The association between income and life expectancy in the United States, 2001-2014

Abstract

IMPORTANCE: The relationship between income and life expectancy is well established but remains poorly understood. OBJECTIVES: To measure the level, time trend, and geographic variability in the association between income and life expectancy and to identify factors related to small area variation. DESIGN AND SETTING: Income data for the US population were obtained from 1.4 billion deidentified tax records between 1999 and 2014. Mortality data were obtained from Social Security Administration death records. These data were used to estimate race- and ethnicity-adjusted life expectancy at 40 years of age by household income percentile, sex, and geographic area, and to evaluate factors associated with differences in life expectancy. EXPOSURE: Pretax household earnings as a measure of income. MAIN OUTCOMES AND MEASURES Relationship between income and life expectancy; trends in life expectancy by income group; geographic variation in life expectancy levels and trends by income group; and factors associated with differences in life expectancy across areas. RESULTS: The sample consisted of 1 408 287 218 person-year observations for individuals aged40 to 76years (mean age, 53.0years; median household earnings among working individuals, $61 175 per year). Therewere 4 114 380 deaths amongmen(mortality rate, 596.3 per 100 000) and 2 694 808deathsamongwomen(mortalityrate, 375.1 per100 000). The analysis yielded 4 results. First, higher income was associated with greater longevity throughout the income distribution. The gapin life expectancy between the richest 1% and poorest 1% of individuals was 14.6 years (95%CI, 14.4 to 14.8 years) formen and 10.1 years (95%CI,9.9 to 10.3 years) forwomen. Second, inequality in life expectancy increased over time. Between 2001 and 2014, life expectancy increased by 2.34 years formenand 2.91 years forwomen in the top 5%of the income distribution, but by only0.32 yearsformenand0.04yearsforwomeninthebottom5%(P