Clinical experience did not reduce the variance in physicians' estimates of pretest probability in a cross-sectional survey

Background and Objectives: In light of the increasing popularity of the threshold approach in clinical decision-making, this study assesses the role of expertise in physicians' agreement in estimating the probability of disease in patients. Methods: A cross-sectional survey of physicians of different specialties, attending weekly staff meetings in four teaching hospitals in Jerusalem, Israel. An anonymous questionnaire describing three case scenarios of patients with chest pain was administered and participants were asked to estimate pretest probabilities of disease. Results: Eighty-six physicians (practicing cardiology, internal medicine, and family medicine, as well as general practitioners and internists) out of 125 approached (response rate 69%). The mean estimated probabilities were very similar for residents and specialists; however, the standard deviation was higher for specialists in all three cases: 20.7, 21.0, and 19.1 among specialists and 16.4, 20.5, and 14.9 among residents, respectively. Conclusion: This study, based on case scenarios, did not find that medical expertise improved agreement among doctors when estimating the probability of disease in patients - despite the common belief that senior physicians should have smaller interobserver differences in probability estimates. The wide variation observed calls into question the applicability of the threshold approach.