June 15, 2011
Between 2000 and 2007, life expectancies in more than 80% of United States counties fell in standing against the average of the 10 nations with the best life expectancies in the world, according to new research by IHME, in collaboration with researchers from Imperial College London.
The study, Falling behind: life expectancy in US counties from 2000 to 2007 in an international context, shows that compared to countries like Japan and Canada, where life expectancies significantly increase every year, most counties within the US are falling behind.
The US has extremely large racial/ethnic and geographic disparities, but data tracking these disparities at the county level are lacking. In order to assess the current state of population health, as well as to provide a baseline for future decisions that need to be made at the county level, this study compares life expectancy of US counties to those of the lowest-mortality nations to assess both absolute and relative progress for each county.
This study is part of ongoing work by IHME to better understand the current state of population health. County-level decision-makers need accurate information about local health trends, health system performance, and whether their local health systems are delivering necessary health interventions to achieve good health outcomes in their counties.
Researchers found that across US counties, life expectancy in 2007 ranged from 65.9 to 81.1 years for men and 73.5 to 86 years for women. Geographically, the counties with the lowest life expectancies for both sexes were in counties in Appalachia and the Deep South, extending across northern Texas. Counties with the highest life expectancies tended to be in the northern Plains and along the Pacific coast and the Eastern Seaboard.
One way of analyzing county-level life expectancies is to compare them to a life expectancy time series of the 10 nations with the lowest mortality, known as the “international frontier.” Compared to this international frontier, US counties range from being 16 calendar years ahead to more than 50 calendar years behind for women and from 15 calendar years ahead to more than 50 calendar years behind for men.
Nationwide, women fare more poorly than men. The researchers found that women in 1,373 counties – about 40% of US counties – fell more than five years behind the nations with the best life expectancies. Men in about half as many counties – 661 total – fell that far.
Life expectancy for black women ranges from 69.6 to 82.6 years, and for black men, from 59.4 to 77.2 years. In both cases, no counties are ahead of the international frontier, and some are more than 50 years behind. The researchers note that the poor relative performance of the US compared to the international frontier is not simply due to racial disparities, as the pattern of life expectancy performance for white Americans is similar to that of all races combined.
The researchers used newly released mortality data from the National Center for Health Statistics by age, sex, and county for the US from 2000 to 2007 to compute life tables separately for each sex, for all races combined, for whites, and for blacks. They used a mixed-effects Poisson regression with time, geospatial, and covariate components to estimate annual life expectancy for US counties.
To show county mortality in an international context, researchers compared county life expectancy to an international frontier time series, defined as the average life expectancy of the 10 countries with the lowest mortality for each year from 1950 to 2010.
Methods to address health risks are likely to narrow the disparities seen in life expectancy. The researchers note that if the leading four risk factors were addressed (smoking, high blood pressure, elevated blood glucose, and adiposity), life expectancy in 2005 would increase by 4.9 years for males and 4.1 years for females. Because risk factor exposures vary by county, and state-level analysis shows that risk factor exposures are larger in places with higher mortality rates, addressing these risk factors would tend to narrow county-level life expectancy disparities.
Given the diversity of demography, epidemiology, physical infrastructure, and health system organization at the local level, a single national solution may not be the most effective for all risk factors. To assess this, the authors call for a more comprehensive attempt to measure mortality attributable to low quality of care in the US and the impact of low quality of care on disparities. Local measurement of the baseline level of key risks and their trends may be essential for priority setting and performance evaluation in the future.
Kulkarni SC, Levin-Rector A, Ezzati M, Murray CJL. Falling behind: life expectancy in US counties from 2000 to 2007 in an international context. Population Health Metrics. 2011; 9:16.