It's the destination: diagnostic accuracy and reasoning

While multiple theories exist to explain the diagnostic process, there are few available assessments that reliably determine diagnostic competence in trainees. Most methods focus on aspects of the process of diagnostic reasoning, such as the relation between case features and diagnostic hypotheses. Inevitably, detailed elucidation of aspects of the process requires substantial time per case and limits the number of cases that can be examined given a limited testing time. Shifting assessment to the outcome of diagnostic reasoning, accuracy of the diagnosis, may serve as a reliable measure of diagnostic competence and would allow increased sampling across cases. The present study is a retrospective analysis of 7 large studies, conducted by 3 research teams, that all used a series of brief written cases to examine the outcome of diagnostic reasoning-the diagnosis. The studies involved over 600 clinicians ranging from final year medical students to practicing emergency physicians. For 4 studies with usable reliability data, reliability for a 2 h test ranged from .63 to .94. On average speeded tests were more reliable (.85 vs. .73).To achieve a reliability of .75 required an average test time of 1.11 h for speeded tests and 1.99 for unspeeded tests. The measure was shown to be positively correlated with both written knowledge tests and measures of problem solving derived from OSCE performance tests. This retrospective analysis provides evidence to support the implementation of outcome-based assessments of clinical reasoning.