Background & aims: The primary aim of this study was to determine the incidence of active tuberculosis in an inflammatory bowel disease population compared with the general population before the availability of infliximab.
Methods: We performed a retrospective cohort study with the General Practice Research Database from January 1988-October 1997. Ulcerative colitis and Crohn's disease subjects with a minimum of 1 year of follow-up were matched to randomly selected subjects from the remaining population on year of birth (+/-5 years), sex, and primary care practice at ratio of 1:4. Active tuberculosis was determined by tuberculosis diagnostic codes. The incidence of active tuberculosis in the inflammatory bowel disease population and the relative risk for active tuberculosis in inflammatory bowel disease population compared with the general population were calculated. Multivariate logistic regression analysis was performed to adjust for confounders.
Results: There were 16,213 inflammatory bowel disease subjects and 66,512 control subjects. The annual incidence of active tuberculosis was 20/100,000 in inflammatory bowel disease subjects compared with 9/100,000 in control subjects, yielding an unadjusted relative risk for active tuberculosis of 2.36 (95% confidence interval, 1.17-4.74). Adjusting for confounders, corticosteroid use and smoking, the odds ratio of inflammatory bowel disease for active tuberculosis was 1.88 (95% confidence interval, 0.68-5.20).
Conclusions: During the pre-infliximab era, inflammatory bowel disease subjects appeared to be at higher risk for active tuberculosis than the general population, with immunosuppressant medications likely the main reason for this increased risk.