Subgroup characteristics of the association between volunteering and the risk of functional disability among older Japanese people: The Tsurugaya project.

Background And Objective: Although it has been well known that volunteering is associated with a significantly decreased risk of incident disability among older people, it remains unanswered which subgroups of older people the above association is most remarkable. We aimed to identify such subgroups by conducting subgroup analyses for age, sex, chronic medical condition, and socio-demographic factors.

Methods: Participants were 826 Japanese community-dwelling people aged ≥70 years who lived in Tsurugaya, Sendai. Volunteering status was assessed with a baseline survey conducted in 2003. Incident functional disability was defined as the first certification of Long-term Care Insurance until 2017. The Cox proportional hazard model was used to estimate the multivariate-adjusted hazard ratios (HR) with 95% confidence intervals (CI) for incident functional disability. Subgroup analyses were conducted according to sex, age, medical history, marital status, and educational level.

Results: The association between current volunteering and the risk of incident functional disability was not significant (HR 0.77, 95% CI 0.56-1.06) compared to non-volunteers. In the subgroup analysis, the association between current volunteering and the risk of incident functional disability was significant among participants who were women (HR 0.52, 95% CI 0.30-0.91), those who were aged 75 years or over (HR 0.57, 95% CI 0.36-0.91), and those living without a spouse (HR 0.47, 95% CI 0.24-0.91).

Conclusion: The association between volunteering and a decreased risk of incident functional disability was remarkable among vulnerable groups such as women, those aged 75 years or over, those living without a spouse.