Evaluation of surgical performance using V-POSSUM risk-adjusted mortality rates

Vascular-Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity (V-POSSUM) is a risk-adjusted scoring system for predicting 30-day mortality in patients undergoing vascular surgery. It can assess surgical performance by comparing predicted deaths with observed deaths. The aim of this analysis was to assess trends in surgical performance over time using risk-adjusted 30-day mortality as the primary outcome. Major vascular surgery procedures (n = 454) were prospectively scored for V-POSSUM between 1995 and 2006. Procedures were divided into 11 consecutive time bands. Observed and predicted deaths were compared using the logistic regression equation derived for V-POSSUM. The observed death rates decreased over time, as did the predicted number of deaths calculated from the V-POSSUM scores. The overall predicted mortality rate was 17.2% and the rate varied with the 12-month period, with a high of 23.9% and a low of 9.2%. The downward trend in the predicted rate shows that the patient risk factors have changed over time and that the risk of dying has declined by almost 50% (from 21.6 to 11.1%). There was a trend towards improved surgical performance over time, with a drop in the observed to predicted ratios of deaths. Observed and predicted deaths changed over the study periods. There was a trend towards improved performance compared with the risk-adjusted predicted mortality. V-POSSUM is a useful tool in the longitudinal assessment of performance in major vascular surgery.