Association of duration and timing of physicians’ early-career training with subsequent settlement in medically underserved areas in Japan: A nationwide cohort study

Exposure to medically underserved areas during early-career training has been proposed as a strategy to address physician maldistribution; however, evidence on the overall physician population and the role of exposure timing remains limited. Using nationwide longitudinal data, this retrospective cohort study examined how the duration and timing of training in medically underserved areas were associated with subsequent settlement in such areas among physicians who obtained a medical license in 2014. We assessed cumulative exposure to medically underserved areas during the first 6 years after graduation and evaluated stage-specific exposure during junior and senior residencies. The outcome was practice in medically underserved areas 8 years after licensure. Multivariate logistic regression and marginal standardization were employed to estimate the adjusted predicted probabilities. The study included 5608 physicians, among whom 441 (7.9%) practiced in medically underserved areas 8 years after licensure. Longer cumulative exposure to medically underserved areas was associated with a higher likelihood of practicing in such areas at 8 years, with the largest increase observed between 0 and 2 years of exposure. Stage-specific analyses showed that exposure during later training stages, particularly senior residency, bore a stronger association with practice in underserved areas at 8 years than exposure during earlier stages. These findings suggest that both the duration and timing of underserved-area exposure during residency training are relevant to physician maldistribution. Although causality cannot be inferred, policies influencing specialty training placement during senior residency, in conjunction with strategies facilitating limited early exposure, may help promote practice establishment in medically underserved areas.