Do Physicians Remember Cases? Implications for Longitudinal Designs in Medical Research and Competency Assessment.

Background: In pathology and other specialties of diagnostic medicine, longitudinal studies and competency assessments often involve physicians interpreting the same images multiple times. In these designs, a washout period is used to reduce the chances that later interpretations are influenced by prior exposure. Objective/s: The present study examines whether a washout period between 9-39 months is sufficient to prevent three effects of prior exposure when pathologists review digital breast tissue biopsies and render diagnostic decisions: faster case review durations, higher confidence, and lower perceived difficulty. Methods: In a longitudinal breast pathology study, 48 resident pathologists reviewed a mix of five novel and five repeated digital whole slide images during Phase 2, occurring 9-39 months after an initial Phase 1 review. Importantly, cases that were repeated for some participants in Phase 2 were novel for other participants in Phase 2. We statistically tested for differences in participants' case review duration, self-reported confidence, and self-reported difficulty in Phase 2 based on whether the case was novel or repeated. Results: No statistically significant difference in review time, confidence, or difficulty as a function of whether the case was repeated or novel in a Phase 2 review occurring 9-39 months after initial viewing; this same result was found in a subset of participants with a shorter (9-14-month) washout. Conclusion: These results provide evidence to support the efficacy of at least a 9-month washout period in the design of longitudinal medical imaging and informatics studies to ensure no detectable effect of initial exposure on participant's subsequent case review.