Income inequality, the psychosocial environment, and health: comparisons of wealthy nations

Background The theory that income inequality and characteristics of the psy chosocial environment (indexed by such things as social capital and sense o f control over life's circumstances) are key determinants of health and cou ld account for health differences between countries has become influential in health inequalities research and for population health policy. Methods We examined cross-sectional associations between income inequality and low birthweight, life expectancy, self-rated health, and age-specific a nd cause-specific mortality among countries providing data in wave III (aro und 1989-92) of the Luxembourg Income Study. We also used data from the 199 0-91 wave of the World Values Survey (WVS). We obtained life expectancy, mo rtality, and low birthweight data from the WHO Statistical Information Syst em. Findings Among the countries studied, higher income inequality was strongly associated with greater infant mortality (r=0.69, p=0.004 for women; r=0.7 4, p=0.002 for men). Associations between income inequality and mortality d eclined with age at death, and then reversed among those aged 65 years and older. Income inequality was inconsistently associated with specific causes of death and was not associated with coronary heart disease (CHD), breast or prostate cancer, cirrhosis, or diabetes mortality. Countries that had gr eater trade union membership and political representation by women had bett er child mortality profiles. Differences between countries in levels of soc ial capital showed generally weak and somewhat inconsistent associations wi th cause-specific and age-specific mortality. Interpretation Income inequality and characteristics of the psychosocial en vironment like trust, control, and organisational membership do not seem to be key factors in understanding health differences between these wealthy c ountries. The associations that do exist are largely limited to child healt h outcomes and cirrhosis. Explanations for between-country differences in h ealth will require an appreciation of the complex interactions of history, culture, politics, economics, and the status of women and ethnic minorities .