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

OBJECTIVE: The study was conducted to determine whether synthetic disease modifying Anti Rheumatic drugs (DMARDs) suppresses 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 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 in groups, and a new analysis was done with elaboration on DMARDs used.

CONCLUSION: Steroid use and not treatment with methotrexate or other DMARDs was associated with TST negativity and thus TST should be interpreted with caution especially before starting biologicals.