BACKGROUND: Approximately 25% of individuals with inflammatory bowel disease (IBD) concurrently experience immune-mediated inflammatory diseases (IMIDs), while the overall prevalence of these conditions in the general population is 5-7%. Individuals with IBD and concurrent IMIDs tend to have a more aggressive disease profile. We aimed to assess the prevalence of coexisting autoimmune disorders among patients with IBD and their association with inflammatory bowel disease type. METHODS: In this cross-sectional study at a tertiary care center in Riyadh, Saudi Arabia, we examined 875 patients with IBD (530 with Crohn's disease and 345 with ulcerative colitis). Patient demographics, disease types, treatment modalities, and co-occurring autoimmune conditions were analyzed using statistical and regression analyses. RESULTS: Overall, 21.7%, 19.4%, and 25.2% of the patients had IMIDs, Crohn's disease, and ulcerative colitis, respectively. Patients with ulcerative colitis had higher rates of hepatic autoimmune conditions (9.6%) and endocrine autoimmune diseases (4.1% vs 1.3%
P = 0.010) than those with Crohn's disease (4.5%
P = 0.003). Regression analysis revealed significant associations between hepatic (P = 0.012) and endocrine autoimmune diseases (P = 0.018) with ulcerative colitis diagnosis, although the model's predictive accuracy was moderate (overall, 63%
specificity, 95%
sensitivity, 14%). CONCLUSIONS: Our study highlights the significant co-occurrence of autoimmune diseases with IBD, particularly the distinct autoimmune profiles of Crohn's disease and ulcerative colitis. Identifying the specific ulcerative colitis-associated autoimmune comorbidities could guide personalized therapeutic strategies and inform future research on the pathophysiological relationship between these conditions.