Gaping Disparity Reported in Life Span Across U.S.

Traditional Public Health Measures May Go Long Way in Closing Gap

In a stark demonstration of continuing health disparities, a new study has found a 35-year difference in longevity based on race and home county in the United States. Some groups live longer than people in some of the longest-lived countries in the world. Other Americans rival the short lives of some of the most destitute countries on Earth.

Surprisingly, much of the difference in life expectancy comes from chronic diseases and injuries in young and middle-aged adults. And access to health care does not seem to be a big factor in explaining the differences.

Photo by Graham Ramsay

The enormous disparities across the eight Americas defined in a new study by Christopher Murray (left), Majid Ezzati, and their co-authors may be addressed partly by public health strategies that reduce risk factors for chronic diseases and injuries.

“The enormous disparities, where millions of Americans have the life expectancies of people in poor and developing countries, remain the most disturbing thing in this study,” said lead author Christopher Murray, the Richard Saltonstall professor of population policy at HSPH and director of the Harvard Initiative for Global Health. “It is fundamentally difficult to understand that it’s actually that bad.”

Mapping the Gap
In what may be the largest U.S. mortality gaps measured to date, Murray and his colleagues at HSPH devised a combination of race, place of residence, and a few other demographic and geographic variables. They arranged the 3,141 U.S. counties into 2,072 to create county-units with enough deaths to measure and consistent land boundaries since 1980.

To identify distinct subgroups for targeting public health interventions, the researchers factored in other socioeconomic characteristics, such as average per-person income, homicide rates, and population density.

The result is “eight Americas.” Ordered by longevity, the groups include Asians (largely excluding Pacific Islanders), rural low-income whites in the northern plains and Dakotas, middle America (all whites, Asians, and Native Americans not counted in other groups), low-income whites in Appalachia and the Mississippi Valley, Native Americans living on or near Western reservations, black middle America, Southern low-income rural blacks, and high-risk urban blacks (see following table and graphs with descriptions and mortality differences). A gap of 20.7 years separates the longest-lived group from the shortest-lived.

Table and graphs courtesy of PLoS Medicine, Christopher Murray, and Majid Ezzati

Longevity gap. Eight distinct groups of Americans show wide disparities in mortality rates and a 20.7 year difference in longevity. The groupings are designed to help researchers explore the causes to inform specific public health intervention policies and programs.

Eight is not a magic number, the researchers emphasize. It is the smallest number of well-defined groups they could designate for their purpose of investigating the most immediate causes of the mortality disparities. Hispanics are counted mostly as whites, because the ethnicity chosen by others for their death certificates may not match their self-selected ethnicity reported to the census. Similarly, the researchers could only trust that Native Americans would be consistently identified as such in both the census and death certificate if they had lived in communities of other Native Americans who would record their certificates accurately.

“This was meant to be a simple analysis that carries a big message,” said senior author Majid Ezzati, HSPH associate professor of international health. “Part of the power of the paper comes from summarizing publicly available data in an interesting way—how many people died of what disease, at what age, of what race, and of what county of residence [and its location and characteristics].”

The Usual Suspects
Race, income, and basic health care access all contribute to the inequalities, but they do not explain everything. The results suggest that the traditional U.S. health system emphasis on young children and the elderly should be broadened to include working-age adults, the authors write in the September PLoS Medicine. The diseases contributing most to mortality disparities across the eight Americas are chronic problems and injuries with well-established risk factors, including alcohol use, tobacco smoking, overweight and obesity, and elevated blood pressure, cholesterol, and glucose.

“This is the beginning of a larger body of work that we are conducting,” Ezzati said. The study marks the first step in identifying proven risk factors and possible public health interventions that may be inadvertently contributing to inequalities even as they benefit overall public health. “To give an example,” Ezzati said, “has tobacco control been good for health? Has it been good for health inequalities? We’ll have an answer to that in the next phase of the work.”

Discussions of disparities often turn to the uninsured, but that does not appear to be a big factor in this study. “It just happens that all the groups have similar insurance coverage,” Ezzati said. “It’s not that health care doesn’t matter. It means that health care access is not making up for the underlying public health system.”

Many researchers believe that health care disparities are fundamentally related to social and economic inequalities and that long-term solutions need to address issues of discrimination and inequalities in income and education.

In addition to the need for national polices to address the underlying social determinants of health, the authors say, public health professionals need to find ways to intervene through classic medical and public health means.

“There is a lot to be done about applying things that we know work,” Murray said. “To my mind, we could make quite a bit of progress on disparities if we targeted high blood pressure, high blood sugar, inactivity, diet, tobacco, and alcohol—even if at the same time it is true that broader social inequalities explain these patterns. They are not [competing] views of the world.”

—Carol Cruzan Morton

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