Study reveals stark life expectancy disparities across the United States

Life expectancy in the USA varies by more than 20 years depending on an individual's race and ethnicity and where they live. These widespread and persistent life expectancy disparities have divided the country into "ten Americas," according to new research examining inequities in US life expectancy between 2000 and 2021, published in The Lancet. 

The extent and magnitude of health disparities in American society are truly alarming in a country with the wealth and resources of the USA. These disparities reflect the unequal and unjust distribution of resources and opportunities that have profound consequences on well-being and longevity, especially in marginalised populations. Policymakers must take collective action to invest in equitable health care, education, and employment opportunities and challenge the systemic barriers that create and perpetuate these inequities so that all Americans can live long, healthy lives regardless of where they live and their race, ethnicity, or income."

Christopher JL Murray, Senior Author, Professor Director of the Institute for Health Metrics and Evaluation (IHME), University of Washington, Seattle, USA

The findings come nearly two decades after the landmark "Eight Americas" study, which examined the interacting drivers of health inequities in the USA by dividing the US population into eight groups based on geography, race, urbanicity, income per capita, and homicide rate. 

In this new study, researchers update and expand the original Eight Americas study, dividing the US population into ten mutually exclusive populations, or 'Americas', based on race and ethnicity and other variables such as geographic location, metropolitan status, income, and residential segregation (see table in notes to editors).

Analysing death records from the National Vital Statistics System and population estimates from the National Center for Health Statistics, researchers estimated trends in life expectancy at birth-;an important indicator of a population's health-;from 2000 to 2021 for each of the ten Americas by year, sex, and age group.

Stark differences in life expectancy have widened over two decades

Despite efforts to reduce health inequalities, the life expectancy gap between the Americas was 12.6 years in 2000 and grew even larger during the 2000s and 2010s (reaching 13.9 years in 2010 and 15.6 years by 2019), and accelerated to 20.4 years after the first two years of the COVID-19 pandemic (see table in notes to editors).

In 2000, Black Americans living in rural, low-income counties in the South (America 9) and Black Americans living in highly-segregated cities (America 7) had the lowest life expectancy (around 70.5 years for both populations), while Asian Americans (America 1) had the highest life expectancy, living on average 83.1 years.

Between 2000 and 2010, life expectancy increased for every America except for American Indian and Alaska Native (AIAN) people living in the West (America 10), who had the shortest lifespan in 2010 after a one-year drop in life expectancy from 72.3 years in 2000 to 71.2 years in 2010.

During this time, the three Black Americas (6, 7, and 9) showed some of the largest gains in life expectancy, increasing by as much as 3.7 years, with Black Americans living in other counties (America 6) exceeding the life expectancy of White Americans living in low-income counties in Appalachia and the lower Mississippi Valley (America 8) from 2010 onwards, except in 2020.

"The gap between life expectancy at birth for Black and White Americans may never have been narrower than it was in the mid-2010s," said co-author Thomas Bollyky from the Council of Foreign Relations, Washington DC, USA. "It's likely that long-term improvements in education available to Black children and young adults in recent decades, as well as reductions in homicide rates and deaths from HIV/AIDS-;causes of death that have disproportionately impacted Black Americans-;may have contributed to these noteworthy gains for Black Americans."

However, in the following decade (2010-2019), improvements in life expectancy at birth for the three Black Americas (Americas 6, 7, and 9)-;as well as all the other Americas-;largely stalled (see table in notes to editors). This pattern may be explained by an increase in drug overdose deaths and homicides as well as a slowdown in reductions in cardiovascular disease deaths, likely related to increases in obesity.

Widening racial life expectancy gap during the first two years of the COVID-19 pandemic 

The COVID-19 pandemic precipitated a staggering drop in life expectancy for all the Americas and substantially widened racial disparities in lifespan. For example, while Black Americans living in highly segregated cities (America 7) and Black Americans living in rural, low-income counties in the South (America 9) were expected to live an average 74.9 years and 72.5 years, respectively, in 2019, this fell by approximately 4.0 years in 2020. For White (the majority), Asian, and AIAN people living in other counties (America 3), the corresponding decline was only 1.4 years-;from 79.3 years in 2019 to 77.9 years in 2020.

