Daniel Mulder

Background Previous national registry studies have reported an increased risk of eating disorders in immune-mediated conditions (inflammatory bowel disease [IBD] and celiac disease). Our objective was to examine the association between immune-mediated GI diseases and incident eating disorders in Ontario. Methods This was a retrospective matched cohort study of individuals <50 years of age with a diagnosis of an immune-mediated GI disease between 2002 and 2020 (“cases”). Those with a pre-existing eating disorder were excluded. Cases (n=83,920) were matched with controls (n=167,776) based on birth year, sex, and region of residence. Incidence rate ratio and hazard ratio were estimated using Poisson regression model and adjusted Cox proportional models, respectively. Results Over the follow-up period (up to January 31, 2022), 161 cases and 160 controls were identified with eating disorders. The overall incidence rate ratio (95% CI, p-value) of eating disorders in immune-mediated GI disease was 1.99 (1.6–2.5, p<0.001). The adjusted hazard ratios for eating disorder in cases with immune-mediated GI diseases was 1.98 (1.6–2.5, p<0.001). In the pediatric group of incident cases (≤18 years of age), overall adjusted hazard ratio was 2.62 (1.9–3.7, p<0.001)) compared to 1.56 (1.02–2.4, p=0.041) for adults (>18 years of age). The largest hazard ratio of 4.11 (1.6–10.3, p=0.003) was observed for pediatric incident cases of ulcerative colitis. Conclusion IBD and celiac disease are associated with the development of eating disorders. The magnitude of the association was stronger in the pediatric age group, underscoring the need for early screening and detection.