Set up and validation of Chinese Risk Stratification System for Coronary Artery Bypass Grafting

Abstract

Objective Our study aims to evaluate the performance of Chinese risk stratification system for coronary artery bypass grafting (CABG) in the prediction of in-hospital mortality and major postoperative complications after CABG. Methods Clinical information of 9564 consecutive CABG patients was collected in Chinese Coronary Artery Bypass Grafting Registry which recruited 43 centers over China between 2007 and 2008. Sino System for Coronary Operative Risk Evaluation ( SinoSCORE) was developed using the logistic regression model. The SinoSCORE model was designed to predict in-hospital mortality among patients undergoing coronary artery bypass surgery. The scoring system finally identified 11 risk factors including age over 65, preoperative NYHA stage, chronic renal failure, chronic obstructive pulmonary disease, etc. Cut-off point was defined for SinoSCORE model to distinguish low( SinoSCORE: ≤ 1 ), moderate( SinoSCORE :2 -5 ) and high risk groups(≥6).AUC statistic (receiver operating characteristic curve) was used to test discrimination of SinoSCORE model and we assessed calibration of this model by the Hosmer-Lemeshow goodness-of-fit statistic. The above-mentioned results were compared with the European Risk System in Cardiac Operations (EuroSCORE). And we also assessed the applicability of SinoSCORE model in the prediction of in-hospital mortality among the three different risk groups by comparing the 95% confidence interval (CI) between the morbidity observed with that expected. Results SinoSCORE model showed good performance ( HL P ＞ 0. 05, AUC ＞ 0. 70 ) in the prediction of in-hospital mortality and postoperative complications. Of our study population, calibration by Hosmer-Lemeshow (HL) test for in-hospital mortality was P=0.70, discrimination by area under ROC (AUC) was 0.80. And for major postoperative complications, the risk model SinoSCORE model still turned out good including the following: stroke ( HL P = 0. 43, AUC = 0. 76, renal failure ( HL P = 0. 70, AUC = 0. 72 ), prolonged ventilation ( HL P = 0. 18, AUC = 0.70 ),multiple organ failure( HL P =0.49 ,AUC =0.79). By comparison with EuroSCORE model, SinoSCORE model proved better prediction ability in both the discrimination and calibration based on our research crowd. And during the different danger degree of patients, mortality observations 95% CI and estimated values of 95% CI were very good overlap, which indicated that this model for the three different risk groups are applicable. Conclusion SinoSCORE model is based on the newest clinical date of Chinese patients undergoing CABG. SinoSCORE can be used to predict not only in-hospital mortality, for which it was originally designed, but also postoperative complications. SinoSCORE proved better performance than the EuroSCORE model in Chinese CABG patients and is more suitable for? application? among? domestic cardiac surgery? physicians. Key words: Coronary artery bypass; Risk assessment; Postoperative complication; Risk factors sinoSCORE