The Interplay of Disease Modifying Anti Rheumatic Drugs and Tuberculin Skin Test

Abstract

Objective: The study was conducted to determine whether synthetic Disease-Modifying Anti Rheumatic Drugs (DMARDs) suppress the latency of Tuberculosis (TB) infection in Rheumatoid Arthritis (RA) patients along with other variables.

Methods: This was done through Tuberculin Skin Test (TST) using purified protein derivative (PPD) in a cohort of RA patients. The TST was taken positive when induration post-PPD injection was ≥ 5mm and negative or anergic when it was < 5mm. We included 100 patients (N = 100).

Results: The prevalence of positive TST was 36%, while 64% presented a negative result. Negative TST was significantly associated with steroid usage (39.4%, 95% CI: 28.4%-51.4%). Anergic (TST negative) and non-anergic (TST positive) patients were separated into groups, and a new analysis was conducted with elaboration on DMARDs used.

Conclusion: The use of steroids was associated with TST negativity, The same is not true with use of methotrexate or other DMARDs. Thus TST should be interpreted with caution, especially before starting biologicals.

Keywords: DMARD; Rheumatoid arthritis; TST; anergic.; latent tuberculosis; poly-arthritis.