European system for cardiac operative risk evaluation (EuroSCORE)

Objective: To construct a scaring system for the prediction of early mortal ity in cardiac surgical patients in Europe on the basis of objective risk f actors. Methods: The EuroSCORE database was divided into developmental and validation subsets. In the former, risk factors deemed to be objective, cre dible, obtainable and difficult to falsify were weighted on the basis of re gression analysis. An additive score of predicted mortality was constructed . Its calibration and discrimination characteristics were assessed in the V alidation dataset. Thresholds were defined to distinguish low, moderate and high risk groups. Results: The developmental dataset had 13 302 patients, calibration by Hosmer Lemeshow Chi square was (8) = 8.26 (P < 0.40) and dis crimination by area under ROC curve was 0.79. The validation dataset had 14 79 patients, calibration Chi square (10) = 7.5, P < 0.68 and the area under the ROC curve was 0.76. The scoring system identified three groups of risk factors with their weights (additive % predicted mortality) in brackets. P atient-related factors were age over 60 (one per 5 years or part thereof), female (1), chronic pulmonary disease (1), extracardiac arteriopathy (2), n eurological dysfunction (2), previous cardiac surgery (3), Serum creatinine >200 mu mol/l (2), active endocarditis (3) and critical preoperative state (3). Cardiac factors were unstable angina on intravenous nitrates (2), red uced left ventricular ejection fraction (30-50%: 1, <30%: 3), recent (<90 d ays) myocardial infarction (2) and pulmonary systolic pressure >60 mmHg (2) . Operation-related factors were emergency (2), other than isolated coronar y surgery (2), thoracic aorta surgery (3) and surgery for postinfarct septa l rupture (4). The scoring system was then applied to three risk groups. Th e low risk group (EuroSCORE 1-2) had 4529 patients with 36 deaths (0.8%), 9 5% confidence limits for observed mortality (0.56-1.10) and for expected mo rtality (1.27-1.29). The medium risk group (EuroSCORE 3-5) had 5977 patient s with 182 deaths (3%), observed mortality (2.62-3.51), predicted (2.90-2.9 4). The high risk group (EuroSCORE 6 plus) had 4293 patients with 480 death s (11.2%) observed mortality (10.25-12.16), predicted (10.93-11.54). Overal l, there were 698 deaths in 14 799 patients (4.7%), observed mortality (4.3 7-5.06), predicted (4.72-4.95). Conclusion: EuroSCORE is a simple, objectiv e and up-to-date system for assessing heart surgery, soundly based on one o f the largest, most complete and accurate databases in European cardiac sur gical history. We recommend its widespread use. (C) 1999 Elsevier Science B .V. All rights reserved.