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Life expectancy in the U.S. varies widely, based not on how much you earn or how good your health insurance is, but on where you live. A new study by Harvard University researchers found a gap of 33 years between the longest-lived group of Americans—Asian American women in Bergen County, N.J., with an average life expectancy of 91 years—and the shortest, Native Americans in a cluster of rural counties in South Dakota, at 58 years. The only other major industrialized nation with such a large "longevity gap" is Brazil.
The researchers, led by Dr. Christopher J.L. Murray, concluded that life expectancy is primarily determined by the prevalence of chronic illnesses such as heart disease and cancer and injuries from alcohol-related traffic accidents. In what came as a surprise to the researchers, income, infant mortality rates, violence, and lack of health insurance had little effect on the overall life expectancy of any given area. "This study seems to indicate that the factors that determine longevity primarily affect young and middle-aged adults, not young children and the elderly," says Dr. Murray. Rather than focusing on interventions for the very young and very old, he suggests "inexpensive interventions to control blood pressure, cholesterol, smoking, and drinking could have a very large impact on longevity."
The researchers correlated average life expectancy in every U.S. county with data on race, income, population density, and murder rate. Hawaii had the highest life expectancy of any state, 80 years, while seven counties in Colorado topped the county-by-county rate. Washington, D.C., tied Edgecombe County in North Carolina for last, with an average life expectancy of only 72 years. Dr. Murray noted that the life expectancy gap between the highest and lowest counties has been steadily widening since 1984. "The counties that started the best just keep getting better. Those at the bottom either stayed the same or worsened," he says.
DISPARITIES WITHIN RACES.
Although there have been numerous studies indicating that minorities and the poor lack access to good quality health care, the researchers discovered that race and income did not play a large role in predicting longevity. For example, low-income, rural white populations in northern Minnesota, as well as Montana and Nebraska, had a relatively high average life expectancy of 76.2 years for men and 81.8 years for women. But life expectancy for whites with similar low incomes in rural Appalachia and the Mississippi Valley was much lower. Dr. Murray says insurance coverage and use of routine health care did not explain the difference. "It is overwhelmingly clear that the greatest disparity is among young and middle-age adults, not infants and the elderly" he says.
There were even significant disparities within racial groups. For example, while longevity rates for Native Americans overall are about the same as those for whites, life expectancy is much lower for Native Americans who live on or near reservations in the West. Analysis of the cause of death for those in proximity to reservations showed a high toll from alcohol, such as traffic accidents, cirrhosis of the liver, and diabetes.
The researchers also discovered that the longevity gap between men and women has narrowed over time, primarily because fewer men are smoking. Also, Asian Americans keep improving their longevity, while poor whites in Appalachia are getting worse. The study appears in the September issue of the journal PloS Medicine.
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