S1495 Increased Risk of Immune Mediated Inflammatory Disorders and Worse Clinical Outcomes in Inflammatory Bowel Disease Patients With Concurrent Celiac Disease: Insights From a Propensity-Matched Nationwide Cohort Study

Introduction: Epidemiological studies have shown patients with celiac disease (CeD) more likely to develop inflammatory bowel disease (IBD), and vice versa, suggesting they may share common genetic and immune-related causes. The prevalence of immune mediated inflammatory disorders (IMID) in patients with IBD and CeD and the impact of CeD on clinical outcomes of IBD remain unknown. We aim to investigate the prevalence of IMID and outcomes of IBD in subjects with concurrent IBD and CeD using data from a large retrospective database. Methods: This large retrospective cohort study included adult patients with overlapping CeD and IBD, as well as those with IBD without CeD from the U.S. Collaborative Network in the TriNetX database through May 22, 2025. A 1:1 propensity score (PS) matching was performed for 28 covariates including age, sex, race, tobacco use, thyroiditis, and IBD type between the 2 cohorts. Outcomes analyzed included risk difference assessment of IMID, IBD phenotype, patterns of IBD medication use, hospital admissions, and mortality. Results: After PS matching, there was a total of 8,589 patients in the overlapping IBD + CeD cohort, and 8,386 patients in the isolated IBD cohort. IBD + CeD subjects were found to have statistically significant increased risk difference (RD) and risk ratios (RR) for rheumatoid arthritis, primary sclerosing cholangitis, autoimmune hepatitis, hidradenitis suppurativa, and psoriasis. This group also had increased RDs and RRs for bowel obstruction, although significantly less fistulation than the IBD group. The IBD + CeD group had significantly increased RR and RD for receiving steroids, 5-aminosalicylic acids (5-ASA), immunomodulators, and biologic drugs; this effect was not seen with small-molecule drugs. Higher inflammatory markers were also noted in the IBD + CeD group. Furthermore, this group also had higher all-cause mortality and rates of lifetime inpatient and intensive care unit admissions. Conclusion: The prevalence of IMID is greater in subjects with overlapping IBD + CeD. The use of steroids, and escalation to immunomodulators and biologics is also more common in these subjects, suggesting a more severe disease course needing clinicians to be more vigilant to these findings in tailoring diagnosis and treatment plans.