Tuberculin Skin Reaction among Healthy People and Patients with Arthritis in the Southern Israeli Region*

Abstract

Introduction: Reactivation of latent tuberculosis is a major complication of tumor necrosis factor alpha (TNF-alpha) inhibitors. Therefore, screening for latent TB is recommended before initiation of this treatment. The aim of the study was to compare Tuberculosis skin test (TST) size reaction between healthy people and patients, with Rheumatoid arthritis (RA), Ankylosising spondylitis (AnS) and Psoriatic arthritis (PsA). Patients and Methods: Results of TST of 133 healthy subjects were compared with the results of TST of 79 patients, suffering from RA, AnS and PsA. A χ 2 test was used to compare the difference between the groups. A value of p < 0.05 was considered significant. Active tuberculosis (TB) was excluded by chest X-ray and through patient's history. The results of TST reaction were grouped according to the CDC's (Centers for Disease Control and prevention) recommendation, e.g. 0-4 mm, 5-9 mm, 10-15 mm and >15 mm. Results: Among RA patients 80% received Methotrexate (MTX), 50% Prednisone and 20% other DMARDs. 20% of patients suffering from AnS received MTX, 80%-NSAIDs, and among patients with PsA 70% received MTX, 30%-Salazopirin. There was no significant difference in history of bacilli Calmette-Guerine vaccination between the groups. There was no significant difference in TST reaction distribution between healthy subjects and patients with RAp > 0.5. TST reaction distribution differed significantly between healthy people and AnS (p < 0.05) and PsA (p < 0.001) patients. The overall tendency in these two patients' groups was towards high positive TST, especially among PsA patients. Conclusion: Our results showed that RA patients may present TST reaction as healthy people. The high percent of our AnS and PsA patients that showed TST reaction above 15 mm need further exploration. We conclude that it may be not appropriate to use TST to recognize LTBI in our population.