RESUMO
Self-explanation while diagnosing clinical cases fosters medical students' diagnostic performance. In previous studies on self-explanation, students were free to self-explain any aspect of the case, and mostly clinical knowledge was used. Elaboration on knowledge of pathophysiological mechanisms of diseases has been largely unexplored in studies of strategies for teaching clinical reasoning. The purpose of this two-phase experiment was to investigate the effect of self-explanation of pathophysiology during practice with clinical cases on students' diagnostic performance. In the training phase, 39 4th-year medical students were randomly assigned to solve 6 criterion cases (3 of jaundice; 3 of chest pain), either self-explaining the pathophysiological mechanisms of the findings (n = 20) or without self-explaining (n = 19). One-week later, in the assessment phase, all students solved 6 new cases of the same syndromes. A repeated-measures analysis of variance on the mean diagnostic accuracy scores showed no significant main effects of study phase (p = 0.34) and experimental condition (p = 0.10) and no interaction effect (p = 0.42). A post hoc analysis found a significant interaction (p = 0.022) between study phase and syndrome type. Despite equal familiarity with jaundice and chest pain, the performance of the self-explanation group (but not of the non-self-explanation group) on jaundice cases significantly improved between training and assessment phases (p = 0.035) whereas no differences between phases emerged on chest pain cases. Self-explanation of pathophysiology did not improve students' diagnostic performance for all diseases. Apparently, the positive effect of this form of self-explanation on performance depends on the studied diseases sharing similar pathophysiological mechanisms, such as in the jaundice cases.