Figure 27-12 The observed morbidity after coronary artery bypass surgery versus the morbidity predicted by a clinical severity scoring system that evaluated various pertinent preoperative conditions. Morbidity was lower than the predicted 99.4% confidence interval at scores 2, 5, 6, and 7 to 9. The model may not be validated prospectively because of changes in clinical management that could result in complications. The vertical lines at top of the bars indicate confidence intervals. (Redrawn from Higgins TL, Estafanous FG, Loop FD, et al: Stratification of morbidity and mortality outcome by preoperative risk factors in coronary artery bypass patients. A clinical severity score. JAMA 267:2344, 1992.)