External validation of the Glasgow Aneurysm Score to predict outcome in elective open abdominal aortic aneurysm repair

Abstract

Selecting patients based on their risk profiles could improve the outcome after elective surgery of an abdominal aortic aneurysm (AAA). The Glasgow Aneurysm Score (GAS) is a scoring system developed to determine such risk profiles. In other settings, the GAS has proved to have a predictive value for the postoperative outcome. The aim of this study was to investigate whether the GAS was also valid for the patients in our hospital and to examine risk factors with a possible predictive value for postoperative mortality and morbidity. We performed a retrospective cohort study in a university hospital. The medical records of 229 patients who underwent open elective repair for an AAA in the period 1994 to 2003 were retrospectively analyzed to assess the GAS and to determine which of the examined risk factors had a predictive value for the prognosis. Five patients (2.2%) died after surgery and 30 (13.1%) had a major complication. The GAS was predictive for postoperative death (P = .021; sensitivity, 1.00; 95% confidence interval [CI], 0.52 to 1.00; specificity, 0.67; 95% CI, 0.61 to 0.73) and also for major morbidity (P = .029; sensitivity, 0.63; 95% CI, 0.46 to 0.78; specificity, 0.70; 95% CI, 0.64 to 0.76). The positive predictive value (mortality, 0.06; morbidity, 0.24) and the positive likelihood ratio (mortality, 3.07; morbidity, 2.14) were low, however. The best cutoff value for the GAS was determined at 77. All the deceased patients (100%) and 63.3% of those who had a major complication had a risk score of >or=77. Of all examined risk factors, suprarenal clamping during surgery was predictive of in-hospital mortality (8.3%, P = .017). For major morbidity, three risk factors, all of which are components of the GAS, were predictive: age (P = .046), cardiac disease (P = .032), and renal disease (P = .041). The Glasgow Aneurysm Score has a predictive value for outcome after open elective AAA repair. Because of its relatively low positive predictive value for death and major morbidity, the GAS is of limited value in clinical decision-making for the individual high-risk patient. In some particular cases, however, the GAS can be a useful tool, especially for low-risk patients because it has good negative predictive value for this group. Suprarenal clamping was found to be a risk factor for postoperative death.