Isotretinoin and risk of inflammatory bowel disease: a French nationwide study.

Isotretinoin, a drug widely prescribed for severe acne, has been suspected to increase the risk of ulcerative colitis (UC), but data are conflicting. To further examine the association between isotretinoin use and risk for UC and Crohn's disease (CD), we conducted a large nationwide case-control study in France. We used information from the National Health Insurance system for all French people covered by the general scheme between 1 January 2008 and 31 December 2010, totaling over 50 million individuals (i.e., 76% of the whole French population). All incident claims for UC and CD and all medical drug reimbursements were automatically recorded in the database. For each case, four controls were matched on age, gender, year of enrollment, and follow-up duration. The association between isotretinoin use and UC or CD claim was estimated by conditional logistic regression. We included 7,593 cases of inflammatory bowel disease (IBD; 3,187 UC, 4,397 CD, and 9 indeterminate colitis) and 30,372 controls; among them, 26 cases (0.3%) (15 UC (0.5%) and 11 CD (0.3%)) and 140 controls (0.4%) were exposed to isotretinoin. Isotretinoin exposure was not associated with an increased risk for UC (odds ratio (OR)=1.36 (95% confidence intervals (CI): 0.76, 2.45)) but was associated with a decreased risk for CD (OR=0.45 (95% CI: 0.24, 0.85)), P value for homogeneity between UC and CD=0.001. Results were similar in analyses restricted to individuals below the age of 40 years, to cases with colonoscopy or intestinal surgery, or when adjusting for other acne treatments. In this population-based case-control study, isotretinoin use was not associated with increased UC risk but was associated with a decreased CD risk. This study provides reassuring data for people using isotretinoin.