years. Myalgias, myositis, rhabdomyolysis, and asymptomatic hyperCKemia are commonly seen. This is in contrast to the immune-mediated necrotizing myelitis that can be secondary to statins and is responsive to immunosuppression, she noted.
 

Other myositis mimics

In addition to these common myositis mimics, certain other neurologic diseases (such as ALS and cervical myelopathy), endocrinopathies (such as hypothyroidism), and infections (like toxoplasmosis) can also be mistaken for myositis, Dr. Christopher-Stine said, noting that cases illustrating these mimics underscore the need for careful consideration of possible alternate diagnoses.

“While most noninflammatory myopathies are self-limited or have no therapies available, knowing the diagnosis can be helpful for genetic counseling of the patient and family, for mitigating risk factors, and for precluding the use of unwarranted immunosuppressive agents,” she said.

Dr. Christopher-Stine reported having intellectual property interest in a novel Inova Diagnostics autoantibody assay detection for anti-HMGCR. She was also the safety officer for the JBT-101 Trial sponsored by Corbus and funded by the National Institutes of Health.

sworcester@mdedge.com

A number of conditions can mimic myositis, but clues that can point to the correct diagnosis are often present in cases involving the mimics, according to Lisa Christopher-Stine, MD.

For example, elevated levels of certain muscle enzymes are an important source of diagnostic information, Dr. Christopher-Stine, director of the Johns Hopkins Myositis Center, Baltimore, said at the Winter Rheumatology Symposium sponsored by the American College of Rheumatology.

Isolated elevations in aldolase can be seen in connective tissue–associated interstitial lung disease or in patients with fascial edema, and aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase (LDH), and creatine kinase (CK) levels can also be helpful, she explained.

The latter can also be elevated in the absence of muscle disease, for example, in healthy individuals following exercise. CK peaks at 24 hours after exercise before returning to baseline by 72 hours. In an experimental setting, a threefold increase in CK levels has been seen at 8-24 hours after exercise, Dr. Christopher-Stine said.
 

“HyperCKemia”

Trauma from causes such as intramuscular injection, electromyography (EMG), major surgery, or biopsy can also lead to increased CK levels. Motor neuron disease can also cause such increases. In one study, 75% of patients with amyotrophic lateral sclerosis had a mean twofold increase in CK levels, she said.

Asymptomatic CK elevations may also represent presymptomatic myopathies, type 1 or 2 macro-CK, manual labor occupations, or they may be idiopathic.

Race can play a role in CK levels as well. Black people tend to have higher CK levels than white people, she said, noting that one study of more than 10,000 adults showed that black race was strongly associated with CK, and that body composition largely explained differences in CK by age, but not by race/ethnicity (Medicine. Aug 2016;95[33]:e4344).

“So elevated CK may not herald any discernible illness,” she said.

Dr. Christopher-Stine described a case involving an otherwise healthy 30-year-old man with a CK level of 695 IU/L that was found incidentally. He had a desk job, no recent travel, and denied weakness, myalgias, joint pain, dysphagia, shortness of breath, and fevers. In this case, the elevated CK was felt to be secondary to his African American race given that other causes were ruled out.

Another case involved a 72-year-old man with left-arm pain. A cardiac event was ruled out, and CK was found to be about 4,500 IU/L. He reported “flare-ups” of diffuse swelling of the hands and feet. X-rays showed concerning signs of erosions. His transaminases and electromyogram were normal; he reported no weakness or myalgia; and an MRI showed no muscle edema. He was diagnosed with macro-CK, which refers to CK with an increased molecular weight. A clue to this diagnosis is a normal liver function test. In some cases, muscle/brain CK levels (CK-MB) are elevated and higher than total CK, she noted.

She presented an algorithm for the diagnostic work-up of patients presenting with elevated CK of unclear significance. Her recommended approach involves repeat CK assessment and a closer look at family history, medication, drug/toxin history, examination for weakness and neurologic abnormalities, and additional lab assessments in those whose levels remain elevated. In those in whom a diagnosis is not identified, the algorithm calls for observation every 3 months – including physical examination and labs – in asymptomatic patients with levels at less than five times the upper limit of normal, and further evaluation, including EMG with nerve-conduction velocity testing, muscle biopsy, and MRI in those with (or who later develop) marked elevation greater than five times the upper limit of normal and/or symptoms.
 

Patient assessment

The physical examination should involve localization and quantification of weakness, and assessment for fever, rash, atrophy/wasting/scooping of forearms, fasciculations, cranial nerve involvement, Raynaud’s phenomenon, nailfold capillary changes, arthritis, calcinosis, “mechanic’s hands,” signs of other autoimmune diseases, and lung crackles. Initial laboratory testing should include HIV and hepatitis B and C testing; measurement of CK, AST, ALT, aldolase, thyroid-stimulating hormone, and magnesium levels; a comprehensive metabolic panel and complete blood count; and measurement of erythrocyte sedimentation rate and C-reactive protein.

“Weakness may be secondary to a neuropathy, myopathy, or a problem at the neuropathic junction. Many causes of weakness can be readily identified by careful history taking, focused physical examination, and directed laboratory evaluation,” she said.

Features pointing toward a diagnosis of myositis include characteristic rashes, gradual symptom onset, proximal limb and truncal weakness, other connective tissue disease features such as Raynaud’s and arthritis, and the presence of lung disease, including interstitial lung disease or unexplained infiltrates, she said.

Features pointing away from a diagnosis of myositis include a family history of a similar illness, weakness that is associated with eating or fasting, neurologic signs, cranial nerve involvement, fasciculations, severe muscle cramping, early atrophy, and creatine phosphokinase levels that are either less than 2 times or more than 100 times the upper limit of normal.

