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Spring 2011 Vol. 11 Number 1



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Why U.S. Life Spans Fall Short

Obesity, Past Smoking Among the Culprits

©Francesa Tesoriere/ImageZoo

While the U.S. spends more on health care than any other nation, this outlay has not bought us longer lives. Life expectancy has been rising at a slower rate in the U.S. than in many other high-income countries, such as Japan and France. Between 1980 and 2006, life expectancy for U.S. women increased from 77.5 to 80.7 years, but women in 21 other countries saw their life spans stretch 40 percent beyond that, on average. U.S. men had a similar, though less stark, shortfall. Concerned about the gap in longevity, the National Institute on Aging asked the National Research Council to delve into the reasons for it.

A new Research Council report says that the nation's history of heavy smoking bears much of the blame. Three to five decades ago many Americans smoked, and smoked heavily -- more so than people in Europe or Japan did -- and the results of that are still playing out in today's mortality rates. As of 2003, smoking was responsible for 78 percent of the longevity gap between women in the U.S. and those in other countries, and 41 percent of the gap for men, the report says. The habit has also damaged longevity in two other relative underachievers, the Netherlands and Denmark.

Rising rates of obesity are also likely a significant factor, the report says, though there's still a good deal of uncertainty about the nature of the link between obesity and mortality. Obesity may account for a fifth to a third of the longevity shortfall.

The committee that wrote the report also looked at whether differences in health care systems make a difference. Certainly lack of universal access to health care in the U.S. has increased mortality and lowered life expectancy, the report says. ©Science Photo Library/CorbisHowever, this is less of a factor in deaths among Americans over 65, who have access to care through Medicare. For the main causes of death at older ages -- cancer and cardiovascular disease -- available data do not suggest that the U.S. is failing to prevent deaths that could be averted elsewhere. In fact, cancer detection and survival appear to be better in the United States than in most high-income nations, and survival rates following heart attacks are favorable too.

Other factors that may make a difference in longevity are difficult to quantify, the report says. For example, some evidence suggests that adults 50 and older are somewhat more sedentary than those in Europe, but the research base is insufficient to say how much of a role this has played. Certain other factors that have been offered as explanation -- such as the use of hormone therapy in women -- do not appear to have played a role.

What does the future look like? Because there is a lag of two to three decades between smoking and its peak effects on mortality, and smoking rates have been reduced in the past 20 years, life expectancy for men in the U.S. is likely to improve relatively rapidly in coming decades. For U.S. women, whose smoking behavior hit its highest level later than men's, declines in mortality are apt to remain slow for the next decade. Similarly, life expectancy in Japan is expected to improve less rapidly than it otherwise would, because of more-recent high smoking rates.

If the obesity trend in the U.S. continues, though, it may offset the longevity improvements expected from reductions in smoking. Recent data suggest that the prevalence of obesity in the U.S. has leveled off, however, and some studies indicate that the mortality risk associated with obesity has declined. --  Sara Frueh


Explaining Divergent Levels of Longevity in High-Income Countries. Committee on Population, Division of Behavioral and Social Sciences and Education (2011, approx. 200 pages; ISBN 0-309-18640-4; available from National Academies Press, tel. 1-800-624-6242; $39.00 plus $5.00 shipping for single copies).

The committee was co-chaired by Eileen Crimmins, professor of gerontology and sociology, University of California, Davis, and Samuel Preston, Frederick J. Warren Professor of Demography, University of Pennsylvania, Philadelphia. The report was sponsored by the National Institute on Aging's Division of Behavioral and Social Research.



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Copyright 2011 by the National Academy of Sciences