Income inequality directly related to high mortality rates

ANN ARBOR—A new study by two University of Michigan epidemiologists shows that the size of the gap between the rich and the poor may tell us more about the health status of Americans than the usual economic indicators financial analysts and social scientists typically rely on.

“When we ask how well our society is doing, we often use things like the Dow Jones or measures like the gross national product. We get it in every single news report. That’s the way many people measure success in our society. The point of this study—at least in terms of public health in the United States—is that we need to consider how equitably income is distributed across the society. In essence, we need to measure the gap between the rich and the poor,” said John W. Lynch, assistant research scientist at the U-M School of Public Health.

Lynch’s study, titled “Income Inequality and Mortality in the Metropolitan Areas of the United States,” appears in the July issue of the American Journal of Public Health. Lynch, co-author George A. Kaplan, chair of the Department of Epidemiology, and a team of researchers examined the associations between income inequality and mortality in 282 U.S. metropolitan areas. The findings are startling. They found that areas with high income inequality and low average incomes had 139.8 deaths per 100,000 more than areas with low inequality and high average incomes. That difference is comparable to the combined loss of life from lung cancer, diabetes, motor vehicle crashes, human immunodeficiency virus (HIV) infection, suicide, and homicide in 1995.

“The United States has some of the highest income inequalities in the world. The United States is only exceeded by some of the former Soviet states. One obvious policy implication of these findings is that serious steps should be taken by business and government to reduce the income disparities within the United States,” Lynch said. This is the first-known study designed to estimate the total mortality costs of economic inequality across metropolitan areas of the United States.

“The implication of this study for the nation’s health is that we should not just think about how rich the United States is, or how much the GNP has grown, but how those riches are distributed and how that economic growth is shared across the population,” Lynch said.

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John W. LynchAmerican Journal of Public HealthGeorge A. KaplanhereU-M News and Information ServicesUniversity of Michigan