Juvenile idiopathic arthritis (JIA) is the most common rheumatologic disease in pediatric age group. Mycobacterium tuberculosis infection (TB) is an important cause of mortality and morbidity in patients with inflammatory rheumatologic disease. The objective of this study is to determine to what extent active disease and use of drugs in JIA affects response to PPD skin test and thus to investigate the significance of PPD skin test in the diagnosis of latent TB. 77 children diagnosed with JIA according to ILAR diagnostic criteria and routinely followed by our rheumatology clinic were included in the patient group. Patients were grouped according to subtypes of disease, activity status and drugs they used. Control group was formed from 58 healthy children. PPD skin test was applied to each subject and the number of BCG scars of all cases was recorded. We found no significant difference in PPD induration diameters between JIA and control group (p > 0.05). The number of BCG scar is similar in both groups. In the control group, age and number of BCG scars and PPD skin test diameter are positively correlated. But there is no such significant relationship in patients with JIA (p > 0.05). PPD induration diameter of patients with active disease is significantly shorter than patients in remission (p > 0.05). PPD induration diameter of patients treated with steroid and disease modifying anti-rheumatic drug (DMARD) and underwent remission were not significantly different from the control group. When compared with patients using other drugs, patients on remission using steroid and DMARD have shorter PPD induration diameter. Activity of disease and drugs used (steroid, DMARD) affects PPD response. In the diagnosis of latent TB, normal range of PPD diameter in healthy child changes in JIA patient with active disease. That the PPD diameter is shorter than normal range could indicate underlying TB infection. This fact should be considered in the follow-up of the patients with JIA.
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