Preoperative risk evaluation scores are used prior to surgery to predict perioperative risks. They are also a useful tool to help clinicians communicate the risk–benefit balance of the procedure to patients. This review identifies and assesses the existing preoperative risk evaluation scores (also called prediction scores) of postoperative mortality in all types of surgery (emergency or scheduled) in an adult population.

We systematically identified studies using the MEDLINE, Ovid EMBASE and Cochrane databases and published studies reporting the development and validation of preoperative predictive scores of postoperative mortality. We assessed usability, the level of evidence of the studies performed for external validation, and the predictive accuracy of the scores identified. We found 26 scores described within 60 different reports. The most suitable scores with the highest validity identified for anaesthesia practice were the Preoperative Score to Predict Postoperative Mortality (POSPOM), the Universal ACS NSQIP surgical risk calculator (ACS-NSQUIP), the Clinical Frailty Scale (CFS) and the American Society of Anesthesiologists Physical Status (ASA-PS) classification system. While other scores identified in this review could also be endorsed, their level of validity and generalizability to the general surgical population should be carefully considered.