Association between the number of board-certified physiatrists and volume of rehabilitation provided in Japan: an ecological study

Objectives: This study aimed to determine the relationship between the number of board-certified physiatrists and the amount of inpatient rehabilitation delivered. Materials and Methods: We analyzed open data from 2017 in the National Database of Health Insurance Claims and Specific Health Checkups of Japan and compared the volume of inpatient rehabilitation services between prefectures to examine regional disparities. We also examined the relationship between the volume of rehabilitation services provided and the number of board-certified physiatrists. Results: The population-adjusted number of inpatient rehabilitation units per prefecture ranged from a maximum of 659,951 to a minimum of 172,097, a disparity of 3.8-fold. The population-adjusted number of board-certified physiatrists was 4.8 in the highest region and 0.8 in the lowest region, a disparity of 5.8-fold. The population-adjusted number of board-certified physiatrists was significantly correlated with the population-adjusted total number of inpatient rehabilitation units (r=0.600, P<0.001). Correlations were between the number of board-certified physiatrists and the number of rehabilitation units in cerebrovascular and orthopedic services, but not in cardiovascular, respiratory, or oncology services. Conclusion: Large regional disparities manifested in the amount of inpatient rehabilitation provided in Japan. An association was found between the number of board-certified physiatrists and rehabilitation units delivered. It may be necessary to train more BCPs in regions with fewer units to eliminate these disparities.