Development of an instrument for community-level health related social capital among Japanese older people: The JAGES project

Background: We developed and validated an instrument to measure community-level social capital based on data derived from older community dwellers in Japan. Methods: We used cross-sectional data from the Japan Gerontological Evaluation Study, a nationwide survey involving 123,760 functionally independent older people nested within 702 communities (i.e., school districts). We conducted exploratory and confirmatory factor analyses on survey items to determine the items in a multi-dimensional scale to measure community social capital. Internal consistency was checked with Cronbach's alpha. Convergent construct validity was assessed via correlating the scale with health outcomes. Results: From 53 candidate variables, 11 community-level variables were extracted: Participation in volunteer groups, sports groups, hobby activities, study or cultural groups, and activities for teaching specific skills; trust, norms of reciprocity, and attachment to one's community; received emotional support; provided emotional support; and received instrumental support. Using factor analysis, these variables were determined to belong to three sub-scales: Civic participation (eigenvalue = 3.317, a = 0.797), social cohesion (eigenvalue = 2.633, a = 0.853), and reciprocity (eigenvalue = 1.424, a = 0.732). Confirmatory factor analysis indicated the goodness of fit of this model. Multilevel Poisson regression analysis revealed that civic participation score was robustly associated with individual subjective health (Self-Rated Health: Prevalence ratio [PR] 0.96; 95% confidence interval [CI], 0.94-0.98; Geriatric Depression Scale [GDS]: PR 0.95; 95% CI, 0.93-0.97). Reciprocity score was also associated with individual GDS (PR 0.98; 95% CI, 0.96-1.00). Social cohesion score was not consistently associated with individual health indicators. Conclusions: Our scale for measuring social capital at the community level might be useful for future studies of older community dwellers.