Safety of Continuing Single‐Agent Antithrombotic Therapy During Emergency Cholecystectomy for Acute Cholecystitis: An Overlap‐Weighted Propensity Score Analysis With the Hiroshima Surgical Study Group of Clinical Oncology ( HiSCO )

BACKGROUND/PURPOSE: Optimal perioperative antithrombotic therapy (ATT) management during emergency cholecystectomy for acute cholecystitis remains controversial. We examined whether continuing single-agent ATT is associated with hemorrhagic risk compared with no ATT. METHODS: This retrospective cohort study included 1018 patients (826 without ATT, 192 continued on single-agent ATT) at seven institutions (2020-2023). Propensity score overlap weighting balanced 12 baseline covariates. The primary outcome was intraoperative blood loss > 100 mL; risk ratios and 95% confidence intervals were estimated via modified Poisson regression, with upper confidence bound compared against a pre-specified risk ratio (1.5). RESULTS: The primary outcome occurred in 27.3% and 25.4% of the non-ATT and continued-ATT groups, respectively (risk ratio: 0.93, 95% confidence interval: 0.69-1.26). The upper bound of the confidence interval was within the pre-specified margin. No significant differences were observed in perioperative bleeding complications or hospital stay. Secondary outcomes, sensitivity analyses, and drug-specific subgroup analyses (including direct oral anticoagulants) yielded consistent results. CONCLUSIONS: Continuing single-agent ATT was comparable to no ATT regarding bleeding during cholecystectomy for acute cholecystitis. These findings suggest that emergency cholecystectomy can be performed without meaningful increases in hemorrhagic risk in patients for whom adequate preoperative ATT washout is not feasible.