Prospective Evaluation of In-hospital Mortality with the P-POSSUM Scoring System in Patients Undergoing Major Digestive Surgery

Background The P-POSSUM score, the most well known of predictive scores for postoperative mortality, requires validation for population and setting. Methods Validation methods included discrimination ( C -index statistic), observed:expected ( O : E ) ratio, calibration with the Hosmer-Lemeshow test, and subgroup analysis (emergency surgery, cancer, age, organs). The study included 3,881 multisite patients undergoing major digestive surgery in France. Results Discrimination via the receiver operating characteristic curve was good ( C -index = 0.87). The overall O : E ratio was 1 (95% confidence interval ([95 % CI]: 0.88–1.13), and therefore the quality of the surgical performance is within normal ranges. The O : E ratio, calculated by risk ranges, showed overestimation in the low risk range, especially in the 3 % to 6 % and 6 % to 10 % ranges. Calibration was poor ( p