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

Purpose The 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. Methods Using 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. Results For 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. Conclusions This 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.