Marginalised groups already had lower life expectancy, and the pandemic further increased the gap. By 2021, Asian Americans (America 1) still had the longest life expectancy at birth, living on average 84 years-;a striking 20.4 years longer than AIAN people living in the West (America 10), who had the lowest life expectancy at 63.6 years.

Alarming health crisis for American Indian and Alaska Native people in the West

AIAN people living in the West (America 10) were the only group to experience a drop in their life expectancy between 2000 and 2010 and again between 2010 and 2019-;falling from the already relatively low 72.3 years in 2000 to 70.2 years in 2019. COVID-19 set them even further behind the other Americas, with a 6.6-year drop in life expectancy between 2019 and 2021.

These findings suggest that AIAN people are living much shorter lives than any other population due to systemic barriers that have perpetuated social, economic, and health inequities. For example, inadequate healthcare access and chronic underfunding of Indigenous health services, together with high rates of unemployment and low rates of educational attainment, and the legacy of systemic discrimination, are factors that likely contribute to AIAN people dying at higher rates from highly preventable causes like chronic diseases, smoking, and drug overdose, as well as COVID-19. 

What is driving these disparities in life expectancy?

The findings suggest that differences in educational attainment and income likely explain some of the disparities in life expectancy. For example, Black Americans living in rural, low-income counties in the South (America 9) and AIAN individuals living in the West (America 10) had the lowest income per capita and percentage graduating college as well as the lowest life expectancy in most years between 2000 and 2021.

However, the authors note some unexpected disparities, which indicate that other factors beyond income and education can contribute to differences in longevity. For example, White (the majority), Asian, and AIAN people living in other counties (America 3) had the highest income in most years, as well as the highest proportion graduating high school and the second highest percentage of college graduates but was ranked only fourth or fifth in life expectancy prior to 2020. 

According to co-author Professor Ali Mokdad from IHME: "More research is needed to fully understand why life expectancy is worse for some Americans so we can better tackle the root causes of poor health for the most disadvantaged. America's life expectancy gap is unlikely to diminish until a comprehensive, coordinated approach that includes preventive measures and public health initiatives that transcend political divides and fosters collaboration and accountability between state, local, and national entities is developed. Only then can we hope to create a more equitable and healthier society for all the Americas-;and all Americans."

The authors point out that the grouping of the US population based on county, race and ethnicity is not the only division that could be used to understand the large inequalities in US life expectancy, and different choices of factors would lead to different results. 

The authors also note some important study limitations, including that there is a well-known misreporting of race and ethnicity on death certificates, and although they corrected for this misclassification, it increased the uncertainty around the estimates. They also note that data on income per capita and educational attainment from the America Community Survey and 2000 decennial census used different racial and ethnic groups compared to those used in the analysis, which could lead to a mismatch in the estimates of income and educational attainment for three groups (combined AIAN, Asian and NHPI, and Black) and the corresponding Americas. Additionally, while this analysis shows large disparities in life expectancy between the ten Americas, the authors note that there will also be large disparities within these Americas. For example, research shows considerable differences in life expectancy among counties, even for the same racial and ethnic group. Finally, while the ten Americas is defined based on data from a single point in time (primarily 2020), some of the characteristics these definitions are based on are time-varying (eg, income per capita), so it is likely that some county and race and ethnicity combinations would be included in different Americas if data from a different year were used to define the Americas.

Writing in a linked Comment, Professor Steven H Woolf from the Virginia Commonwealth University School of Medicine, USA (who was not involved in the study), says that the study confirms the continued existence of different Americas in the USA, adding that: "The study also underscores the value of investigating intersectionality. Disaggregated data can inform policy decisions about which geographic regions and populations to prioritise in efforts to reduce disparities in life expectancy. Understanding the root causes of disparate mortality rates and meaningful efforts to address the social and environmental determinants of health are essential to close the gap."