Life expectancy in the U.S. lags behind that of many other high-income countries and is currently ranked by the United Nations at number 28, despite spending the most on healthcare, according to a National Academy of Sciences report.
In 2006, the average life expectancy at birth was 75.1 years for American men and 80.2 years for women, rising from 47.9 years and 50.7 years, respectively, in 1900 and 65.4 and 71 in 1950.
In contrast, life expectancy for men in Japan was 79.2 years in 2007 and 86 years for women, up from 57.6 and 60.9 in 1950, respectively, reported Eileen M. Crimmins, PhD, of the University of Southern California in Los Angeles, and colleagues.
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Another success story has been France, where life expectancy for men increased from 63.4 years in 1950 to 77.4 years in 2007, and the increase for women was from 69.2 years to 84.4 years.
At the request of the National Institute on Aging, Crimmins' group looked at mortality in people over 50 years of age in more than 20 countries as recorded in the Human Mortality Database, analyzing possible reasons for the differences in life expectancy.
They determined that one strong factor was cigarette smoking, particularly for women.
Fifty years ago Americans smoked far more than residents of other countries -- and the consequences of this still strongly influence mortality today.
"The damage caused by smoking was estimated to account for 78 percent of the gap in life expectancy for women and 41 percent of the gap for men between the U.S. and other high-income countries in 2003," the report stated.
Smoking-related mortality is expected to decline among men in the near future, although likely to remain high among women for another decade or so because of historical patterns of tobacco use, according to the researchers.
Other contributory factors included obesity and lack of exercise, although the authors noted that the evidence base for these is less certain and more difficult to quantify.
In addition, although obesity is epidemic in the U.S. today, management of some of its most hazardous consequences, such as type 2 diabetes, has significantly improved.
As to the causes of death, lung cancer and respiratory disease were important, but the major contributor in the lag in life expectancy in the U.S. was heart disease, "so this condition should be a focus of efforts to bring U.S. life expectancy in line with that of the exemplar countries," the expert panel argued.
The health care system too bears some blame. "Certainly, the lack of universal access to health care in the U.S. has increased mortality and reduced life expectancy," the report stated.
The U.S. performs well in the detection and treatment of several of the main sources of early mortality, including cancer and strokes, but its major shortcomings have been its failure in preventive medicine and in curbing unhealthy lifestyles.
"Yet these behaviors are products of a broad social and economic context encompassing, for example, a level of affluence that supports large numbers of automobiles, low taxes on gasoline, and dispersed residences and workplaces that encourage driving," the report said.
That broader context also includes favorable growing conditions in parts of the country where tobacco is grown, the wide availability of inexpensive and often unhealthy foods, and inadequate social safety nets.
Moreover, the impact of unhealthy behaviors and inadequate access to health care is most concentrated at the lower end of the socioeconomic ladder.
The report concluded by calling for more detailed observational studies as well as studies that assess the effects of "natural experiments," such as health reform or increases in cigarette taxes.