Structured medical ethics education and professional identity formation during clinical internship: a multiphase mixed-methods study

Introduction Professional identity formation (PIF) is a central developmental task during clinical internship, when medical students transition from learners to future physicians in workplace-based clinical settings. Although medical ethics education is considered important for professional development, evidence regarding how structured ethics education influences PIF during this critical stage remains limited, and the mechanisms underlying identity development are not well understood. Methods This multiphase mixed-methods study, incorporating an explanatory sequential component, evaluated the effect of a theory-informed medical ethics education programme among 216 final-year undergraduate medical interns at a teaching hospital in China. Participants were allocated using stratified block randomisation. The intervention group received five 80-minute sessions over two weeks, totalling 400 minutes of instruction, whereas the control group continued routine internship training. PIF was assessed at baseline (T0) and follow-up (T1) using a 20-item, five-dimensional scale. Quantitative data were analysed using mixed-effects models and non-parametric tests. Sixteen interviews involving 13 unique participants were analysed thematically to explore potential explanations for the observed changes. Results Compared with the control group, the intervention group showed a significantly greater improvement in the overall PIF mean score (β = 0.488, 95% CI: 0.397–0.580; p < 0.001). Improvements were observed across all five dimensions, with relatively greater gains in professional cognition, ethical responsibility identification, and sense of group belonging. Exploratory moderation analyses suggested that estimated intervention effects varied according to prior ethics-related practice and baseline PIF level, with greater observable improvements among interns without prior ethics-related practice and those with lower baseline PIF levels. Qualitative findings further identified four interrelated mechanisms that may help explain the observed changes: cognitive reframing, practical support, emotional regulation, and value internalisation. Conclusions The findings suggest that structured medical ethics education during clinical internship may support short-term improvements in PIF scores and provide educational support for the transition from student to physician. The four mechanisms offer potential explanations for participants' experiences of change. Longer-term evaluation is needed to determine whether the observed improvements are sustained and translate into professional practice.