The relationship between predicted and actual cardiac surgical mortality: impact of risk grouping and individual surgeons

Objective: To study the relationship between predicted and actual mortality in a cardiac surgical practice and to determine whether there is a consist ent relationship across risk groups and surgeons. Methods: Risk information (Parsonnet score) was prospectively collected for 6213 consecutive adult p atients undergoing cardiac surgery at one institution. The relationship bet ween predicted mortality and actual mortality was analysed by risk group fo r all patients and For individual surgeons' practices. Results: Predicted m ortality was 10.2%. Actual mortality was 4.2%, giving a mortality ratio of 41% of predicted. This ratio was not consistent across the five major risk groups, ranging from 32% in moderate risk to 67% in very low risk patients. When analysed by individual surgical practices, the results were even more disparate, with a mortality index range between 0% for one surgeon's low r isk patients to 150% for another surgeon's very low risk patients. Conclusi on: The relationship between predicted and actual mortality at one institut ion may vary across the risk spectrum and between surgeons. This should be taken into account in preoperative risk assessment and informed patient con sent. Individual surgeons may have strengths and weaknesses which are relat ed to preoperative risk stratification. (C) 2001 Elsevier Science B.V. All rights reserved.