Conversion of Tuberculosis Screening Tests During Biologic Therapy Among Veteran Patient Population With Rheumatic Disease.

Objective: The optimal strategy to detect the development of tuberculosis TB) in subjects receiving biologic agents is not clear. The recommendations vary because there is wide variation in the reported rate of seroconversion in various parts of the world. There is a scarcity of long-term studies regarding seroconversion of TB in the United States among these patients.

Methods: This is a retrospective study among veteran populations with rheumatic diseases who received various biologic agents between 2003 and 2014. Subjects who had repeated TB screening tests and adequate follow-up periods were considered for the study.

Results: Out of 298 subjects who received biologic agents, 123 were considered for the study. After the initial negative screening test by tuberculin skin test (TST), patients were screened on an average of 1.2 years for 4.3 to 12 years. A total of 420 tests were performed, which were combination of TST and QuantiFERON-TB gold in-Tube assay. Only 1 out of 123 subjects (0.8%) seroconverted to latent TB and was treated with isoniazid for 9 months.

Conclusion: Our results are in line with a few other studies reported from the United States. We conclude that in areas with low prevalence of TB the seroconversion rate is extremely low and annual testing is unnecessary in low-risk patient populations.