Risk of new-onset inflammatory bowel disease among patients with acne vulgaris exposed to isotretinoin

Background: Data on the risk of inflammatory bowel disease (IBD) among isotretinoin-exposed patients with acne vulgaris (AV) is controversial. Objective: To compare IBD risk in isotretinoin-exposed and unexposed patients with AV. Methods: Retrospective cohort analysis of patients with AV with and without isotretinoin exposure identified using electronic health records. Primary outcomes were 6-month and 1-year IBD incidence. Results: The crude 6-month IBD incidence was 0.08% (21/27,230) among isotretinoin-exposed patients with AV compared to 0.04% (254/631,089) among those unexposed. The crude 1-year IBD incidence was 0.10% (28/27,230) among isotretinoin exposed patients with AV and 0.08% (477/631,089) among those unexposed. The odds of developing IBD within 6 months were 87% higher among isotretinoin-exposed patients with AV compared to those unexposed (adjusted odds ratio, 1.87; 95% confidence interval [CI], 1.20-2.93), although the absolute difference was small (risk difference, 2.6 more cases per 10,000 patients; 95% CI, 0.7-4.5). There was no significant difference in the odds of developing IBD at 1 year between isotretinoin-exposed and unexposed patients with AV (adjusted odds ratio, 1.40; 95% CI, 0.95-2.05). Limitations: Isotretinoin-exposed patients may be more likely to have IBD detected by a health care provider. Conclusions: IBD incidence among isotretinoin-exposed patients with AV is very low, and the risk appears similar to that for unexposed patients with AV.