Risk of incident Mycobacterium tuberculosis infection in patients with inflammatory bowel disease: a nationwide population-based study in South Korea.

BACKGROUND: The low incidence of Mycobacterium tuberculosis infection and lack of adequate controls have prevented researchers from estimating tuberculosis (TB) risk in inflammatory bowel disease (IBD) patients.

AIM: To evaluate the risk of incident TB among IBD patients.

METHODS: Using the 2011-2013 data of the South Korean National Health Insurance (NHI) system, we calculated the incidence rates (IRs), standardised incidence ratio (SIR) and number needed to screen (NNS) for incident TB in IBD patients compared to the general population in terms of subtype, age, gender and IBD medications.

RESULTS: The IR, SIR and NNS for TB in IBD patients were 223.9/100 000 person-years, 2.64 (2.30-3.01) and 446.6 (392.8-517.6), respectively. The TB IR in Crohn's disease (CD) patients was significantly higher than that in ulcerative colitis (UC) patients (340.1/100 000 person-years vs. 165.5/100 000 person-years, respectively; P < 0.001). The SIR and NNS for TB among CD patients were 4.00 (3.59-4.45) and 604.2 (506.1-749.6), respectively; those among UC patients were 1.95 (1.66-2.27) and 294.0 (246.9-363.4). The TB IRs in IBD patients did not differ significantly by age or gender (Ptrend  = 0.505 and P = 0.861, respectively). The TB IRs among IBD patients prescribed 5-ASA, corticosteroids, immunomodulators and anti-TNF-α were 143.5, 208.5, 284.6 and 554.1 per 100 000 person-years, respectively. Among IBD patients treated using anti-TNF-α, the TB IR was significantly higher than that among all IBD patients (P < 0.001); the SIR and NNS for TB were 6.53 (5.99-7.09) and 180.5 (144.6-240.1) respectively.

CONCLUSION: Clinicians should be aware of the increased risk of active tuberculosis in patients with IBD who are receiving anti-TNF-α therapy.