Risk Factors for tuberculosis in patients on anti-TNF treatment

Although latent tuberculosis infection (LTBI) treatment is given before starting anti-TNF treatment, tuberculosis (TB) still develops in these patients. The incidence of hepatotoxicity associated with INH treatment is not known in this group of patients. The aim of this study was to determine the risk factors for the development of tuberculosis and the safety of LTBI in such patients. All patients (n=389, 47.0 ± 13.4 years) given anti-TNF and followed up in a tertiary care center were included in this study. Seven (1.8%) patients were diagnosed with TB, three had extrapulmonary TB. There was no significant difference in age, gender, smoking rate, comorbidities, leukocyte and lymphocyte counts, hemoglobin, creatinine, AST, ALT, protein levels and tuberculin reaction size between patients with and without TB. 289 patients (76%) had received INH prophylaxis, including 43 patients who were tuberculin-negative. Besides,12 tuberculin-positive patients had not received any INH prophylaxis and 30 patients had anti-TNF use prior to INH prophylaxis. None of these patients had TB in the follow-up period. All seven patients who developed TB had completed 9-month INH treatment, including one patient who was tuberculin-negative. The time from the completion of INH treatment to the diagnosis of TB ranged from 6 to 110 months. None had any history of contact with TB during this period. INH treatment was associated with hepatotoxicity in 49 patients (17%), but all resolved without any need to stop INH. This study showed that patients on anti-TNF treatment had a high rate of TB despite INH prophylaxis, but no risk factor for TB development could be identified. Mild hepatotoxicity frequently develops during LTBI treatment.