ABSTRACT
BACKGROUND: For risk stratifying patients undergoing coronary artery bypass graft (CABG), the Society of Thoracic Surgeons (STS) risk score and the European System for Cardiac Operative Risk Evaluation (EuroSCORE) are currently used. However, the superiority of one over the other in the context of Indian patients has not been assessed. The aim of this study was to compare these 2 scoring systems in Indian patients undergoing CABG. METHODOLOGY: This was a retrospective analysis of prospectively collected data between January 2015 and September 2020 of all patients undergoing CABG. Observed mortality in the cohort was compared with the predicted mortality using the STS and the EuroSCORE II. Sensitivity and specificity were calculated for both the scores. Receiver operating characteristic (ROC) curves were constructed for both the STS and the EuroSCORE II and area under the ROC curve (AUC) was calculated. RESULTS: A total of 4895 patients were included in the study. The overall observed mortality in the entire cohort was 74 (1.5%). The EuroSCORE II-predicted mortality was 1.9 ± 2.5 whereas the STS score-predicted mortality was 1.2 ± 1.8. The observed to predicted mortality ratio for EuroSCORE was 0.79 and 1.25 for the STS score. The discriminative ability for operative mortality of the STS score was 0.72 (0.71 to 0.74) and 0.713 for the EuroSCORE, suggesting satisfactory discriminatory power. There was no difference between the STS score and the EuroSCORE in terms of discriminatory power (p = 0.58) and a difference in the AUC being 0.01. The discriminatory power of the EuroSCORE and the STS score was best in the high-risk category. CONCLUSIONS: Both the EuroSCORE and the STS scores had satisfactory and similar discriminatory power. However, in the Indian population, while the EuroSCORE II overestimated mortality, the STS score underestimated it to a similar degree of error.
