LAUSR

Purpose Increasing the number of physicians per population may improve the quality of medical services, but there are few reports on this aspect in the field of surgery. This study aimed to examine whether the number of physicians is associated with the number of nighttime emergency surgeries, which may be one of the indicators of the quality of medical services in the field of surgery. Methods This was a prefecture-based ecological study utilizing open data from Japanese government surveys conducted between 2015 and 2019. The relationship between the number of physicians and the number of nighttime emergency surgeries in 47 prefectures of Japan was evaluated by correlation analysis and panel data regression analysis. The correlation analysis was conducted between the number of physicians per 100,000 population and the number of nighttime emergency surgeries per 100,000 population per year in each prefecture in Japan. In the panel data regression analysis, panel data of the prefectures in Japan from 2015 to 2019 were created. We evaluated whether the number of physicians was related to the number of nighttime emergency surgeries, independent of the number of acute care beds per 100,000 population, population density, and the elderly population ratio. Results From the correlation analysis, the correlation coefficient between the number of physicians per 100,000 population and the number of nighttime emergency surgeries per 100,000 population was 0.533 (P < 0.001). In the panel data regression analysis, there was a significant association between the number of physicians per 100,000 population and the number of nighttime emergency surgeries per 100,000 population (P < 0.001). The regression coefficient (95% confidence interval) for the number of physicians per 100,000 population was 0.246 (0.113–0.378). Conclusion The number of physicians is associated with the number of nighttime emergency surgeries.