Risk stratification for cardiac surgery: Comparison in a Hong Kong population

Abstract

Aim: Risk stratification is an important tool in preoperative decision‐making, counseling, informed consent and quality improvement. The European System for Cardiac Operative Risk Evaluation (logistic EuroSCORE) and EuroSCORE II were designed for the assessment of surgical risk. However, there are significant geographical and demographic differences between European and Hong Kong patients. The Queen Mary Hospital (QMH) risk score is a risk model designed to predict in‐hospital mortality for patients undergoing coronary artery bypass grafting (CABG) and valve surgery based on local data. In the present study, we compared the precision and clinical performance of the three scoring systems.

Patients and Methods: Data were collected prospectively from patients undergoing CABG and valve surgery between 2010 and 2015 in a single institution (n = 1693) in Hong Kong. Patients <18 years old and who had undergone congenital/aortic surgery were excluded. The receiver–operator curve (ROC) analysis was used to determine the discriminative ability of each score. Calibration was tested with the Hosmer–Lemeshow (HL) goodness‐of‐fit test.

Results: Observed mortality was 49/1639 (2.89 per cent). The predicted mortality rates were logistic EuroSCORE 9.23 per cent [95 per cent confidence interval (CI): 8.65–9.78 per cent], EuroSCORE II 3.87 per cent (95 per cent CI: 3.58–4.14) and QMH risk score 4.20 per cent (95 per cent CI: 4.04–4.33). The area under the ROC analysis revealed 0.849 (95 per cent CI: 0.804–0.895) for the logistic EuroSCORE, 0.87 (95 per cent CI: 0.826–0.913) for the EuroSCORE II and 0.841 (95 per cent CI: 0.788–0.895) for QMH risk score. The HL goodness‐of‐fit test showed that the QMH risk score was a good fit (P = 0.207); however, the logistic EuroSCORE (P = 0.003) and EuroSCORE II (P = 0.003) showed a poor fit.

Conclusions: All three scoring systems can be applied to a Chinese population with excellent risk prediction. The QMH risk score has a role in accurately predicting mortality rates in a Hong Kong population.