HOW DO SURGEONS PROBABILITY ESTIMATES OF OPERATIVE MORTALITY COMPARE WITH A DECISION-ANALYTIC MODEL

The aim of this study is to compare surgeons' estimates of operative m ortality of patients with an abdominal aneurysm (= dilation of the aor ta) with the operative mortality derived from a decision analytic mode l and to determine how surgeons use clinical information. Four experie nced surgeons are asked to estimate, among other things, the operative mortality of 137 patients. Results concerning the accuracy of surgeon s' estimates show that surgeons' average operative mortality estimates are quite accurate as compared to the calculated mortalities. The sta ndard deviations of surgeons' estimates are lower than the standard de viation of the model, however, indicating that the surgeons are not as good in distinguishing the high and low risk patients. Furthermore, s urgeons show substantial inconsistencies in the weighing of the clinic al information, and also differ from the model in how clinical informa tion is weighed. Finally, when comparing the operative mortalities of the patients who died and those who did not, the model shows a modest, but higher discrimination than the surgeons. Physicians' performance seems to be influenced by the difficulty of the task (i.e. the unpredi ctability of the event and the multidimensionality of the task). In or der to improve physicians' probability estimates, the calculations of the decision model can be used as learning tool.