U.S. State-Level Social Capital and Health-Related Quality of Life: Multilevel Evidence of Main, Mediating, and Modifying Effects

PurposeThe aim of this study was to investigate the relation between state-level social capital and adult health-related quality of life (HRQOL) in the United States.MethodsUsing data from the 2001 Behavioral Risk Factor Surveillance System survey and other surveys and administrative sources, we conducted a two-level, multivariable analysis of 173,236 adults in 48 U.S. states to estimate the associations of state-level social capital (along two scales) with individual-level self-rated general health and the numbers of recent days of poor physical health, poor mental health, and activity limitation.ResultsFor each social capital scale, living in a state intermediate or high (vs. low) in social capital was each associated with 10% to 11% lower odds of fair/poor health. Higher state-level social capital also predicted fewer recent days of poor physical and mental health and activity limitation. Differential returns of social capital to HRQOL according to state-level mean income and individual-level age and race/ethnicity were observed. Furthermore, evidence was found compatible with mediation by social capital of income inequality effects on HRQOL.ConclusionsThis study yields new evidence consistent with protective effects of state-level social capital on individual HRQOL. Promoting social capital may provide a means of improving the health-related quality of life of Americans.