Health expenditure impact of opening a new public transport station: A natural experiment of JR-Sojiji station in Japan

This study focuses on the opening of a new transit station as a possible approach to decreasing healthcare expenditure. The hypothesis was that opening a new transport station would encourage the employed people and their families to increase physical activity by improving transport accessibility. However, the causality between the building of the station and the decrease in healthcare expenditures has still not been fully understood. Therefore, this study aims to examine the impact of opening a public transport station on health expenditure per capita for medically treated employees and their families. This study adopted a natural experiment using the case of the opening of the JR-Sojiji Station in Japan. Participants were selected from the medical dataset "REZULT," which consists of aggregated health insurance claims data. The outcome was the average monthly health expenditures per capita. The exposure group was set as those who go to healthcare facilities in the Mishima and Oda districts, where JR Sojiji Station is located. The covariate group was set as those who go to healthcare facilities in other districts in Ibaraki City. The outcome was medical fee receipts from health insurers. The causal impact algorithm analyzed the causal relation using panel time series data. These results of the causal impact algorithm indicated that opening a new public transport station was significantly associated with the decrease in average cumulative health expenditures per capita by approximately JPY 99257.31 (95% confidence interval is from JPY 62119.02 to JPY 136194.37) over four years. In conclusion, this study's results are consistent with previous studies suggesting that increased access to transit may increase physical activity among transit users and may lead to a decrease in healthcare expenditures.