The Prevalence of Various Autoimmune Comorbidities in Patients with Inflammatory Bowel Disease

<b>Introduction:</b> Patients with inflammatory bowel disease (IBD) are at increased risk of developing other autoimmune disorders due to possible shared genetic, environmental, and immunological mechanisms. While autoimmune diseases are frequently observed in patients with IBD, data quantifying their inpatient prevalence and their association with outcomes such as mortality remain limited. <b>Methods:</b> National Inpatient Sample (NIS) 2016-2020 and International Classification of Diseases 10th Version, Clinical Modification (ICD-10-CM) diagnosis codes were used to identify patients with IBD and autoimmune conditions. A multivariate logistic regression analysis to identify an association between various autoimmune diseases and various IBDs was performed. <b>Results:</b> The study population included 141,478,025 patients. An association was found between 24 autoimmune conditions and IBD. <b>Conclusions:</b> Our study identified autoimmune comorbidities that are more prevalent in IBD patients. We found that polymyositis, AIHA, ITP, and thrombotic microangiopathy are associated with a higher risk of in-hospital mortality. Psoriasis and hypothyroidism are associated with a lower risk of in-hospital mortality. Further studies are needed to explore the mechanisms responsible.