摘要Background:Currently,there is a deficiency in a strong risk prediction framework for precisely evaluating the likelihood of severe postoperative complications in patients undergoing elective hepato-pancreato-biliary surgery subsequent to experiencing breakthrough infection of coronavirus disease 2019(COVID-19).This study aimed to find factors predicting postoperative complications and construct an innovative nomogram to pinpoint patients who were susceptible to developing severe complications following break-through infection of COVID-19 after undergoing elective hepato-pancreato-biliary surgery.Methods:This multicenter retrospective cohort study included consecutive patients who underwent elec-tive hepato-pancreato-biliary surgeries between January 3 and April 1,2023 from four hospitals in China.All of these patients had experienced breakthrough infection of COVID-19 prior to their surgeries.Addi-tionally,two groups of patients without preoperative COVID-19 infection were included as comparative controls.Surgical complications were meticulously documented and evaluated using the comprehensive complication index(CCI),which ranged from 0(uneventful course)to 100(death).A CCI value of 20.9 was identified as the threshold for defining severe complications.Results:Among 2636 patients who were included in this study,873 were included in the reference group 1,941 in the reference group Ⅱ,389 in the internal cohort,and 433 in the external validation cohort.Multivariate logistic regression analysis revealed that completing a full course of COVID-19 vaccination＞6 months before surgery,undergoing surgery within 4 weeks of diagnosis of COVID-19 breakthrough infection,operation duration of 4 h or longer,cancer-related surgery,and major surgical procedures were significantly linked to a CCI＞20.9.A nomogram model was constructed utilizing CCI＞20.9 in the training cohort[area under the curve(AUC):0.919,95％confidence interval(CI):0.881-0.957],the internal validation cohort(AUC:0.910,95％CI:0.847-0.973),and the external validation cohort(AUC:0.841,95％CI:0.799-0.883).The calibration curve for the probability of CCI＞20.9 demonstrated good agreement between the predictions made by the nomogram and the actual observations.Conclusions:The developed model holds significant potential in aiding clinicians with clinical decision-making and risk stratification for patients who have experienced breakthrough infection of COVID-19 prior to undergoing elective hepato-pancreato-biliary surgery.