The Cardiac Anaesthesia Risk Evaluation (CARE) Score

Abstract

Introduction The multifactorial risk indices proposed to predict outcome after cardiac surgery [1-3] are complex and thus, unused by most centers. It has been shown that clinical judgement [4] and a few clinical variables [5] can provide a large amount of prognostic information in cardiac surgery. Therefore we hypothesized that a simple ordinal scale based on clinical judgement and a few risk factors, could easily be used by clinicians and yet, have acceptable accuracy in predicting mortality and length of stay (LOS) in hospital after cardiac surgery. Methods This is a prospective study of all adult patients undergoing a cardiac procedure, excluding heart transplant, in our institution between Nov. 12, 1996 and Sept. 29, 1997. Considering that acuteness of the procedure, surgical difficulty-complexity and unstable comorbid conditions are among the most important risk factors in cardiac surgery, [1-3] we developed the CARE score as 5 classes of elective patients and 3 classes of emergency cases: I. Patient with stable cardiac disease and no other medical problem. An uncomplicated surgery is expected. II. Patient with stable cardiac disease and one or more controlled medical problems. An uncomplicated surgery is expected. III. Patient with uncontrolled medical problem(s), including cardiac, OR patient in whom a surgical difficulty is expected. IV. Patient with uncontrolled medical problem(s), including cardiac, AND in whom a surgical difficulty is expected. V. Patient with chronic or advanced cardiac disease for whom cardiac surgery is undertaken as a last hope to save or improve life. E. Emergency: immediate surgical cases; applicable to classes III, IV and V only. The day of surgery, each patient was given a CARE score by one of the 8 attending anesthetists. Within 48 hours of surgery, this original CARE score was revised by a research assistant and one investigator (JYD) who corrected the score when they disagreed. The clinicians' ability in using the CARE score was assessed by measuring the Kendall's coefficient of concordance and the true concordance between the original and the corrected scores. Both scores were tested to see how they predict mortality and postoperative LOS in hospital >or=to 7, 14, 21 and 28 days. The accuracy of the original and revised CARE scores in the prediction of those variables was analyzed by building receiver operating characteristic (ROC) curves. An area >or=to 0.70 under the ROC curve determined the usefulness of the scores as outcome predictors. Results 1322 cardiac surgical patients were studied. There were 39 deaths (2.95%). The mean +/- SD postoperative LOS in hospital was 8.4 +/- 9.6 days (median of 6 days). The concordance between the original and revised scores was 88% (concordance coefficient = 0.9). Both scores gave a 0.75 area under the ROC curve for mortality and 0.72 for postoperative LOS in hospital. Discussion Clinicians use the CARE score reliably and consistently. The ability of the CARE score to predict mortality and prolonged LOS in hospital, a correlate of morbidity, compares with that of more complex multifactorial risk indices. [1-3] The CARE score is a simple, useful and meaningful tool which can easily be introduced in the practice of cardiac anaesthesia.