From the Journals

Stress tests before knee, hip replacement surgeries down, with no ill effects



Cardiac stress testing before hip and knee replacements has dropped steadily since 2006, according to results from a new study that also showed major cardiac complications to be low in the absence of stress testing – even among people with established risk factors.

Dr. Daniel S. Rubin of the University of Chicago

Dr. Daniel S. Rubin

Routine stress testing before noncardiac surgeries has come under fire in recent decades as an overuse of resources and a burden on patients. Practice guidelines issued in 2007 and 2014 by the American College of Cardiology and the American Heart Association sought to limit the use of preoperative testing to patients with specific cardiovascular risk factors who might have their management changed by the test results.

For their study, published online in JAMA Cardiology, Daniel S. Rubin, MD, of the University of Chicago and colleagues looked at employee-based insurance data, which included Medicare Advantage claims, for more than 800,000 total hip or knee arthroplasties (28% hip and 72% knee replacements) conducted between 2004 and 2017.

While some 10% of the cohort (mean age 62, 58% women) received a stress test in the 2 months before surgery, the investigators found that the frequency of preoperative stress testing dropped annually starting in late 2006, when it peaked at about 14%, to about 7% in 2017. Older age, male sex and a Revised Cardiac Risk Index score of 1 or greater were all associated with a higher likelihood of being tested.

The overall frequency of myocardial infarction or cardiac arrest was 0.24%, occurring in 1,677 of 686,067 patients. While the rate was higher in patients with at least one RCRI condition, this did not differ significantly between those who received a preoperative stress test and those who did not (0.60%; 221 of 36,554 vs. 0.57%; 694 of 122,466 patients.

The 2007 and 2014 ACC/AHA guidelines make clear that patients with zero RCRI conditions – which comprise a history of ischemic heart disease, heart failure, insulin therapy for diabetes, cerebrovascular disease, or chronic kidney disease – should not receive a stress test before an intermediate-risk surgery such as a hip or knee replacement. But in this study, Dr. Rubin and his colleagues found that almost half of patients who had no RCRI risk factors were stress tested anyway. This means, Dr. Rubin said in an interview, that “there’s still room for improvement” in reducing testing.

“I never want to question how a physician chooses to practice, but I have to applaud physicians for reining in the use of this test. We’re using less of this test and yet the incidence of myocardial infarction and cardiac arrest is also going down, which also calls into question whether we’re getting better at choosing the right patients for the test; or the test doesn’t impact outcomes; or overall health of these patients is improving,” he said.

One surprise finding in the study, Dr. Rubin noted, was a higher rate of complications among people without RCRI conditions who were stress tested, compared with those who were not, with a mean complication rate of 0.27%, compared with 0.14% among those who did not receive a test (P < .001). “The RCRI doesn’t capture certain things,” Dr. Rubin said. “And we know that no risk stratification tool is going to capture everything.”

The RCRI, he noted, is based on a clinical history. “If you haven’t been diagnosed yet, it won’t appear as a risk factor, even if you’re clearly at risk. The question then becomes for a physician, do you do the test or not? On a day-to-day basis it’s hard to make that decision because you want what’s best for the individual patient – and it’s hard to generalize from a study of 800,000 people what’s right for that one patient. That said, it doesn’t appear that stress testing improves outcomes and a decrease in testing appears appropriate.”

Joshua A. Beckman, MD, professor of medicine and director of vascular medicine at Vanderbilt University in Nashville, Tenn.

Dr. Joshua A. Beckman

Dr. Rubin and his colleagues described as a weakness of their study that it did not capture the full scope of preoperative stress testing among Medicare patients, who are older and therefore more likely to be tested.

That the 2007 and 2014 practice guidelines bore on the drop in testing was not demonstrated by Dr. Rubin and colleagues’ study, which saw declines begin even before the guidelines were published. Nonetheless, the results appear to validate the approach advocated in the guidelines, said guideline coauthor Joshua Beckman, MD, of Vanderbilt University, whose recent research has focused on identifying risk factors for MI after noncardiac surgery.

“I hope that the guidelines have helped in changing the culture for the use of preoperative stress testing as a regular thing,” Dr. Beckman said in an interview. “In fact, the guidelines say you shouldn’t do anything before an operation that you wouldn’t do anyway. So these findings are certainly in agreement with what we’re suggesting and support the idea that unless you have something that is unstable or active, stress testing isn’t likely to help.”

Annemarie Thompson, MD, of Duke University in Durham, N.C., another coauthor on the 2014 guidelines, commented in an interview that Dr. Rubin and colleagues’ findings of a doubled rate of complications among people without RCRI conditions who were stress tested, compared with those who were not might mean something “other than just sheer overuse or overordering of tests inappropriately.”

Rather, she said, physicians might be seeing something in the clinic that cannot be captured by a screening tool reliant on existing diagnoses. “Maybe when they’re sitting in front of you in a clinic, they’re so immobile that you’re left wondering. Or maybe they haven’t been seen by a doctor in a long time,” Dr. Thompson said. “So they don’t have diagnoses if they haven’t been followed. I think what [this finding] shows is that clinicians are detecting something. They may not know what it is. But we have to give a little wiggle room to the clinician who is sitting there looking at a patient who looks like they may not make it through surgery.”

Dr. Thompson said it would be helpful, after a big-data study like this one, to go through the clinical histories of those patients – in this study fewer than 100 – who had no RCRI risk factors and yet were stress tested and ended up having complications. “Until then we’re not going to solve the mystery,” she said. “But it’s a very, very interesting study.”

Dr. Rubin is the president of DRDR Mobile Health, a company that creates mobile applications for health care and from which he has not received compensation. One of his coauthors on the study, Dr. Peter Nagele, reported fee income from Roche Diagnostics. Dr. Beckman disclosed personal fees from AstraZeneca, Boehringer Ingelheim, Bristol Myers Squibb, and other pharmaceutical manufacturers. Dr. Thompson has no disclosures.

SOURCE: Rubin et al. JAMA Cardiol. 2020 Sep 30. doi: 10.1001/jamacardio.2020.4311.

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