Daniel Kim

Social Capital and Health

Pick any current issue of a journal such as Social Science & Medicine or the Journal of Epidemiology and Community Health and one is bound to see a featured article about social capital and health. Search on Pubmed for “social capital and health”, and one sees over 27,500 articles listed (as of December 2006). Enter the same search term in Google, and you get over 9 million hits. Yet wind the clock back to circa 1996 and one would be hard pressed to find an article in the public health literature that even mentioned this concept. In other words, within a short span of a decade, social capital has entered the mainstream of public health discourse, where it is now the theme of professional conferences, as well as the topic of white papers put out by government health agencies worldwide. For sure social capital was talked about in fields outside public health prior to 1996 – in sociology (Bourdieu, 1986; Coleman, 1990), economics (Loury, 1992), and political science (Putnam, 1993) – but the explosion of interest in applying the concept to public health is a comparatively recent phenomenon (Figure 1.1).

Social trust and self-rated health in US communities: a multilevel analysis

This study assessed the contextual and individual effects of social trust on health. Methods consisted of a multilevel regression analysis of self-rated poor health among 21,456 individuals nested within 40 US communities included in the 2000 Social Capital Community Benchmark Survey. Controlling for demographic covariates, a strong income and education gradient was observed for self-rated health. Higher levels of cominunity social trust were associated with a lover probability of reporting poor health. Individual demographic and socioeconomic preditors did not explain the association of community social trust with self-rated health. Controlling for individual trust perception, however, rendered the main effect of community social trust statistically insignificant, but a complex interaction effect was observed, such that the health-promoting effect of community social trust was significantly greater for high-trust individuals. For low-trust individuals, the effect of community social trust on self-rated health was the opposite. Using the latest data available on community social trust, we conclude that the role of community social trust in explaining average population health achievements and health inequalities is complex and is contingent on individual perceptions of social trust. Future multilevel investigations of social capital and population health should routinely consider the cross-level nature of community or neighborbood effects.

Bonding versus bridging social capital and their associations with self rated health: a multilevel analysis of 40 US communities

Study objective: Few studies have distinguished between the effects of different forms of social capital on health. This study distinguished between the health effects of summary measures tapping into the constructs of community bonding and community bridging social capital. Design: A multilevel logistic regression analysis of community bonding and community bridging social capital in relation to individual self rated fair/poor health. Setting: 40 US communities. Participants: Within community samples of adults (n = 24 835), surveyed by telephone in 2000–2001. Main results: Adjusting for community sociodemographic and socioeconomic composition and community level income and age, the odds ratio of reporting fair or poor health was lower for each 1-standard deviation (SD) higher community bonding social capital (OR = 0.86; 95% = 0.80 to 0.92) and each 1-SD higher community bridging social capital (OR = 0.95; 95% CI = 0.88 to 1.02). The addition of indicators for individual level bonding and bridging social capital and social trust slightly attenuated the associations for community bonding social capital (OR = 0.90, 95% CI = 0.84 to 0.97) and community bridging social capital (OR = 0.96, 95% CI = 0.89 to 1.03). Individual level high formal bonding social capital, trust in members of one’s race/ethnicity, and generalised social trust were each significantly and inversely related to fair/poor health. Furthermore, significant cross level interactions of community social capital with individual race/ethnicity were seen, including weaker inverse associations between community bonding social capital and fair/poor health among black persons compared with white persons. Conclusions: These results suggest modest protective effects of community bonding and community bridging social capital on health. Interventions and policies that leverage community bonding and bridging social capital might serve as means of population health improvement.

A Multilevel Analysis of Key Forms of Community- and Individual-Level Social Capital as Predictors of Self-Rated Health in the United States

Communities may be rich or poor in a variety of stocks of social capital. Studies that have investigated relations among these forms and their simultaneous and combined health effects are sparse. Using data on a sample of 24,835 adults (more than half of whom resided in core urban areas) nested within 40 U.S. communities from the Social Capital Benchmark Survey, correlational and factor analyses were applied to determine appropriate groupings among eight key social capital indicators (social trust, informal social interactions, formal group involvement, religious group involvement, giving and volunteering, diversity of friendship networks, electoral political participation, and non-electoral political participation) at each of the community and individual levels. Multilevel logistic regression models were estimated to analyze the associations between the grouped social capital forms and individual self-rated health. Adjusting the three identified community-level social capital groupings/scales for one another and community- and individual-level sociodemographic and socioeconomic characteristics, each of the odds ratios of fair/poor health associated with living in a community one standard deviation higher in the respective social capital form was modestly below one. Being high on all three (vs. none of the) scales was significantly associated with 18% lower odds of fair/poor health (odds ratio = 0.82, 95% confidence interval = 0.69–0.98). Adding individual-level social capital variables to the model attenuated two of the three community-level social capital associations, with a few of the former characteristics appearing to be moderately significantly protective of health. We further observed several significant interactions between community-level social capital and ones proximity to core urban areas, individual-level race/ethnicity, gender, and social capital. Overall, our results suggest primarily beneficial yet modest health effects of key summary forms of community social capital, and heterogeneity in some of these effects by urban context and population subgroup.

