Comparative vascular audit using the POSSUM scoring system

Comparative audit using overall mortality and morbidity figures can be misleading as they do not take into account variations in surgical procedure and patient fitness. To examine these effects we have compared vascular surgery in two differing hospitals, during a similar 9-month period, using the POSSUM scoring system. In one unit, 255 patients underwent vascular surgery with an operative mortality of 9.4%, and morbidity of 37.3%. In the other unit, 89 patients underwent vascular procedures with an operative mortality of 20.2% and morbidity of 47.2%. At first sight there appear to be significant differences in operative outcome between the two units. However, analysis using the POSSUM system predicts a mortality rate of 10.2% for unit A and 20.2% for unit B (morbidity rates of 38.4% for unit A and 50.6% for unit B). Receiver operating curve (ROC) analysis demonstrated no significant difference between the two units (see Table III). POSSUM analysis may be of use in comparative audit.