Life expectancy in the U.S. varies widely when analyzed at the census-tract level, a new study from Harvard T.H. Chan School of Public Health finds.
For instance, at the county level, Allegheny County, Pennsylvania, has a life expectancy of 77.4 years.
But the researchers found that the county contained a census tract with a life expectancy of 62 years and another census tract with a life expectancy of 86 years, a 24-year difference.
Similarly, at the county level, Chatham County, North Carolina, has a life expectancy of 80.4 years.
But it contained a census tract with a life expectancy of 76.2 years and a census tract with a life expectancy of 97.5 years, a 21-year difference.
Data on many public health indicators, including life expectancy, is often gathered and analyzed at the county or state level.
Focusing on counties or states, however, may fail to highlight significant health disparities at the local level.
The study is the first to analyze life expectancy data at the census-tract level across the contiguous U.S., as well as at the state and county level.
Census tracts are small geographic units that typically range in population from 1,200 to 8,000 residents.
The study’s approach may provide a more detailed picture of health disparities in the U.S. than other widely used analyses of life expectancy, the researchers said.
“Our study shows that as far as geographic variation in life expectancy is concerned, it’s a pretty local phenomenon,” said S (Subu) V Subramanian, professor of population health and geography and co-author of the study.
The findings were published online July 13, 2020 in Proceedings of the National Academy of Sciences (PNAS).
Focusing on counties or states, however, may fail to highlight significant health disparities at the local level.
For this study, the research team analyzed life expectancy data in 65,662 census tracts that were nested in 3,020 counties across 48 states.
The researchers also found that socioeconomic and demographic variables, especially education, income, and race, were strongly associated with life expectancy at the census-tract level.
Analyzing life expectancy and other public health data at the census-tract level can help illuminate significant local health disparities and aid in the development of better and more targeted public health interventions and policies, according to the researchers.
“Quantifying and explaining variation in life expectancy at census tract-, county-, and state-levels in the US,” Antonio Fernando Boing, Alexandra Crispim Boing, Jack Cordes, Rockli Kim, SV Subramanian, Proceedings of the National Academy of Sciences, online July 13, 2020, doi: 10.1073/pnas.2003719117.
Adapted from a press release from Harvard T.H. Chan School of Public Health.
