Reduced Shannon index indicates lower alpha-diversity in the gut microbiota of patients with primary biliary cholangitisGut Microbiota Differences Linked to Primary Biliary Cholangitis

BackgroundPrimary biliary cholangitis (PBC) is a chronic autoimmune cholestatic liver disease. Increasing evidence suggests that gut microbiota dysbiosis may contribute to its pathogenesis and progression. However, existing studies are limited by small sample sizes, methodological inconsistency, and the lack of quantitative synthesis, resulting in insufficient consolidated evidence.ObjectiveThis systematic review and meta-analysis aimed to evaluate alterations in the gut microbiota of patients with PBC.MethodsPubMed, Web of Science, Embase, and the Cochrane Library were systematically searched from inception to January 23, 2026. Outcomes included alpha-diversity indices, beta diversity, and taxonomic alterations. Meta-analyses were performed using standardized mean differences (SMDs) with 95% confidence intervals (CIs). Sensitivity analysis, subgroup analysis, and meta-regression were conducted to explore potential sources of heterogeneity.ResultsOf 1,326 records screened, 10 studies involving 1,057 participants (607 patients with PBC and 450 controls) were included, and all studies had Newcastle–Ottawa Scale scores of at least 7. Compared with controls, patients with PBC had a significantly lower Shannon index (SMD = −0.72, 95% CI: −1.22 to −0.22, p