The benefits of using atypical presentations and rare diseases in problem-based learning in undergraduate medical education.

Background: The nature of student learning in problem-based learning (PBL) largely depends on the quality of the case scenarios presented to them. The effect of case scenarios with higher challenge degree, especially common disease with atypical symptoms (CDAS)- and rare disease (RD)-based case scenarios, on undergraduate medical students remains unclear. This study compared the impact of all scenarios pertaining to common disease with typical symptoms (CDTS) case scenarios, CDTS interspersed with CDAS case scenarios, and CDTS interspersed with RD case scenarios on perceptions of undergraduate students studying organ/system integration curriculum via PBL.

Methods: After finishing four CDTS case scenarios, 294 third-year medical students were randomly allocated into three groups: CDTS, CDAS and RD, studying via CDTS, CDAS and RD case scenarios, respectively. A questionnaire with 15 items was conducted to evaluate the students' perceptions. The students' responses were scored using a 4-point rating scale. The data were analysed using the Kruskal-Wallis test.

Results: Among the three PBL conditions, the ones with a higher degree of challenge were rated higher by the students, which included the quality of the case scenarios and the overall performances of the students. The CDAS and RD cases were more effective in developing students' self-directed learning skills, stimulating them to acquire more knowledge required for future work. The satisfaction percentage of RD case scenario sessions was higher.

Conclusions: Of all the three kinds of case scenarios, both CDTS interspersed with CDAS and RD case scenarios had more positive effects on the self-evaluated performance of students. Increasing the challenge and variety of case scenarios by the inclusion of CDAS and RD especially RD might be an effective stimulus in improving students' performance in PBL sessions.