Preoperative risk assessment in cardiac surgery: comparison of predicted and observed results.

In the present climate of quality-assurance policies, rigorous requirements for informed consent, and a constantly changing patient population, a system of preoperative risk assignment and postoperative correlation was developed to monitor and evaluate surgical performance. Patients were categorized by operation, priority (emergent, urgent, elective), New York Heart Association Functional Class, and risk. Risk was assigned before operation using data from the Coronary Artery Surgery Study (CASS) and the recent literature. Data were collected by a full-time data manager and were stored and analyzed by computer. From January 1, 1984, to July 1, 1985, 1,303 patients underwent operation for acquired disease. This group included 913 patients undergoing isolated primary coronary artery bypass grafting (CABG). The comparison of predicted and observed results showed: (Table: see text). For patients undergoing isolated primary CABG, the elective group had an operative mortality of 0.6% (2/329); the urgent group, 1.1% (5/450); and the emergent group, 5.2% (7/134). Preoperative risk assignment is an effective method of quality assurance. Female sex and age older than 60 years, which predicted an operative mortality of 2 to 5% in the CASS study and other recent series, did not predict a similar risk in our series.