The application of European system for cardiac operative risk evaluation II (EuroSCORE II) and Society of Thoracic Surgeons (STS) risk-score for risk stratification in Indian patients undergoing cardiac surgery

Aims and Objectives: To validate European system for cardiac operative risk evaluation II (EuroSCORE II) and Society of Thoracic Surgeons (STS) risk-score for predicting mortality and STS risk-score for predicting morbidity in Indian patients after cardiac surgery. Materials and Methods: EuroSCORE II and STS risk-scores were obtained pre-operatively for 498 consecutive patients. The patients were followed for mortality and various morbidities. The calibration of the scoring systems was assessed using Hosmer-Lemeshow test. The discriminative capacity was estimated by area under receiver operating characteristic (ROC) curves. Results: The mortality was 1.6%. For EuroSCORE II and STS risk-score C-statics of 5.43 and 6.11 were obtained indicating satisfactory model fit for both the scores. Area under ROC was 0.69 and 0.65 for EuroSCORE II and STS risk-score with P values of 0.068 and 0.15, respectively, indicating poor discriminatory power. Good fit and discrimination was obtained for renal failure, long-stay in hospital, prolonged ventilator support and deep sternal wound infection but the scores failed in predicting risk of reoperation and stroke. Mortality risk was correctly estimated in low (< 2%) and moderate (2-5%) risk patients, but over-estimated in high-risk (> 5%) patients by both scoring systems. Conclusions: EuroSCORE II and STS risk-scores have satisfactory calibration power in Indian patients but their discriminatory power is poor. Mortality risk was over-estimated by both the scoring systems in high-risk patients. The present study highlights the need for forming a national database and formulating risk stratification tools to provide better quality care to cardiac surgical patients in India.