Geographical disparity in paediatricians in Japan, 2002–2022: a spatial and time-series analysis

Background

The geographical maldistribution of paediatricians has long constituted a policy issue in Japan; however, the extent and temporal dynamics of this spatial disparity remain insufficiently quantified. Thus, this study aimed to analyse changes in the spatial distribution of paediatricians over two decades using spatial statistical and time-series methods.

Methods

This study included all 1,741 municipalities in Japan. The number of paediatricians by municipality was obtained from the Statistics of Physicians, Dentists and Pharmacists reports, published biennially from 2002 to 2022. The child population (CP) aged 0–14 years per municipality was obtained from the national population census database at 5-year intervals from 2000 to 2020. For years in which data were not published, values were estimated by linear interpolation. The number of paediatricians per 1,000 CP per municipality was calculated every year during the period. Municipal boundaries were standardised to the 2020 boundaries. Spatial autocorrelation analysis was applied for spatial statistics, and the Mann–Kendall test was employed for time-series analysis.

Results

From 2002 to 2022, the number of paediatricians increased by approximately 23%, with the national rate rising from 0.80 to 1.22 per 1,000 CP. Moran’s I values for paediatricians per 1,000 CP per municipality for each year from 2002 to 2022 were 0.166, 0.173, 0.168, 0.162, 0.141, 0.133, 0.109, 0.129, 0.133, 0.128, 0.116, 0.112, 0.099, 0.090, 0.076, 0.080, 0.080, 0.075, 0.062, 0.056, and 0.050, respectively, showing significant spatial clustering in all years (p < 0.001). The Mann–Kendall test revealed a significant decrease from 2002 to 2022 (Tau = -0.82, z = -5.16, p < 0.001).

Conclusions

This study quantitatively assessed the spatial distribution of paediatricians across Japanese municipalities using spatial analysis. Time-series analysis demonstrated an improvement in geographical maldistribution over time.

Key messages

• This study quantitatively assessed temporal changes in the spatial distribution of paediatricians across Japanese municipalities using spatial statistical and time-series analyses.

• This study demonstrated an improvement in the geographical maldistribution of paediatricians between 2002 and 2022, which may contribute to improved health equity in access to child health services.