This study analyzed survey data conducted in preparation for the reform of physician work practices to be implemented in April 2024 to optimize physician work practices. The hospitals surveyed in this study were 81 hospitals of the Onshi Foundation Saiseikai (licensed number of beds: 22; 191 beds), which operates the largest public medical institution among social welfare corporations in Japan. Responses were collected from 1,468 full-time physicians at 76 of these hospitals through an anonymous self-administered questionnaire survey (response rate: 35%). Regression trees were created using classification and regression tree (CART), taking into consideration the bed function classification in the published bed function report and the distribution of physicians who responded to the questionnaire. The analysis showed that the hospital to which the physician belongs, the degree of fatigue, and the degree of fatigue recovery on days off have the greatest impact on job satisfaction, while self-reported indicators such as working hours, whether or not the physician has a second job at a hospital, and the number of on-call or on-call shifts do not have a significant direct impact. It was concluded that labor management needs to be considered so that physicians' health can be maintained, their job satisfaction can be improved, and high-quality medical care can be provided in a sustainable manner.
