Prospective evaluation of 3 risk stratification scores in cardiac surgery

Background: The aim of the study was to evaluate 3 different risk stratification scores in cardiac surgery, based on the hospital results of 1299 patients. Methods: From June 1995 to December 1997, all patients (n = 1299) undergoing coronary artery bypass grafting (CABG) and/or heart valve surgery were prospectively enrolled. The postoperative in-hospital outcome (mortality, morbidity and length of hospital stay) was analysed in relation to three different risk stratification scores (Parsonnet, Higgins and French score). Results: The results of 1299 patients (mean age 62.8 +/- 10.2 years) were analysed. 10 patients died, accounting for a total mortality of 0.8 %. 13 patients (1 %) underwent cardiopulmonary resuscitation. In 25 patients (1.9%), perioperative myocardial infarction occurred. Performance of the 3 systems was assessed by evaluating discrimination with receiver operating characteristic (ROC) curves. The area under the ROC curve was 0.761 for Parsonnet, 0.786 for Higgins and 0.798 for French score. The French and the Higgins score showed an increase of in-hospital mortality, morbidity and length of stay in relation to increasing risk classes. Conclusion: For objective evaluation of the outcome in cardiac surgery, case-mix severity needs to be considered, which is reflected by preoperative risk stratification scores. In our study, all the 3 scores showed a high discrimination and are appropriate tools to assess mortality in cardiac surgery. Especially the French and the Higgins score (restricted to 5 groups), due to their simplicity, were useful to predict postoperative outcome in clinical routine.