Quantitative evaluation of the diagnostic thinking process in medical students

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OBJECTIVE : To explore the diagnostic thinking process of medical studentsSUBJECTS AND METHODS : Two hundred twenty-four medical students were presented with three clinical scenarios corresponding to high, low, and intermediate pre-test probability of coronary artery disease. Estimates of test characteristics of exercise stress test, pre-test and post-test probability for each scenario were elicited from the students (Intuitive estimates) or from the literature (Reference estimates). Post-test probabilities were calculated using Bayes' theorem based upon the Intuitive estimates (Bayesian estimates) or upon the Reference estimates (Reference estimates). The differences between the Reference estimates and the Intuitive estimates (Reference error), and between Bayesian estimates and the Intuitive estimates (Bayesian error) were used for assessing knowledge of test characteristics, ability of estimating pretest and posttest probability of disease. For students who took a short course focus … More ing on interpretation of test performance, changes between pre- and post-course estimates were also studied.RESULTS : For chest pain scenario, the Reference and Bayesian error showed gross deviations toward overestimating from the reference estimates. The estimates of pretest probability and predictive value positive significantly improved in high pretest setting after the course, but the estimates in low- and intermediate- scenarios did not.CONCLUSIONS : Medical students could not rule out disease in low or intermediate pre-test probability settings, mainly because of poor pre-test estimates of disease probability and inaptitude in applying Bayes' theorem to real clinical situations. These diagnostic thinking patterns account for why medical students end up repeating unnecessary examinations and may be related to the traditional medical education, i.e., focusing on acquiring basic science/medical knowledge in the framework of biomedical model. The short course as currently offered improves diagnostic ability of ruling in but not ruling out. It is necessary to develop a well-designed educational program targeted on ruling out disease. Less