Covariation in the socioeconomic determinants of self rated health and happiness: a multivariate multilevel analysis of individuals and communities in the USA

Objective: To investigate individual level determinants of self rated health and happiness, as well as the extent of community level covariation in health and happiness. Design: Multivariate multilevel regression analysis of self rated poor health and unhappiness at level 1, nested within 24 118 people at level 2, nested within 36 communities at level 3. Data were obtained from the 2000 social capital benchmark survey. Setting: USA communities. Participants: 24 118 adults. Main outcome measures: Self reported fair/poor health; and a single item measure of subjective wellbeing. Results: Controlling for demographic markers, a strong income and education gradient was seen for self rated poor health and unhappiness, with the gradient being stronger for poor health. Community level correlations between self rated poor health and happiness were stronger (0.65) than the individual level correlations (0.16) between the two outcomes. Conclusion: Poor health and unhappiness are highly positively correlated within individuals, and communities that are healthier tend to be happier and vice versa.

Social Capital and Physical Health

In this chapter, we describe the key findings from a systematic review of empirical studies linking social capital to physical health outcomes. As noted in the Introduction, as well as the chapters by van der Gaag and Webber (chapter 2), and Lakon and colleagues (chapter 4), much of the public health literature has focused on the health effects of social cohesion. That is, both ecological and multilevel studies have sought to examine the health impacts of group cohesion measured at different scales (e.g., neighborhoods, states, nations). In turn, a number of individual-level studies have sought to test the relationships between individual perceptions of social cohesion (e.g., trust of others) and health outcomes.

Is inequality at the heart of it? Cross-country associations of income inequality with cardiovascular diseases and risk factors

Despite a number of cross-national studies that have examined the associations between income inequality and broad health outcomes such as life expectancy and all-cause mortality, investigations of the cross-country relations between income inequality and cardiovascular disease (CVD) morbidity, mortality, and risk factors are sparse. We analyzed the cross-national relations between income inequality and age-standardized mean body mass index (BMI), serum total cholesterol, systolic blood pressure (SBP), obesity prevalence, smoking impact ratio (SIR), and age-standardized and age-specific disability-adjusted life-years (DALYs) and mortality rates from coronary heart disease (CHD) and stroke, controlling for multiple country-level factors and specifying 5- to 10-year lag periods. In multivariable analyses primarily limited to industrialized countries, countries in the middle and highest (vs. lowest) tertiles of income inequality had higher absolute age-standardized obesity prevalences in both sexes. Higher income inequality was also related to higher mean SBP in both sexes, and higher SIR in women. In analyses of larger sets of countries with available data, positive associations were observed between higher income inequality and mean BMI, obesity prevalence, and CHD DALYs and mortality rates. Associations with stroke outcomes were inverse, yet became positive with the inclusion of eastern bloc and other countries in recent economic/political transition. China was also identified to be an influential data point, with the positive associations with stroke mortality rates becoming attenuated with its inclusion. Overall, our findings are compatible with harmful effects of income inequality at the national scale on CVD morbidity, mortality, and selected risk factors, particularly BMI/obesity. Future studies should consider income inequality as an independent contributor to variations in CVD burden globally.

The contextual effects of social capital on health: a cross-national instrumental variable analysis

Past research on the associations between area-level/contextual social capital and health has produced conflicting evidence. However, interpreting this rapidly growing literature is difficult because estimates using conventional regression are prone to major sources of bias including residual confounding and reverse causation. Instrumental variable (IV) analysis can reduce such bias. Using data on up to 167,344 adults in 64 nations in the European and World Values Surveys and applying IV and ordinary least squares (OLS) regression, we estimated the contextual effects of country-level social trust on individual self-rated health. We further explored whether these associations varied by gender and individual levels of trust. Using OLS regression, we found higher average country-level trust to be associated with better self-rated health in both women and men. Instrumental variable analysis yielded qualitatively similar results, although the estimates were more than double in size in both sexes when country population density and corruption were used as instruments. The estimated health effects of raising the percentage of a countrys population that trusts others by 10 percentage points were at least as large as the estimated health effects of an individual developing trust in others. These findings were robust to alternative model specifications and instruments. Conventional regression and to a lesser extent IV analysis suggested that these associations are more salient in women and in women reporting social trust. In a large cross-national study, our findings, including those using instrumental variables, support the presence of beneficial effects of higher country-level trust on self-rated health. Previous findings for contextual social capital using traditional regression may have underestimated the true associations. Given the close linkages between self-rated health and all-cause mortality, the public health gains from raising social capital within and across countries may be large.

