Prevalence and Bidirectional Association Between Autoimmune Liver Disease and Inflammatory Bowel Disease: A Meta‐Analysis

ABSTRACT Background and Aims While the association between inflammatory bowel disease (IBD) and autoimmune liver disease (AILD) is well‐established, prevalence estimates vary considerably across studies. In this study, a meta‐analysis was performed to determine the pooled prevalence and characterize the bidirectional relationship between AILD and IBD. Methods A systematic search was conducted in PubMed, Embase, and the Cochrane Library to identify observational studies reporting the prevalence between IBD and AILD. Data were extracted for eligible studies, and pooled prevalence estimates were derived using random effects models. Subgroup analyses were performed based on IBD and AILD subtypes, gender, race, geographical region, extent of IBD, and publication year. Results Of the 9347 citations, 172 studies involving 1 550 966 participants were included. The pooled prevalence of IBD among AILD patients, based on 65 studies, was 32.05% (95% CI 22.83%–42.94%; I 2 = 100%, p < 0.001). Specifically, the prevalence of IBD in patients with primary sclerosing cholangitis (PSC), autoimmune hepatitis (AIH), and primary biliary cirrhosis (PBC) was 62.79% (95% CI 57.74%–67.57%), 3.54% (95% CI 2.08%–5.96%), and 1.99% (95% CI 1.05%–3.74%), respectively. The pooled prevalence of AILD among IBD patients, based on 109 studies, was 2.28% (95% CI 1.88%–2.76%; I 2 = 100%, p < 0.001). Prevalence of PSC, AIH, and PBC in IBD patients was 2.24% (95% CI 1.85%–2.70%), 0.59% (95% CI 0.24%–1.47%), and 0.32% (95% CI 0.09%–1.13%), respectively. Subgroup analyses revealed significant variations in prevalence associated with gender, race, IBD extent, geographic region, and publication year. Conclusion This study reveals a significant bidirectional association in the prevalence of AILD and IBD, supporting the gut–liver axis theory. Further research is needed to elucidate causal mechanisms.