Validation of the preoperative score to predict postoperative mortality (POSPOM) in patients undergoing major emergency abdominal surgery

Purpose Patients undergoing major emergency abdominal surgery have a high mortality rate. Preoperative risk prediction tools of in-hospital mortality could assist clinical identification of patients at increased risk and thereby aid clinical decision-making and postoperative pathways. The aim of this study was to validate the preoperative score to predict mortality (POSPOM) in a population of patients undergoing major emergency abdominal surgery. Methods POSPOM was investigated in a retrospectively collected cohort of patients undergoing major emergency abdominal surgery at a Danish University Hospital from 2010 to 2016. Predicted in-hospital mortality by POSPOM was compared to observed in-hospital mortality. Calibration was assessed by Hosmer–Lemeshow goodness-of-fit and calibration plot. Discrimination was assessed by area under the receiver operating characteristic curve and accuracy was assessed with Brier score. Results The study included 979 patients (513 females) with a median age of 64 (IQR 55–77) years. The majority of patients underwent open surgery (94.5%). The observed in-hospital mortality rate was 10.9%. The estimated mean in-hospital mortality rate by POSPOM was 6.7%. POSPOM showed a good discrimination [AUC 0.82 (95% CI 0.78–0.85)] and an excellent accuracy [Brier score 0.09 (95% CI 0.07–0.10)]. However, a poor calibration was found ( p < 0.01) as POSPOM underestimated in-hospital mortality. Conclusions POSPOM is not an ideal prediction model for in-hospital mortality in patients undergoing major emergency abdominal surgery due a poor calibration.