Objectives: The aim of the present study was to evaluate the performance of three different preoperative risk models in the prediction of postoperative morbidity and mortality in coronary artery bypass (CAB) surgery.
Methods: Data on 1132 consecutive CAB patients were prospectively collected, including preoperative risk factors and postoperative morbidity and in-hospital mortality. The preoperative risk models CABDEAL, EuroSCORE and Cleveland model were used to predict morbidity and mortality. A C statistic (receiver operating characteristic (ROC) curve) was used to test the discrimination of these models.
Results: The area under the ROC curve for morbidity was 0.772 for the CABDEAL, 0.694 for the EuroSCORE and 0.686 for the Cleveland model. Major morbidity due to postoperative complications occurred in 268 patients (23.6%). The mortality rate was 3.4% (n=38 patients). The ROC curve areas for prediction of mortality were 0.711 for the CABDEAL, 0.826 for the EuroSCORE and 0.858 for the Cleveland model.
Conclusions: The CABDEAL model was initially developed for the prediction of major morbidity. Thus, it is not surprising that this model evinced the highest predictive value for increased morbidity in this database. Both the Cleveland and the EuroSCORE models were better predictive of mortality. These results have implications for the selection of risk indices for different purposes. The simple additive CABDEAL model can be used as a hand-held model for preoperative estimation of patients' risk of postoperative morbidity, while the EuroSCORE and Cleveland models are to be preferred for the prediction of mortality in a large patient sample.