Do neighborhood socioeconomic deprivation and low social cohesion predict coronary calcification?: the CARDIA study.

Growing evidence suggests that neighborhood characteristics may influence the risk of coronary heart disease. No studies have yet explored associations of neighborhood attributes with subclinical atherosclerosis in younger adult populations. Using data on 2,974 adults (1,699 women, 1,275 men) aged 32-50 years in 2000 from the Coronary Artery Disease Risk Development in Young Adults (CARDIA) Study and 2000 US Census block-group-level data, the authors estimated multivariable-adjusted associations of neighborhood socioeconomic deprivation and perceived neighborhood cohesion with odds of coronary artery calcification (CAC) 5 years later. Among women, the quartiles of highest neighborhood deprivation and lowest cohesion were associated with higher odds of CAC after adjustment for individual-level demographic and socioeconomic factors (for deprivation, odds ratio = 2.49, 95% confidence interval: 1.22, 5.08 (P for trend = 0.03); for cohesion, odds ratio = 1.87, 95% confidence interval: 1.10, 3.16 (P for trend = 0.02)). Associations changed only slightly after adjustment for behavioral, psychosocial, and biologic factors. Among men, neither neighborhood deprivation nor cohesion was related to CAC. However, among men in deprived neighborhoods, low cohesion predicted higher CAC odds (for interaction between neighborhood deprivation and cohesion, P = 0.03). This study provides evidence on associations of neighborhood deprivation and cohesion with CAC in younger, asymptomatic adults. Neighborhood attributes may contribute to subclinical atherosclerosis.

Sex Differences in Stroke Incidence, Prevalence, Mortality and DALYs: Results from the Global Burden of Disease Study 2013

Background: Accurate information on stroke burden in men and women are important for evidence-based healthcare planning and resource allocation. Previously, limited research suggested that the absolute number of deaths from stroke in women was greater than in men, but the incidence and mortality rates were greater in men. However, sex differences in various metrics of stroke burden on a global scale have not been a subject of comprehensive and comparable assessment for most regions of the world, nor have sex differences in stroke burden been examined for trends over time. Methods: Stroke incidence, prevalence, mortality, disability-adjusted life years (DALYs) and healthy years lost due to disability were estimated as part of the Global Burden of Disease (GBD) 2013 Study. Data inputs included all available information on stroke incidence, prevalence and death and case fatality rates. Analysis was performed separately by sex and 5-year age categories for 188 countries. Statistical models were employed to produce globally comprehensive results over time. All rates were age-standardized to a global population and 95% uncertainty intervals (UIs) were computed. Findings: In 2013, global ischemic stroke (IS) and hemorrhagic stroke (HS) incidence (per 100,000) in men (IS 132.77 (95% UI 125.34-142.77); HS 64.89 (95% UI 59.82-68.85)) exceeded those of women (IS 98.85 (95% UI 92.11-106.62); HS 45.48 (95% UI 42.43-48.53)). IS incidence rates were lower in 2013 compared with 1990 rates for both sexes (1990 male IS incidence 147.40 (95% UI 137.87-157.66); 1990 female IS incidence 113.31 (95% UI 103.52-123.40)), but the only significant change in IS incidence was among women. Changes in global HS incidence were not statistically significant for males (1990 = 65.31 (95% UI 61.63-69.0), 2013 = 64.89 (95% UI 59.82-68.85)), but was significant for females (1990 = 64.892 (95% UI 59.82-68.85), 2013 = 45.48 (95% UI 42.427-48.53)). The number of DALYs related to IS rose from 1990 (male = 16.62 (95% UI 13.27-19.62), female = 17.53 (95% UI 14.08-20.33)) to 2013 (male = 25.22 (95% UI 20.57-29.13), female = 22.21 (95% UI 17.71-25.50)). The number of DALYs associated with HS also rose steadily and was higher than DALYs for IS at each time point (male 1990 = 29.91 (95% UI 25.66-34.54), male 2013 = 37.27 (95% UI 32.29-45.12); female 1990 = 26.05 (95% UI 21.70-30.90), female 2013 = 28.18 (95% UI 23.68-33.80)). Interpretation: Globally, men continue to have a higher incidence of IS than women while significant sex differences in the incidence of HS were not observed. The total health loss due to stroke as measured by DALYs was similar for men and women for both stroke subtypes in 2013, with HS higher than IS. Both IS and HS DALYs show an increasing trend for both men and women since 1990, which is statistically significant only for IS among men. Ongoing monitoring of sex differences in the burden of stroke will be needed to determine if disease rates among men and women continue to diverge. Sex disparities related to stroke will have important clinical and policy implications that can guide funding and resource allocation for national, regional and global health programs.