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Harvard Medical School Office of Communications & External Relations

Universal coverage may narrow racial, ethnic and socioeconomic gaps in health outcomes

A study examining health data for more than 6,000 adults over an eight-year period found that disparities in important health outcomes by race, ethnicity and education were substantially reduced after these adults gained universal health coverage through the Medicare program. Researchers looked at indicators of cardiovascular disease and diabetes control and found that while disease control improved for everyone between 1999 and 2006, important socio-demographic gaps remained or, in some cases, widened. After Medicare coverage at age 65, however, these gaps completely closed in some cases.

Health care disparities among various racial, ethnic and socioeconomic groups have long been noted. However, this is one of the first studies to quantify how disparities in clinical measures of chronic disease change under universal coverage.

BOSTON, Mass. (April 20, 2009) — Health care disparities in the U.S. have long been noted, with particular attention paid to the gaps separating racial and economic groups. And while some research has looked at how insurance—and lack of insurance—contributes to this imbalance, few, if any, studies have quantified the impact of universal coverage on differences in health outcomes between these groups.

J. Michael McWilliams
Dr. J. Michael McWilliams

Now, by analyzing measures of blood pressure, cholesterol and blood sugar collected between 1999 and 2006 from the National Health and Nutrition Examination Survey (NHANES), a team of researchers in Harvard Medical School's department of health care policy has compared the health outcomes of individuals by race, ethnicity and education. What's more, the researchers studied whether overall discrepancies between these demographic groups were narrowed among adults with Medicare coverage after age 65.

Looking at data for more than 6,000 individuals between the ages of 40 and 85, researchers probed important indicators of disease control for hypertension, diabetes and coronary heart disease. They found that while health indicators improved for all groups between 1999 and 2006, the socio-demographic gaps remained unchanged or, in some cases, widened. However, among individuals age 65 and older who were eligible for Medicare, a federal social insurance program, the gaps narrowed substantially.

These findings are reported in the April 21 issue of the Annals of Internal Medicine and are funded by The Commonwealth Fund, a private foundation supporting independent research on health policy reform and a high performance health system.

"The tide is rising and it is lifting all boats, but many are still left behind," says lead author J. Michael McWilliams, HMS assistant professor of health care policy and an associate physician in the Division of General Medicine at Brigham and Women’s Hospital. "In addition to quality improvement efforts, we will likely need universal coverage to achieve good control for all adults with these conditions."

The researchers noted that controlling blood pressure, cholesterol and blood sugar are critical steps to prevent devastating complications of cardiovascular disease and diabetes, such as heart attacks, strokes, kidney disease and premature death. These disease control measures were provided by NHANES, a research program of the National Center for Health Statistics, where clinicians travel to all regions of the United States to examine and provide on-the-spot health evaluations for individuals. All data from this program are publicly available.

The researchers discovered a number of examples where racial, ethnic and socioeconomic gaps closed once individuals were eligible for Medicare. For example:

"We found some important indicators that universal health insurance may reduce persistent disparities we've seen for far too long in Americans from different racial or ethnic groups," says senior author John Ayanian, professor of health care policy at Harvard Medical School, HMS professor of medicine at Brigham and Women's Hospital, and professor of health policy and management at the Harvard School of Public Health.

"The results of this study make it clear that guaranteeing  access to affordable insurance for all Americans is the essential first step toward a high performing health care system and a healthier America," said Commonwealth Fund President Karen Davis. "As our leaders look toward health reform it is critical that they take into account the value of health care coverage for everyone and assure that all Americans have the ability to obtain insurance for themselves and their families."

Written by David Cameron


Annals of Internal Medicine. 2009: 150:505-515.

"Racial, ethnic and educational differences in control of cardiovascular disease and diabetes in the United States: trends from 1999 to 2006 and effects of Medicare coverage"

McWilliams JM (1,2), Meara E (1), Zaslavsky AM (1), Ayanian JZ (1,2,3)

David Cameron

Harvard Medical School has more than 7,500 full-time faculty working in 11 academic departments located at the School's Boston campus or in one of 47 hospital-based clinical departments at 17 Harvard-affiliated teaching hospitals and research institutes. Those affiliates include Beth Israel Deaconess Medical Center, Brigham and Women's Hospital, Cambridge Health Alliance, Children's Hospital Boston, Dana-Farber Cancer Institute, Forsyth Institute, Harvard Pilgrim Health Care, Hebrew SeniorLife, Joslin Diabetes Center, Judge Baker Children's Center, Massachusetts Eye and Ear Infirmary, Massachusetts General Hospital, McLean Hospital, Mount Auburn Hospital, Schepens Eye Research Institute, Spaulding Rehabilitation Hospital, and VA Boston Healthcare System.