Objectives: Interpretation of tuberculin reactions in tuberculosis prophylaxis is somewhat controversial among the patients with rheumatoid arthritis. The tuberculin skin test is used worldwide to assess the tuberculosis infections. Our aim was to determine the tuberculin skin test positivity among Turkish rheumatoid arthritis patients in this respect. Immunosuppressives and anti-TNF agents can cause reactivation of latent tuberculosis infection. Thus it is to be determined which patients should be put on prophylaxis based on PPD results.Methods: Fifty-six patients (ACR 1987) (46 female, 10 male; mean age 54.9 ± 9.8) were included in this study. None of the patients had evidence of active tuberculosis infections at the time of study. A delayed type hypersensitivity response to tuberculin was examined with standard 0.1 ml tuberculin (containing 2 mg of PPD) in all patients. Responses with an enduration diameter of ≥10 mm at the end of 72 hours were considered to be positive.Results: Tuberculin response was positive in 36 patients (%64.3). Mean induration size was 15.4±8.8 mm (0-40 mm) in all patients. Fifty, 75 and 90 percentiles of the induration size of whole group were 15 mm, 22mm, and 25 mm respectively. Among the PPD positive patients %33.3 had an induration size 10-14 mm, % 17.9 had 15-19 mm and %48.7 had 20 mm and over. There was no significant difference between the patients with positive and negative tuberculin test results according to age, gender, duration of disease, tender and swollen joint counts, erythrocyte sedimentation rate (ESR) and C-reactive protein level. Fifteen patients in the tuberculin negative and 21 patients in the positive group (mean doses 7.9 ± 2.3 mg/d and 8.0 ± 3.9mg/d respectively) were using corticosteroid (CS) at the time of skin test. It seems neither CS usage nor the dosage, affected the test results (p=0.90 and 0.93 respectively). Although there was no significant difference according to induration size between patients with and without immunosuppressive treatment including CS, methotrexate, cyclosporine or leflunomide (mean induration sizes: 14.8±9.0 and 16.8±8.4 mm respectively and p=0.327), immunosuppressive therapy seems to decrease the test positivity (%59.5 vs %73.7 and p=0.293) but has no statistical significance. None of the patients were using biologic agents.Conclusion: Immunosuppressive and low dose CS therapy seems to decrease the response to tuberculin skin test. These data indicate that those population with high coverage of BCG vaccination and patients with immunosuppressives and low dose CS defining the PPD test positivity, needs further studies.

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