Comparison of EuroSCORE II, Original EuroSCORE, and The Society of Thoracic Surgeons Risk Score in Cardiac Surgery Patients

Background The European System for Cardiac Operative Risk Evaluation (EuroSCORE) II was developed to reflect a more current dataset and evidence-based improvements in cardiac surgery. In the United States, The Society of Thoracic Surgeons (STS) risk score is more accepted owing to relatively high predictive value despite less user friendliness and inapplicability to some cardiac surgeries. We compared the precision of EuroSCORE II with EuroSCORE I and the STS risk score for operative mortality. Methods Data were collected prospectively for all cardiac surgery patients at a single center since 2001 (N = 11,788). A secondary analysis for patients with cardiac surgery not accommodated by the STS model compared only EuroSCORE II and I (N = 5,880). Receiver-operating characteristic analyses were performed for operative mortality to determine the discriminative ability for each score. Results Observed operative mortality was 1.8%. Mean predicted mortality for STS risk score, EuroSCORE II, and EuroSCORE I was 2.7%, 3.3%, and 7.8%, respectively. The discriminative ability for operative mortality by area under the curve for EuroSCORE II, EuroSCORE I, and STS risk score was 0.844, 0.819, and 0.846, respectively. In secondary analyses comparing EuroSCORE II with EuroSCORE I, risk scores were correlated (r_s = 0.83, p < 0.001). However, for operative mortality (observed, 4%), EuroSCORE II had better absolute prediction and discriminative ability (expected, 5.8%; area under the curve 0.754) than EuroSCORE I (expected, 12.5%; area under the curve 0.688). Conclusions EuroSCORE II had better predictive discrimination for operative mortality than EuroSCORE I, which greatly overestimated this risk. EuroSCORE II fared well compared with the STS risk score. The inclusive nature of EuroSCORE II for numerous procedures provides more flexibility than the STS score for complex procedures. EuroSCORE II should be considered for calculating risk score for complex cardiac surgical patients.