Prior Gastrointestinal Infection and Risk of Post‐ERCP Biliary Tract Infection in Patients With Choledocholithiasis: A Prospective Cohort Study

ABSTRACT Background Post‐ERCP biliary tract infection (PEBTI) poses significant risks, but the impact of prior gastrointestinal infection remains unclear. Methods This multicenter, prospective cohort study of choledocholithiasis patients undergoing elective ERCP evaluated PEBTI incidence over 1 month. Directed acyclic graphs (DAGs) were used to conceptualize the roles of measured variables in PEBTI susceptibility, and inverse probability of treatment weighting (IPTW) was applied to balance confounders. The association between prior gastrointestinal infection and PEBTI was evaluated using Cox regression. Sensitivity analyses were further performed with trimmed/stabilized IPTW and E‐value calculation. Results Among 1507 enrolled patients, 604 (40.0%) reported prior gastrointestinal infection. The cumulative incidence of PEBTI was 5.4% in patients with prior gastrointestinal infection compared to 4.2% in those without (unadjusted HR = 1.32; 95% CI: 0.83–2.10; p = 0.246). After IPTW adjustment, the hazard of PEBTI increased significantly (HR = 2.71, 95% CI: 1.24–5.92, p = 0.013), of which 20.3% was mediated by preoperative gastrointestinal colonization. Sensitivity analyses confirmed the robustness of this association (trimmed/stabilized IPTW HR = 2.89 and 2.67, p < 0.05). Conclusion Prior gastrointestinal infection independently elevates PEBTI risk. Findings highlight the need for tailored prophylactic strategies alongside current guidelines and mechanistic explorations to mitigate post‐ERCP infections.