[Association between subjective change and risk of disability in older adults following the introduction of electric-powered carts: A one-year longitudinal study].

Objective　The Ministry of Land, Infrastructure, Transport, and Tourism of Japan has recently been promoting the adoption of green (i.e., electric-powered) slow mobility carts, which can operate on public roads at speeds <20 km/h. A two-month trial of electric-powered cart services showed improvements in subjective indicators such as social interaction among older adults, with potential long-term benefits related to preventing the eventual need for long-term care (LTC). This study investigated whether the risk of requiring LTC decreased one year after the introduction and use of electric-powered carts in older adults whose subjective indicators improved following the introduction of the service.Methods　Electric-powered cart services were introduced in Kawachinagano City (Osaka Prefecture) and Oji Town (Nara Prefecture), beginning in July-August of 2022. Our analysis included 726 adults aged ≥65 years (385 from Kawachinagano City and 341 from Oji Town) who provided valid responses to a self-administered postal survey conducted at the baseline (i.e., when the program was introduced), as well as at a follow-up one year later. At the follow-up, operations had concluded in Kawachinagano City, but continued in Oji Town. LTC risk at the one-year follow-up was assessed using the LTC risk assessment scale, with higher scores indicating a greater risk. The explanatory variables included electric-powered cart usage (defined as cart usage several times per year or more) and changes in subjective indicators prompted by cart usage. The subjective indicators assessed were outings (three items), social activities (five items), and positive emotions (four items). Covariates included sex, LTC risk score, educational background, subjective economic status, employment, activities of daily living, marital status, and cohabitation at the baseline survey. Missing data were handled using multiple imputations (m = 200). Linear regression analysis was used to calculate the coefficients (B).Results　Of the total respondents, 290 (39.9%) reported using the electric carts. Electric-powered cart use was not significantly associated with LTC risk (B = 0.11, 95% confidence interval [CI]: -0.40 to 0.63). No significant associations were found between changes in subjective indicators and LTC risk across the overall cohort. However, in Oji Town, older adults who reported increase in positive emotions such as enjoyment of daily life (-1.78, -3.21 to -0.35), feeling uplifted (-1.51, -2.87 to -0.15), and finding life more meaningful (-1.91, -3.53 to -0.30) showed significant reductions in LTC risk.Conclusion　While no overall association was found between electric-powered cart usage and LTC risk, certain positive emotional changes reported in the respondents from Oji Town were associated with reduced LTC risk. These findings suggest that electric-powered carts may contribute not only to mobility support but also to LTC prevention, by fostering positive emotions among older adults.