The researchers also estimated the effects of these risk factors on eight subgroups of the U.S. population, called the “Eight Americas.” 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 studied information on deaths from different diseases in 2005 from the U.S. National Center for Health Statistics, and estimates of how much each risk factor increases the risk of death from each disease from published studies.
The study found that national life expectancy in the U.S. in 2005 was 75.1 for men and 80.3 for women. Asians had the highest life expectancy at birth in the Eight Americas, reaching 86.8 for women and 82.3 for men (about 1 and 2 years higher than the highest life expectancies in the world). Blacks had the lowest life expectancy in both men (68.1 y in the rural South and high-risk urban areas) and women (74.9 y in the rural South). The researchers found a declining life expectancy gradient from America 1 to Americas 7 and 8, with the 14 and 12 year gaps in men and women equal to those observed between middle- and high-income countries worldwide.