Do people die from income inequality of a decade ago?

Soc Sci Med. 2012 Jul;75(1):36-45. doi: 10.1016/j.socscimed.2012.02.042. Epub 2012 Mar 28.


The long-term impact of income inequality on health has not been fully explored in the current literature. Until now, 4 studies have examined the lagged effect on population/group mortality rate at the aggregate level, and 7 studies have investigated the effect of income inequality on subsequent individual mortality risk within a restricted time period. These 11 studies suffer from the same limitation: they do not simultaneously control for a series of preceding income inequalities. The results of these studies are also mixed. Using the U.S. National Health Interview Survey data 1986-2004 with mortality follow-up data 1986-2006 (n = 701,179), this study investigates the lagged effects of national-level income inequality on individual mortality risk. These effects are tested by using a discrete-time hazard model where contemporaneous and preceding income inequalities are treated as time-varying person-specific covariates, which then track a series of income inequalities that a respondent faces from the survey year until s/he dies or is censored. Findings suggest that income inequality did not have an instantaneous detrimental effect on individual mortality risk, but began exerting its influence 5 years later. This effect peaked at 7 years, and then diminished after 12 years. This pattern generally held for three measures of income inequality: the Gini coefficient, the Atkinson index, and the Theil entropy index. The findings suggest that income inequality has a long-term detrimental impact on individual mortality risk. This study also explains discrepancies in the existant literature.

MeSH terms

  • Confidence Intervals
  • Health Status Disparities*
  • Health Surveys
  • Humans
  • Income / statistics & numerical data*
  • Models, Statistical
  • Mortality / trends*
  • Odds Ratio
  • Proportional Hazards Models
  • Risk*
  • Social Class
  • Social Justice
  • Socioeconomic Factors
  • Time*