Abstract
BACKGROUND: Although many studies have suggested social participation (SP) has beneficial effects on elderly people's health, most of them failed to deal with paid work. Additionally, few studies have focused on the age effect between SP and older people's health. To investigate whether the association between SP, including paid work, and instrumental activities of daily living (IADL), exhibits not only in gender, but also in age among community-dwelling older adults. METHODS: In 2014, we distributed self-administered questionnaires to all community-dwelling elderly aged ≥65 in two medium-sized cities in Nara Prefecture, Japan (n = 32,825). 22,845 residents submitted the questionnaire (response rate, 69.6%). Analyzed subjects were limited to 17,680 persons who had neither dependency in basic ADL nor missing data for required items. SP was assessed based on participation frequency in seven types of social activities: volunteer groups, sports groups, hobby groups, cultural groups, senior citizens' clubs, neighborhood community associations, and paid work. Using Poisson regression models, prevalence ratio for poor IADL was calculated. To examine age and gender differences in the association between SP and IADL, we performed stratified analyses by age and gender group; male young-old (aged 65-74), male old-old (aged ≥75), female young-old, and female old-old. RESULTS: Prevalence of those with poor IADL was 17.1% in males and 4.5% in females, showing a significant gender difference. After adjustment for relevant covariates, volunteer groups were inversely associated with poor IADL only in males and the relationship was stronger in the old-old group than in the young-old group. Conversely, only females had a significant inverse association between paid work and poor IADL, and the association was not reliant on their ages but only those who participated infrequently had a favorable effect. Influence of age in the beneficial association between SP and IADL was generally larger in the old-old group than in the young-old group, but hobby groups were inversely associated with poor IADL, regardless of age, gender, and frequency. CONCLUSIONS: Our results suggest that SP in older age is positively associated with IADL, however, the association seems to differ depending on the type of activities participated in, the participants' gender, and their age.