Validation of European System for Cardiac Operative Risk Evaluation (EuroSCORE) in North American cardiac surgery

Objective: To assess the performance of the European System for Cardiac Operative Risk Evaluation (EuroSCORE) when applied in a North American cardiac surgical population. Methods: The simple additive EuroSCORE model was applied to predict operative mortality (in-hospital or 30-day) in 401 684 patients undergoing coronary or valve surgery in 1998 and 1999 as well as in 188 913 patients undergoing surgery in 1995 in the Society of Thoracic Surgeons (STS) database. Results: The proportion of isolated coronary artery bypass grafting (CABG) was greater in STS patients (84%) than in Europe (65%). STS patients were also older (mean age 65.3 versus 62.5), and had more diabetes (30 versus 17%) and prior cardiac surgery (11 versus 7%). Other comorbidity was also significantly more prevalent in STS patients. EuroSCORE predicted overall mortality was virtually identical to the observed mortality (1998/1999: predicted 3.994%, observed 3.992%; 1995: observed and predicted 4.156%). Predicted mortality also closely matched observed mortality across the risk groups. Discrimination was good to very good for the population overall and for isolated CABG in both time periods, with the area under the receiver operating characteristic curve between 0.75 and 0.78. Conclusion: Despite substantial demographic differences between Europe and North America, EuroSCORE performs very well in the STS database, and can be recommended as a simple, additive risk stratification system on both sides of the Atlantic.