Future projection of the physician workforce and its geographical equity in Japan: a cohort-component model

INTRODUCTION: The geographical inequity of physicians is a serious problem in Japan. However, there is little evidence of inequity in the future geographical distribution of physicians, even though the future physician supply at the national level has been estimated. In addition, possible changes in the age and sex distribution of future physicians are unclear. Thus, the purpose of this study is to project the future geographical distribution of physicians and their demographics. METHODS: We used a cohort-component model with the following assumptions: basic population, future mortality rate, future new registration rate, and future in-migration and out-migration rates. We examined changes in the number of physicians from 2005 to 2035 in secondary medical areas (SMAs) in Japan. To clarify the trends by regional characteristics, SMAs were divided into four groups based on urban or rural status and initial physician supply (lower/higher). The number of physicians was calculated separately by sex and age strata. RESULTS: From 2005 to 2035, the absolute number of physicians aged 25–64 will decline by 6.1% in rural areas with an initially lower physician supply, but it will increase by 37.0% in urban areas with an initially lower supply. The proportion of aged physicians will increase in all areas, especially in rural ones with an initially lower supply, where it will change from 14.4% to 31.3%. The inequity in the geographical distribution of physicians will expand despite an increase in the number of physicians in rural areas. CONCLUSIONS: We found that the geographical disparity of physicians will worsen from 2005 to 2035. Furthermore, physicians aged 25–64 will be more concentrated in urban areas, and physicians will age more rapidly in rural places than urban ones. The regional disparity in the physician supply will worsen in the future if new and drastic measures are not taken.