Income inequality and population health

Evidence favouring a negative correlation between income inequality and life expectancy has disappeared

Papers pp 13, 16, 20, 23

In 1992, the BMJ published a now famous paper showing a strong negative correlation between income inequality and life expectancy. Among nine Western industrialised countries those which had less income inequality seemed to have higher life expectancy.1 A few years later this was replicated in analyses looking at income inequality and mortality in states within the United States—analyses which seemed more secure because of having more and better quality data. 2 3 These findings, which suggested that income inequality is bad for the health of the whole population and not only for those with the lowest incomes, were seen to have important implications. Reducing the inequality would be in everyone's interest, including those with higher incomes.

A novel area of research was born, adding new perspectives to conventional studies of health inequalities. These had tended to focus on relations between socioeconomic factors and health of the individual, while the findings on income inequality suggested that contextual effects of inequality might be just as important. Considerable dissent, however, emerged on the explanation of these effects. Some favoured softer psychosocial pathways (for example through feelings of relative deprivation, or disruption of social cohesion) while others favoured harder material pathways (for example through underinvestment in public resources).4^–6 Support was found for some of these mechanisms, which are also important in their own right, and the debate on income inequality versus mortality acted as a strong stimulus for further work on factors such as social cohesion and social capital.7 Although most of …