Poverty has long been recognized as a contributor to death and disease, but several recent trends have generated an increased focus on the link between income and health. First, income inequality in the United States has increased dramatically in recent decades, while health indicators have plateaued, and life expectancy differences by income have grown. Second, there is growing scholarly and public recognition that many nonclinical factors—education, employment, race, ethnicity, and geography—influence health outcomes. Third, health care payment and delivery system reforms have encouraged an emphasis on addressing social determinants of health, including income.

In this brief, we review the evidence supporting the income-health relationship and the likely mechanisms through which income affects health. We then discuss the growing importance of this association, given widening income inequality, and discuss policy levers that might help reduce income-related health disparities.

Income And Health—The Evidence

Economic inequality is increasingly linked to disparities in life expectancy across the income distribution, and these disparities seem to be growing over time. In the 1970s, a sixty-year-old man in the top half of the income distribution could expect to live 1.2 years longer than a man in the bottom half. By the turn of the century, he could expect to live 5.8 years longer.

A landmark study by Raj Chetty and colleagues found that since 2001, life expectancy has increased by about 2.5 years for the top 5 percent of the income distribution, but there have been no gains for those in the bottom 5 percent. Men in the top 1 percent of the income distribution can now expect to live fifteen years longer than those in the bottom 1 percent. For women, the difference is about ten years—an effect equivalent to that of a lifetime of smoking.

While stark disparities in mortality along the economic gradient understandably capture our attention, we should not overlook substantial income-related differences in morbidity. The United States has among the largest income-based health disparities in the world: Poor adults are five times as likely as those with incomes above 400 percent of the federal poverty level to report being in poor or fair health.

In a nearly stepwise fashion, low-income Americans have higher rates of physical limitation and of heart disease, diabetes, stroke, and other chronic conditions, compared to higher-income Americans. Americans living in families that earn less than $35,000 a year are four times as likely to report being nervous and five times as likely to report being sad all or most of the time, compared to those living in families earning more than $100,000 a year. These disparities emerge early in life and can be transmitted across generations. For the 6.8 million children living in deep poverty (those with family incomes of less than half of poverty), there are adverse consequences across the life course related to nutrition, environmental exposures, chronic illness, and language development.

It is important to clearly distinguish between income and wealth. This brief focuses on income, which refers to the sum of wages, salaries, and other earnings in a given time period. By contrast, wealth encompasses the total value of assets and debts held by a person or family. Compared to income, wealth is harder to study and more unequally distributed, and it may be more important for health disparities that persist over generations.

Read more at Health Affairs