On Death and Money: History, Facts, and Explanations

The finding that income predicts mortality has a long history. Nineteenth-century studies include Villerme1 on Paris, France, in 1817, Engels2 on Manchester, England, in 1850, and Virchow3 on Upper Silesia in 1847 through 1848. Modern analyses include the Whitehall study of British civil servants, whose status was measured by income,4 as well as similar findings for other European countries.5 Indeed, the mortality gradient by income is found wherever and whenever it is sought. Virchow’s statement3,6 that “medicine is a social science, and politics is nothing but medicine at a larger scale” has lost none of its resonance. By contrast, the medical mainstream, looking back to Koch rather than Virchow, emphasizes biology, genetic factors, specific diseases, individual behavior, health care, and health insurance. Even if it is true that the fundamental causes of health are social and economic, there is every reason to focus on treatment and health behaviors in a country, even one as rich as the United States, where poverty is intractable and there is little immediate prospect of making the distribution of income more equitable. Even so, a better understanding of how and why higher income levels are associated with increased life expectancy is needed to support any idea that tax and distribution policies could be effective tools of public health and potentially extend life expectancy. Moreover, even if income is not the main factor in the causal pathway, there is immense and justified public interest in the correlates of inequality and in the extent to which the rich not only live better but longer lives. For researchers, the topic is particularly salient today following the National Institutes of Health’s recent decision that research on financial well-being (including cost saving in health care) will no longer be eligible for funding unless the link between financial well-being and health is explicitly established.7 In this issue of JAMA, Chetty and colleagues8 report the relationship between income level and life expectancy by using the complete income tax files (1.4 billion records) from 1999 through 2014, which include age, sex, geographic location, and whether they have died. It seems unlikely that another study of income, location, and mortality will ever have more or better data. The authors collapse deaths and population by household pretax income percentile (measured 2 years prior to mortality), sex, year, age, and selected commuting zones (collections of adjacent counties around cities) or states. Mortality is adjusted for race in a reasonable but certainly not in an unchallengeable way. Mortality rates by age, sex, and income percentile are then combined by calculating period life expectancy at 40 years of age for each percentile of income each year, for men and women, and for a range of geographic areas. Only a few of the results reported by Chetty et al8 are surprising, although there is more precision and much more detail, especially on interactions between different circumstances. It is already known that individuals with higher incomes can expect to live longer than those with lower incomes and that the relationship is not simply between rich and poor, but is graded by income, hence a gradient. The relationship is clear at each and every percentile of the income distribution. Life expectancy at 40 years of age increases percentile by percentile more rapidly at the bottom, then increasing by approximately 1 year per 9 percentiles of household income for men and approximately 1 year per 20 percentiles of household income for women. As a consequence, the male-female gap in life expectancy at 40 years of age shrinks across the income distribution from 6.2 years in the bottom income percentile to only 1.5 years in the top income percentile. The gaps from top to bottom income percentiles are large: more than 10 years for women and 15 years for men. The rate of change of life expectancy at 40 years of age from 2001 through 2014 is faster in the top income quartile but is positive even for men and women in the bottom income quartile. The main findings confirm previous work on different samples, sometimesof the samedata.9-11Notonlydoes the top 1% of the income distribution live longer than everyone else, but the gap in life expectancy at 40 years of age is widening, and therehasbeen little gain in life expectancyamong the lowest income individuals living in the United States. The infamous 1% is not only richer, but much healthier. Conditional on reaching 40 years of age, individuals in the top 1% of incomehave 10 to 15moreyears toenjoy their richly funded lives and to spend timewith their children and grandchildren, and they arepulling away fromeveryone else. Inequality inhealth reinforces inequality in income, andperhaps evena longer life is for sale. The report by Chetty et al8 also suggests that geography and income percentiles interact in previously unknown ways. For instance, the percentile gradient for life expectancy at 40 years of age is steeper in Detroit, Michigan, than Editorials pages 1706 and 1709