Quantitative evaluation of the diagnostic thinking process in medical students

目的：探讨医学生的诊断思维过程。受试者与方法：对224名医学生进行冠状动脉疾病前测概率分别为高、低、中三种临床情景的分析。从学生（直观估计）或文献（参考估计）中得出运动压力测试的测试特征、测试前和测试后每种情景的概率。使用基于直觉估计（贝叶斯估计）或参考估计（参考估计）的贝叶斯定理计算测试后概率。参考估计值与直觉估计值（参考误差）、贝叶斯估计值与直觉估计值（贝叶斯误差）之间的差异用于评估测试特征知识、估计测试前和测试后疾病概率的能力。对于参加短期课程的学生…更多的是对考试成绩的解释，课前和课后评估之间的变化也进行了研究。结果：对于胸痛情景，参考误差和贝叶斯误差与参考估计值有明显的高估偏差。课程结束后，预测概率和预测值的估计值在高预测环境下显著提高，但在低和中预测环境下的估计值没有显著提高。结论：医学生在中低预测概率设置下不能排除疾病，主要原因是对疾病概率的预测估计较差，不善于将贝叶斯定理应用于实际临床情况。这些诊断思维模式解释了医学生最终重复不必要的检查的原因，可能与传统的医学教育有关，即在生物医学模式的框架内侧重于获取基础科学/医学知识。目前提供的短期课程提高了排除而不排除排除的诊断能力。有必要制定一个精心设计的以排除疾病为目标的教育计划。少

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