Rates of latent and active tuberculosis in BGC vaccinated, immunosuppressed Crohn's disease patients form Bulgaria before and during anti-tumor necrosis factor therapy.

Objective: Although the use of anti-tumor necrosis factor-alpha (anti-TNF-α) agents is highly effective in achieving and maintaining remission in patients with moderate-to-severe IBD, they place the patient at increased risk of developing opportunistic infections, including new cases of tuberculosis infection (TBI) and/or reactivation of latent tuberculosis infection (LTBI). Our study aims to determine the incidence of TBI [active tuberculosis (ATBI) and LTBI] among patients with Crohn's disease (CD) receiving anti-TNF-α therapy.

Patients And Methods: We performed a retrospective analysis of consecutive CD patients undergoing anti-TNF-α (infliximab, adalimumab) treatment for a minimum of 6 months, in the period between June 2010 and December 2019, followed-up at a reference IBD center. All patients were HIV negative, and BCG vaccinated. In all patients, ATBI was excluded and all were tested for LTBI prior to initiating a biological treatment.

Results: Before starting the biological treatment, we established LTBI in 11/109 (10.1%): 8/11 (72.7%) patients were TST positive, 2/11 (18.2%) were IGRA positive and TST negative, 1/11 (9.1%) were both IGRA and TST positive. In patients undergoing biological therapy with previous negative screening test for tuberculosis, a total of 16/74 (21.6%) patients were newly diagnosed with LTBI. The median induration (not erythema) diameter of TST is 8 (IQR 5-17) mm. Active pulmonary tuberculosis infection, developed in 3/74 (4.1%) patients. One patient developed ATBI on the background of chemoprophylaxis with INH for LTBI.

Conclusions: Specialists should thoroughly analyse all patient clinical data, chest X-ray results, epidemiological and BCG status, as well as perform a LTBI screening before initiating immunosuppressive and/or biological treatment. IBD patients have a higher risk of developing TBI in the first 12 months.