Income inequality and mortality: importance to health of individual income, psychosocial environment, or material conditions

Studies on the health effects of income inequality have generated great interest. The evidence on this association between countries is mixed,1–4 but income inequality and health have been linked within the United States,5–11 Britain,12 and Brazil.13 Questions remain over how to interpret these findings and the mechanisms involved. We discuss three interpretations of the association between income inequality and health: the individual income interpretation, the psychosocial environment interpretation, and the neo-material interpretation. #### Summary points Income inequality has generally been associated with differences in health A psychosocial interpretation of health inequalities, in terms of perceptions of relative disadvantage and the psychological consequences of inequality, raises several conceptual and empirical problems Income inequality is accompanied by many differences in conditions of life at the individual and population levels, which may adversely influence health Interpretation of links between income inequality and health must begin with the structural causes of inequalities, and not just focus on perceptions of that inequality Reducing health inequalities and improving public health in the 21st century requires strategic investment in neo-material conditions via more equitable distribution of public and private resources We reviewed the literature through traditional and electronic means and supplemented this with correlational analyses of gross domestic product and life expectancy and of income inequality and mortality trends based on data from the World Bank,14 the World Health Organization,15 and two British sources.16 17 According to the individual income interpretation, aggregate level associations between income inequality and health reflect only the individual level association between income and health. The curvilinear relation between income and health at the individual level 18 19 is a sufficient condition to produce health differences between populations with the same average income but different distributions of income.3 20 This interpretation assumes that determinants …