An important debate in the social health literature is whether more inequality causes worse health. At some later date I’ll post a bibliography, or maybe commenters can help. In any case the list of publications is long, the contributors illustrious, and the findings varied and at odds with each other. Some of the most important papers representing a range of findings include those by Deaton, Deaton and Lubotsky, Mellor and Milyo, Lynch, et al., Kawachi, Subramanian, et al., Navarro, et al., Wilkinson, et al., and Marmot, et al.
Note that the debate is about the effect of inequality, per se, on health. Everybody knows that being rich reduces mortality and being poor increases it. The relationship between income and health (mortality, infant mortality, life expectancy, morbidity) is so well known in the literature that it is simply known as “the gradient.” It obtains at the macro and micro levels in dozens of studies. For example, let me quote Angus Deaton, who is BTW an inequality-mortality skeptic, “Men in the United States with family incomes in the top 5 percent of the distribution in 1980 had about 25 percent longer to live than did those in the bottom 5 percent. Proportional increases in income are associated with equal proportional decreases in mortality throughout the income distribution” (Angus Deaton “Policy Implications Of The Gradient Of Health And Wealth”). But I digress.
There are three basic channels through which an association between inequality and health could occur. The first two are causal in that social inequality affects individual health.
- Direct. Inequality creates stress, which is bad for health.
- Indirect. Inequality disrupts the production of health-supporting public goods or causes the production of health-reducing public bads, which is bad for health.
- Artifactual. More income improves the health of the poor more than it improves the health of the rich. (The health-income relationship is concave.) A more unequal society will have worse average health than a more equal society with the same mean income because the health gain to the rich from being much richer is not as great as the health loss to the poor from being much poorer. Note that individual income only affects individual health, but the distribution of income affects average health.
A fairly recent entry in the field is Leigh and Jencks, “Inequality and mortality: Long-run evidence from a panel of countries” (Journal of Health Economics 26 (2007) 1-24). Here is a link to a working paper version which is very similar to the published version. In a nutshell, the income share of the richest 10 percent of the population is the measure of inequality, and life expectancy at birth and infant mortality are the two main measures of health outcome. Read more