Validation of a preoperative risk index as a predictor of perioperative morbidity and hospital costs in coronary artery bypass graft surgery

Objective: To validate a previously developed model (CABDEAL) for predicting postoperative morbidity for coronary artery bypass graft (CABG) surgery patients using the New York State Statewide Planning and Research Cooperative System (SPARCS) database and to examine the effects of preoperative risk factors, postoperative complications, and death on costs of care for CABG surgery. Design: Retrospective database review. Setting: Governmental agency database of cardiac surgery. Participants: CABG surgery patients (n = 15,388). Interventions: A previously developed preoperative risk model (CABDEAL) was applied to all patients. Predicted length of hospital stay and costs were compared with actual length of stay and costs, using a charge-to-cost conversion formula. Measurements and Main Results: The CABDEAL model was moderately predictive of outcomes. The specificity was 64%, the sensitivity was 73.8%, and the receiver operating characteristic curve area was 0.728. Morbidity in the form of postoperative complications was recorded in 24.5% (3,770 patients), and the mortality rate was 3.4% (527 patients). The mean (± SD) total hospital cost was $28,408 ± 28,982, and the median cost was $21,644. Based on the linear regression model, an equation was developed for predicting total costs: Cost (in $) = 22,952 + (3,277 · [CABDEAL score]). Conclusion: The previously developed CABDEAL model was predictive of increased morbidity in the SPARCS database. Total hospital costs increased nearly linearly with increasing CABDEAL score. These results encourage the development of models for preoperative estimation of costs related to perioperative morbidity. Copyright 2002, Elsevier Science (USA). All rights reserved.