But disparities in longevity still tied to geography, race and income, study shows
TUESDAY, March 23 (HealthDay News) -- Americans who smoke, have high blood pressure, high blood sugar and are overweight may be shortening their life expectancy by an average of four years, a new study finds.
In fact, men may be shortening their lives by 4.9 years while women could be shaving 4.1 years off their lives, the researchers say. However, there is even greater variance in the effects of these factors on life expectancy across the United States based on geography, race and income.
"These risk factors are cutting life expectancy for any average American," said lead researcher Majid Ezzati, an associate professor of international health at the Harvard School of Public Health in Boston.
"That number is actually quite larger in some groups than others," he said. "It is getting to six or seven years for some of the disadvantaged groups."
The message: Not smoking, maintaining a healthy body weight, keeping blood pressure down and keeping blood sugar levels low will help people live longer. This will not only save a lot of lives, but benefit the most disadvantaged the most, Ezzati added.
The report is published in the March edition of the online journal PLoS Medicine.
For the study, Ezzati's team collected data on people who participated in the 2005 studies from the U.S. National Center for Health Statistics, the National Health and Nutrition Examination Survey and the Behavioral Risk Factor Surveillance System. They also looked at epidemiologic studies on the effects of these risk factors.
Based on the data, the researchers were able to estimate the number of deaths that would have been prevented if these risk factors were at optimal levels and how optimal levels would increase life expectancy.
In addition, they estimated these factors for subgroups in the United States known as the "Eight Americas." These are groups defined by race, county location and the socioeconomics of each county. The Eight Americas were defined by the authors in an earlier study as Asians; Northland low-income rural whites; middle America; low-income whites in Appalachia and Mississippi Valley; Western Native Americans; Black middle America; high-risk urban blacks; and Southern low-income rural blacks.
The researchers found that the four risk factors account for a large part of the difference in life expectancy among these groups. For example, among Southern rural blacks these risk factors took the highest toll, reducing life expectancy by 6.7 years among men and 5.7 years among women. Asians saw the lowest reduction in life expectancy, 4.1 years for men and 3.6 years for women.
Ezzati's group found that Asian Americans had the lowest body mass index (or BMI, a measurement that takes into account weight and height), the lowest blood sugar levels and the fewest smokers. Blacks had the highest blood pressure. Whites had the lowest blood pressure, while Western Native American men and Southern low-income rural black women had the highest BMI. In addition, the heaviest smokers were Western Native Americans and low-income whites in the Appalachia and Mississippi Valley.
The patterns of smoking, high blood pressure, high blood glucose and overweight/obesity account for almost 20 percent of differences in life expectancy across the country, Ezzati said. These four risk factors account for 75 percent of differences in cardiovascular deaths and up to 50 percent of differences in cancer deaths in various areas of the United States.
"When we talk about disease prevention and saving lives we shouldn't just talk about the numbers, we should talk about whose lives you are saving," Ezzati said.
Ezzati thinks that public health efforts to reduce these risk factors need to be targeted to the groups that need them most.
According to the report, if these risk factors were at optimal levels, the increased life expectancy would be:
Dr. David L. Katz, director of the Prevention Research Center at Yale University School of Medicine, noted that the fact that there are significant health disparities across the United States, including life expectancy, that relate to ethnicity, socioeconomics and geography is well known.
This study takes it a bit deeper, by showing specific patterns of variation in smoking, blood pressure, blood glucose and body fat, Katz noted. "What is most notable about these four factors, which individually and collectively translate into an enormous and disparate toll of preventable disease and premature death, is that they are all fully controllable," he said.
Smoking and body fat are directly controllable by people themselves, Katz pointed out. Blood pressure and blood sugar can be controlled by lifestyle, but when they are at abnormal levels they need to be treated medically, he added.
"Clearly, neither patients nor doctors are getting this essential job done in the groups and counties most encumbered," Katz said. "We knew about disparate outcomes, and now we know about disparate risk factors. The next thing we need to identify is the various reasons for poor risk factor management, and the requisite steps to address them systematically. Until this job is done, lives will be lost prematurely, and avoidably."
For more information on healthy living, visit the U.S. National Library of Medicine.
SOURCES: Majid Ezzati, Ph.D., associate professor, international health, Harvard School of Public Health, Boston; David L. Katz, M.D., M.P.H., director, Prevention Research Center, Yale University School of Medicine, New Haven, Conn.; March 23, 2010, PLoS Medicine, online
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