The Association Between Income and Life Expectancy in the United States, 2001-2014.
Level 3 - non-randomized controlled study
Retrospective population-based observational cohort study using administrative records.
PubMed 27063997 · doi:10.1001/jama.2016.4226
What was done
Analyzed 1.4 billion deidentified US federal income tax records from 1999 to 2014 linked to Social Security Administration mortality records. The cohort included individuals aged 40 to 76 years (mean age 53.0 years, median earnings among working individuals $61,175). Investigators calculated race- and ethnicity-adjusted life expectancy at age 40 across household income percentiles, sex, and geographic regions between 2001 and 2014, and assessed correlations with area-level characteristics and health behaviors.
What was found
Across 1,408,287,218 person-year observations and 6,809,188 deaths (4,114,380 men, mortality rate 596.3 per 100,000; 2,694,808 women, mortality rate 375.1 per 100,000): - The life expectancy gap between the richest 1% and poorest 1% was 14.6 years (95% CI, 14.4 to 14.8) for men and 10.1 years (95% CI, 9.9 to 10.3) for women. - Between 2001 and 2014, life expectancy increased by 2.34 years for men and 2.91 years for women in the top 5% income bracket, compared to 0.32 years for men and 0.04 years for women in the bottom 5% (P < .001). - In the bottom income quartile, life expectancy differed by approximately 4.5 years between the highest- and lowest-longevity areas, with 2001–2014 local trends ranging from gains over 4 years to losses over 2 years. - Geographic differences in bottom-quartile longevity were negatively correlated with smoking (r = -0.69, P < .001) and positively correlated with local immigrant fraction (r = 0.72, P < .001), government expenditures (r = 0.57, P < .001), and fraction of college graduates (r = 0.42, P < .001), but were not significantly correlated with access to medical care, physical environmental factors, income inequality, or labor market conditions.
Why it matters
This study provides nationwide empirical confirmation of a massive, widening longevity gap by income in the United States, while highlighting that local health behaviors and social environments substantially influence life expectancy among low-income individuals.
Limits
The observational design precludes causal conclusions between income, local policies, and longevity. Analysis was limited to adults aged 40 to 76 and used pretax household earnings, which may not fully reflect lifetime wealth, non-taxable support, or individual clinical risk factors not captured in administrative records.