Risk stratification in cardiac surgery: is it worthwhile?

Outcome analysis of many surgical procedures has become increasingly important to surgeons, institutions, and the public. Because there may be wide differences in case mix, outcomes must be evaluated in light of the patient's preoperative status. All relevant preoperative conditions must be identified and weighted, so that when risk factor scores are combined in some fashion, they will provide a single preoperative risk estimate for the individual patient, representing the likelihood of dying as a consequence of the operation. Comparing the mean risk adjusted score of a group of patients undergoing the same procedure with the observed mortality rate for the same group yields an index of the quality of care, provided all preoperative risk scores are calculated with reference to the same benchmark. We question the logic and wisdom of surgical outcome analysis because of the infinitely complex nature of biological and pathological processes, as well as the practical problems of reliable data collection. The assumption of true scientific accuracy may be illusory. Even though risk adjusted outcome analysis has merit in studying trends in therapy, it should be regarded with caution when used as a tool for evaluating quality of care. If publicized at all, the results should not be represented as "hard" scientific fact.