Scoring systems do not accurately predict outcome following abdominal aortic aneurysm repair

Background: Abdominal aortic aneurysm repair is associated with significant morbidity and mortality. This study aims to evaluate the efficiency of scoring systems in a group of patients undergoing abdominal aortic aneurysm repair. Methods: A prospective study of 152 patients undergoing aneurysm repair was conducted. Each patient was scored according to the Acute Physiology and Chronic Health Evaluation II, Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity and Simplified Acute Physiology Score II systems. The predicted mortality for each patient was calculated. chi(2) analysis was carried out to determine the accuracy of mortality predictions. Receiver-operator curves were drawn to compare scoring systems in terms of sensitivity and specificity. Results: In the elective aneurysm repair group, all scoring systems tended to overestimate mortality. Receiver-operator curves showed inaccuracies in identifying patients who were at high risk from surgery. In contrast, predicted mortalities underestimated the true death rate among the ruptured aneurysm group. Receiver-operator curves showed better efficiency of scoring systems in the ruptured aneurysm group than in the elective repair group. There was no significant correlation between predicted and observed mortalities in either group. Conclusion: In this study, all systems showed significant errors when predicting mortality. Therefore, although useful as an audit tool, scoring systems should not be used on an individual basis to guide treatment and assess prognosis after surgery.