Among the conditions to consider in the presence of the features that point away from a myositis diagnosis are muscular dystrophies, metabolic myopathies, and toxic (drug-induced) myopathies, to name a few, Dr. Christopher-Stine said.

She described a number of other cases to illustrate the need for – and to help develop – a differential diagnosis in patients presenting with apparent myositis.
 

Muscular dystrophies

A 38-year-old woman with limited scleroderma and anti-PM/Scl autoantibodies developed proximal weakness over 9 months and was eventually unable to walk up a flight of stairs. She had heliotrope rash and Gottron’s sign, her serum CK was 723 IU/L, and EMG showed an irritable myopathy.

Muscle biopsy showed inflammation, and she was treated with prednisone, but this led to worsening weakness. She complained of prominent fatigue and double vision at the end of the day, and these symptoms did not improve with steroids.

Anti-AChR and anti-MuSK antibodies were negative, but she had a decrement on repetitive nerve stimulation testing.

She was treated with pyridostigmine and experienced near-complete resolution of her proximal weakness and double vision. A chest CT scan showed thymic hyperplasia; thymectomy was recommended.

In another case, a 19-year-old woman who complained of leg pain after exercise was found to have intact strength but asymmetric calf hypertrophy. Her CK level was 5,000 IU/L, and she was referred to rule out acute myositis.

A quadriceps biopsy was performed and showed abnormal dystrophin immunostaining but no inflammation. A molecular genetic analysis showed deletions in Xp21 and she was diagnosed as a manifesting carrier of Duchenne muscular dystrophy. It was recommended that she be evaluated for cardiomyopathy and receive genetic counseling.

A number of other cases presented by Dr. Christopher-Stine highlighted other muscular dystrophies that can mimic myositis, such as:

• Myotonic dystrophies. These are more often type 2 than type 1. Myotonia may be subtle, cataracts are seen early in all patients, and cardiac arrhythmias are common.
• Limb girdle muscular dystrophy type 2 B (dysferlinopathy). In the legs, this often affects the gastrocnemius muscle, and this will be visible on MRI. In the arms, it most often affects the biceps, sparing the deltoids. CKs are typically very high.
• Facioscapulohumeral muscular dystrophy (FSHD). This involves facial weakness, especially obicularis oris, in 95% of cases, as well as scapular weakness and winging, inflammation on muscle biopsy in 75% of cases, and typically is endomysial or perivascular.

Metabolic myopathies

Among metabolic myopathies that can mimic myositis are disorders of carbohydrate metabolism such as McArdle’s disease, 6-phosphofructokinase deficiency, and Pompe’s disease (adult acid maltase deficiency); disorders of lipid metabolism such as carnitine deficiency and carnitine palmitoyltransferase 2 (CPT2) deficiency; and disorders of purine metabolism, such as myoadenylate deaminase deficiency.

A 27-year-old patient who complained of weakness with activity was referred for possible myositis and was found to have a CK of 3,650 IU/L that never normalized. Physical examination showed intact strength and no muscle atrophy or fasciculations, and an enzyme stain for myophosphorylase showed a normal staining pattern and complete absence of the enzyme on quadricep biopsy. A 22-year-old man with similar symptoms plus recent onset of brown/black urine after physical activity had CK of 110,000 IU/L when symptomatic, and also underwent biopsy after being referred for possible myopathy. Both patients were ultimately diagnosed with CPT2 deficiency, which is associated with risk of rhabdomyolysis triggered by prolonged exercise, diets low in carbohydrates and high in fat, or by fasting.

Myalgias are common, and CK levels are normal or only mildly elevated between episodes in CPT2 deficiency, Dr. Christopher-Stine noted.
 

Toxic myopathies

Drug-induced myopathies are among the most common etiologies of myopathy and can range from mild myalgia to massive rhabdomyolysis. They can cause mild to severe weakness and may be chronic. The mechanism of toxic injury is direct via myotoxins such as ethyl alcohol, glucocorticoids, lipid-lowering drugs, cocaine, antimalarial drugs, antipsychotic drugs, colchicine, and Ipecac syrup.

One case described by Dr. Christopher-Stine involved “statin myopathy.”

A 55-year-old man on atorvastatin complained of myalgias and brown urine, but had no definitive weakness. He had intact strength and diffuse myalgias that weren’t reproducible. His CK was 45,000 IU/L.

Statin myopathy, as seen in this patient, is usually self-limited and is not associated with autoimmunity or with anti-HMGCR autoantibody positivity.

The mechanism is unknown, but statin myopathy has an incidence of 1.2 per 10,000 patient-years. Myalgias, myositis, rhabdomyolysis, and asymptomatic hyperCKemia are commonly seen. This is in contrast to the immune-mediated necrotizing myelitis that can be secondary to statins and is responsive to immunosuppression, she noted.
 

Other myositis mimics

In addition to these common myositis mimics, certain other neurologic diseases (such as ALS and cervical myelopathy), endocrinopathies (such as hypothyroidism), and infections (like toxoplasmosis) can also be mistaken for myositis, Dr. Christopher-Stine said, noting that cases illustrating these mimics underscore the need for careful consideration of possible alternate diagnoses.

“While most noninflammatory myopathies are self-limited or have no therapies available, knowing the diagnosis can be helpful for genetic counseling of the patient and family, for mitigating risk factors, and for precluding the use of unwarranted immunosuppressive agents,” she said.

Dr. Christopher-Stine reported having intellectual property interest in a novel Inova Diagnostics autoantibody assay detection for anti-HMGCR. She was also the safety officer for the JBT-101 Trial sponsored by Corbus and funded by the National Institutes of Health.

sworcester@mdedge.com