The United States won its independence from British rule 237 years ago this month, a feat celebrated with its own holiday, and even a smash Broadway musical celebrating the overthrow of a class-based government and the rise of a poor immigrant.

But a new study shows that middle-aged people living in the U.S. today have worse health than their English counterparts – and that the difference in health between rich and poor is much larger on the American side of the Atlantic.

In fact, even the top income earners in their late 50s and early 60s in the U.S. have higher rates of diabetes, high blood pressure, arthritis and mental health conditions than their English peers, despite earning nearly twice as much in after-tax income.

But the biggest differences in health between the two nations were seen among those who make the least money. Middle-aged English people in the bottom 20% by income enjoyed better health across many measures than the poorest Americans of the same age group.

Low-income Americans were much more likely to have been diagnosed with high blood pressure, arthritis, diabetes, heart problems, stroke, chronic lung disease and mental health conditions than their low-income English peers.

They were also much more likely to have a high reading on three direct measurements taken by study staff, to test their blood pressure, blood sugar and a marker for inflammation called C-reactive protein.

The new findings about disparities in health and income are reported in a new paper in JAMA Internal Medicine, by a team from the University of Michigan and University College London.

Larger gaps among Americans

Despite the differences between the two nations, the health gaps between high-income Americans and low-income Americans were even more striking – and larger than the gaps between the same groups in England.

In all self-reported measures, except history of cancer, the graphs of each health measure by income show the worst outcomes among the lowest-income Americans, sloping down to the best outcomes among those with the highest incomes.

Direct measurements of the three key health risk factors also tracked with income, though not as closely.

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The researchers used data from two large, long-term studies conducted between 2008 and 2016, including interviews, income data and biomarkers from nearly 13,000 Americans and 5,700 English people. The disparities persisted even when the researchers adjusted for age, gender, race, household size, marital status, immigrant status and education level.

Paving the way for more research

The study provides the most comprehensive comparison to date of health status between two countries according to income levels – but it paves the way for many more studies using the same approach.

More than 30 countries are now collecting data in a way that will allow this kind of apples-to-apples comparison in future, through a network of studies funded in part by the National Institute on Aging, part of the National Institutes of Health.

The researcher team, led by HwaJung Choi, Ph.D., and Kenneth Langa, M.D., Ph.D. of the University of Michigan Medical School, focused on the age group just below the main eligibility age for Medicare health coverage in the United States. English people of all ages are covered by the National Health Service. The age of 55 was the youngest age for which nationally representative data was available for both countries.

"This approach lets us shed a lot more light on the within-country differences as well as the differences between countries," says Choi, a health economist and research assistant professor of internal medicine at U-M. "If we looked at older adults, we likely wouldn't see this level of discrepancy partly because of the effects of Medicare coverage.

"At the same time," she continues, "we may observe even greater income discrepancy in health – within and between countries -- for Americans, if we examine younger cohorts, as income inequality continues to increase in the U.S., and the health of subsequent cohorts seems even worse."

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"These are remarkable results, and confirm the value of comparisons between countries," says co-author Andrew Steptoe, D.Sc., head of the Research Department of Behavioural Science and Health at University College London. "Differences in health care are part of the story, but even in England where care is free for everyone at the point of delivery, there are still marked differences in health related to income."

Implications for COVID-19

The study even yields insights that may explain some of the extra burden of COVID-19 faced by low-income Americans, says Langa, who is the Cyrus Sturgis Research Professor of Internal Medicine, and a member of the faculty in the U-M Institute for Social Research and School of Public Health.

"Our analysis provides a comprehensive view of health disparities across many key outcomes, and shines a brighter light on the large differences in health and risk for the rich and poor in our country," he says. "A number of the disparities that we found between low-income and high-income Americans – such as a higher risk of diabetes, hypertension, and higher levels of inflammation – are likely contributing to the much higher risk for COVID-related complications and death among the poor."

The study used data from the American effort called the Health and Retirement Study, based at U-M's Institute for Social Research, and from the English Longitudinal Study of Ageing, or ELSA. Langa is associate director of HRS, and Steptoe is director of ELSA. 

Impacts of low incomes

While past studies of English and American adults have looked at health differences and economic factors, they have more-often focused on household wealth, which is different from income.

In the United States, income can make the difference between eligibility and ineligibility for health insurance programs and subsidies, especially before the expansion of Medicaid in many states in 2014.

Though the study data include two years after that expansion, the authors say they will likely not see any effects of increased health insurance coverage among lower-income Americans until more data from 2017 and beyond are made available.

The study also shows how health problems affect other aspects of life, based on income. The lowest income Americans were much more likely to have problems carrying out daily activities like shopping, cooking and managing their own money than Americans with higher incomes, and English people of similar incomes. 

SEE ALSO: Rich Seniors Are Getting Healthier, Leaving the Poor Behind

The financial stress that comes with a low income can feed into health issues, including worse health-related behaviors such as smoking and unhealthy diets, say the authors. This can lay the groundwork for serious health problems earlier in life – such as strokes at younger ages, which were seen most often in the low-income Americans in the study. 

But even high incomes didn't protect Americans from having worse health. Even the top 10% by earnings – whose after-tax median incomes were $144,000 for Americans and $71,000 for the English – had significantly worse health on four of the 16 outcomes that were studied. Americans did not have better outcomes than English adults on any of the 16 health measures, even in the highest income group.

In addition to Choi, Langa and Steptoe, the study's authors are U-M faculty Michele Heisler, M.D., M.P.H., Philippa Clarke, Ph.D., and Robert F. Schoeni, Ph.D., and research associate Tsai-Chin Cho, M.Sc., and Stephen Jivraj, Ph.D. of UCL. All the U-M faculty authors are members of the U-M Institute for Healthcare Policy and Innovation.

The Health and Retirement Study is funded by NIA (U01 AG009741) and the research project was supported by NIA grants R21 AG054818 and R01 AG053972.

Paper cited: JAMA Internal Medicine, DOI::10.1001/jamainternmed.2020.2802

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