Subjective versus statistical model assessment of mortality risk in open heart surgical procedures

Background. The aim of this study was to compare the predictive accuracy fo r open heart surgical mortality between a statistical model based on collec tion of clinical data and surgeons' subjective risk assessment. Methods. Predictive discrimination of both risk assessments (surgeons' and model) was compared through the area under the receiver operating character istic curve. Logistic regression analysis was used to assess the relation b etween surgeons' and model predictions to actual outcomes. Calibration of t he subjective estimates was evaluated with a chi(2) test. Results. Overall, the area under the receiver operating characteristic curv e was 0.76 for the statistical model and 0.70 for the subjective assessment . Logistic regression analysis showed that the statistical model remained s ignificant after accounting for the subjective assessment. Calibration of s ubjective mortality predictions was poor. Conclusions. Surgeons' risk assessment tends to cluster in the middle range s of risk. Subjective assessment seems accurate in identifying the two extr emes of risk but is inaccurate for intermediate risk levels. A multivariate statistical model improves the accuracy of subjective predictions. (Ann Th orac Surg 1999;67:635-40) (C) 1999 by The Society of Thoracic Surgeons.