Latent tuberculosis screening tests and active tuberculosis infection rates in Turkish inflammatory bowel disease patients under anti-tumor necrosis factor therapy

BACKGROUND Tumor necrosis factor (TNF)-α inhibitors increase the risk of tuberculosis (TB). The objective of the present study was to determine the rate of active TB infection in inflammatory bowel disease (IBD) patients receiving anti-TNF therapy and to determine the results of their latent TB infection (LTBI) screening tests during the follow up. METHODS This is a retrospective observational study of IBD patients receiving anti-TNF therapy. Tuberculin skin test (TST), interferon-γ release assay (IGRA), and chest radiography were used to determine LTBI. Active TB infection rate during anti-TNF treatment was determined. RESULTS Seventy-six IBD patients (25 with ulcerative colitis, 51 with Crohn's disease; 53 male; mean age 42.0±12.4 years) were included. Forty-four (57.9%) patients received infliximab and 32 (42.1%) adalimumab. Their median duration of anti-TNF therapy was 15 months. Forty-five (59.2%) patients had LTBI and received isoniazid (INH) prophylaxis. During the follow-up period, active TB was identified in 3 (4.7%) patients who were not receiving INH prophylaxis. There was a moderate concordance between the TST and the IGRA (kappa coefficient 0.44, 95% CI 0.24-0.76). Patients with or without immunosuppressive therapy did not differ significantly with respect to TST (P=0.318) and IGRA (P=0.157). CONCLUSION IBD patients receiving anti-TNF therapy and prophylactic INH have a decreased risk of developing active TB infection. However, despite LTBI screening, the risk of developing active TB infection persists.