Association of attention-deficit/hyperactivity disorder and autism with inflammatory bowel disease activity.

OBJECTIVES: To estimate the effect of attention deficit hyperactivity disorder (ADHD) and autism on the disease activity of inflammatory bowel disease (IBD) in pediatric and young patients. METHODS: Patients diagnosed with IBD between the ages of 6 and 24 years were identified in Danish nationwide registries 1996-2022. Cumulative incidences for severe disease activity (defined as advanced therapies, oral corticosteroids, IBD-related surgery and hospitalization) were estimated and compared between patients with IBD with and without ADHD/autism. Cox regression analysis was used to calculate adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs) for each of the severe events. RESULTS: A total of 785 patients with IBD and ADHD/autism and 6729 patients with IBD only were included. ADHD and autism were associated with a higher cumulative incidence of severe disease activity (10-year cumulative incidence: 36.2% vs. 33.7%). When investigating each severe event, ADHD and autism were associated with a higher risk of receiving advanced IBD therapies (aHR: 1.2, 95% CI: 1.0-1.3). Patients with ulcerative colitis and ADHD/autism had a higher risk for colectomy (aHR: 1.4, 95% CI: 1.0-1.8), especially those diagnosed with IBD before 18 years of age (aHR: 1.7, 95% CI: 1.1-2.6). CONCLUSIONS: ADHD and autism were associated with more severe IBD disease activity in pediatric and young patients. Although mainly smaller effects were observed, the findings may inform targeted efforts for patients with ADHD/autism and IBD to reduce the likelihood of severe disease activity.