Risk interval analysis of emergency room visits following colonoscopy in patients with inflammatory bowel disease

Background and aims: Prior studies suggest that colonoscopy may exacerbate inflammatory bowel disease (IBD) symptoms. Thus, our study aimed to determine risk of emergency room (ER) visits associated with colonoscopy among IBD patients and evaluate potential modifiers of this risk. Methods: The study population included IBD patients in the Multi-Payer Claims Database who were >20 years old and had a colonoscopy from 2007–2010. We used a self-controlled risk interval design and mixed-effects Poisson regression models to calculate risk ratios (RR) and 95% confidence intervals (CI) comparing the incidence of ER visits in the 1–4 weeks following colonoscopy (risk interval) to the incidence of ER visits in the 7–10 weeks after colonoscopy (control interval). We also conducted stratified analyses by patient characteristics, bowel preparation type, and medication. Results: There were 212,205 IBD patients with at least 1 colonoscopy from 2007–2010, and 3,699 had an ER visit during the risk and/or control interval. The risk of an ER visit was higher in the 4-week risk interval following colonoscopy compared to the control interval (RR = 1.24; 95% CI: 1.17–1.32). The effect was strongest in those