OBJECTIVE: To construct a scoring system for the prediction of early
mortality in cardiac surgical patients in Europe on the basis of objective
risk factors. METHODS: The EuroSCORE database was divided into developmental
and validation subsets. In the former, risk factors deemed to be objective,
credible, obtainable and difficult to falsify were weighted on the basis of
regression analysis. An additive score of predicted mortality was
constructed. Its calibration and discrimination characteristics were
assessed in the validation 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 discrimination by area under ROC curve was 0.79. The
validation dataset had 1479 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. Patient-related factors were age over 60
(one per 5 years or part thereof), female (1), chronic pulmonary disease
(1), extracardiac arteriopathy (2), neurological dysfunction (2), previous
cardiac surgery (3), serum creatinine >200 micromol/l (2), active
endocarditis (3) and critical preoperative state (3). Cardiac factors were
unstable angina on intravenous nitrates (2), reduced left ventricular
ejection fraction (30-50%: 1, <30%: 3), recent (<90 days) myocardial
infarction (2) and pulmonary systolic pressure >60 mmHg (2).
Operation-related factors were emergency (2), other than isolated coronary
surgery (2), thoracic aorta surgery (3) and surgery for postinfarct septal
rupture (4). The scoring system was then applied to three risk groups. The
low risk group (EuroSCORE 1-2) had 4529 patients with 36 deaths (0.8%), 95%
confidence limits for observed mortality (0.56-1.10) and for expected
mortality (1.27-1.29). The medium risk group (EuroSCORE 3-5) had 5977
patients with 182 deaths (3%), observed mortality (2.62-3.51), predicted
(2.90-2.94). The high risk group (EuroSCORE 6 plus) had 4293 patients with
480 deaths (11.2%) observed mortality (10.25-12.16), predicted
(10.93-11.54). Overall, there were 698 deaths in 14,799 patients (4.7%),
observed mortality (4.37-5.06), predicted (4.72-4.95). CONCLUSION: EuroSCORE
is a simple, objective and up-to-date system for assessing heart surgery,
soundly based on one of the largest, most complete and accurate databases in
European cardiac surgical history. We recommend its widespread use.
