Prevalence of positive tuberculin skin test in a Brazilian sample of rheumatoid arthritis and spondylarthritis patients.

Abstract

Patients with rheumatic diseases have an increased risk of infections, especially tuberculosis. In this study, we aimed to recognize the positivity rate of tuberculosis skin test in patients with rheumatoid arthritis and spondyloarthritis and the characteristics of the patients with positive results. Retrospective study of tuberculosis skin test results in patients followed from 2004 to 2021 in a single rheumatology unit. Data related to clinical and epidemiological features, along with treatment information referring to the period in which the tuberculosis skin test was performed, were collected from patients' charts. A total of 723 tests were identified (448 tests in 269 rheumatoid arthritis patients and 275 in 174 spondyloarthritis patients). In the rheumatoid arthritis sample, 31/275 (11.5%) individuals had positive tests, and in the spondyloarthritis, 38/174 (21.8%) had positive tests. In the rheumatoid arthritis sample, patients with positive tuberculosis skin tests used a higher dose of methotrexate than those with negative results (median of 25 mg/week versus median of 20 mg/week respectively; p=0.02). In the spondyloarthritis sample, tuberculosis skin test positivity was associated with alcohol ingestion (13.1% versus 2.9% in users and non-users respectively; p=0.02) and sulfasalazine use (15.7% of positivity in users versus 5% in non-users; p=0.01). The tuberculosis skin test-positive prevalence in rheumatoid arthritis was lower than in the spondyloarthritis sample. Patients with rheumatoid arthritis using a higher dosage of methotrexate or with spondyloarthritis using sulfasalazine had more frequency of tuberculosis skin test positivity and should be carefully followed by the attending physician in order to avoid the appearance of full-blown tuberculosis.