Despite following guidelines aimed at reducing the likelihood of tuberculosis infection in patients with psoriasis treated with tumor necrosis factor antagonists, a French study has identified a number of active TB cases in this patient group.
The nationwide retrospective study identified 12 cases of tuberculosis in individuals with psoriasis during treatment with a TNF-antagonist between 2006 and 2014 – 9 men and 3 women, whose mean age was 49 years – according to Dr. E. Guinard of the dermatology service, CHU Toulouse Larrey at Paul Sabatier University, Toulouse, France, and associates (J Eur Acad Dermatol Venereol. 2016 Jun 3. doi: 10.1111/jdv.13633).
The investigators identified the cases from a national pharmacosurveillance database and by contacting members of the psoriasis research group in France’s national dermatology society and the national college of French dermatology professors.
Before starting anti-TNF therapy, all 12 patients had been screened for latent TB based on French guidelines: three patients were tested with the tuberculosis skin test alone, six were tested with QuantiFERON-TB Gold test, and three patients had both the skin test and QuantiFERON-TB. Each had a pretreatment chest x-ray.
Based on this testing, three were diagnosed with latent TB and received chemoprophylaxis; the other nine patients tested negative.
Information on TB risk factors was not available for all 12 cases, but three people had had contact with someone with TB during treatment. Three of the individuals had traveled to or were born in areas where TB was endemic, and one patient had had a case of TB in the family in the year before starting anti-TNF therapy. Nine patients had a known history of BCG vaccination, the investigators said.
The time between starting anti-TNF therapy and the appearance of TB symptoms ranged from 2 to 176 weeks (mean, 23 weeks), and diagnosis was based on clinical signs – such as fever, night sweats, and cough – and on imaging and laboratory investigations. Most (10) of the cases were extrapulmonary presentations, and two were pleuropulmonary. When diagnosed with tuberculosis, seven of the patients were being treated with infliximab, four were being treated with adalimumab, and one was being treated with certolizumab. All stopped anti-TNF therapy once they were diagnosed with tuberculosis.
Dr. Guinard and associates noted that the low sensitivity of Mycobacterium tuberculosis diagnostic tests was “a striking feature” of these cases. Only one-third of the patients showed a positive direct Ziehl-Neelsen stain for acid-fast bacilli and half had a positive culture.
“According to this study and published experience, in a patient with suggestive symptoms, a negative Mycobacterium tuberculosis test should not delay the decision to initiate anti-tuberculosis treatment,” they wrote. “This is particularly important considering the high mortality of tuberculosis in patients treated with TNF antagonists,” which ranges from 6%-17%, they added.
Two of the twelve patients – aged 77 and 32 years – died of disseminated tuberculosis disease during treatment for TB.
“This is the largest study of tuberculosis in psoriasis patients treated with TNF antagonists,” according to the authors.
No conflicts of interest were declared, and the study had no funding source.