News Release

Gender and geography increase racial disparities in health care, Dartmouth study shows

Peer-Reviewed Publication

The Geisel School of Medicine at Dartmouth

LEBANON, NH -- Past studies have shown racial disparities in health care treatment around the U.S., but new Dartmouth research published in the October 2nd edition of the New England Journal of Medicine shows that the disparities are even larger when geography and gender are added to the equation.

Looking at the most commonly performed joint replacement surgery - total knee replacements - researchers from Dartmouth Medical School and Dartmouth-Hitchcock Medical Center found widely varying rates of surgery among blacks, whites, and Hispanics.

Surprisingly though, they found that gender and geographic location seem to have a major impact on rates, even within the same racial or ethnic group. For example, in Columbia, S.C., New York City, and Los Angeles, rates of knee replacement were equal or even somewhat higher among African-American women. But among black men in the same cities, rates of knee replacement were about half the rates of white men, or even less. Indeed, in Memphis, rates for black men were less than one-third the rate for white men, and were even very low among black women relative to white women.

"We know that knee replacements are a more common operation for women than for men," says James Weinstein, D.O., M.S., one of the authors of the article. "But even adjusting for that, the differences in the rates for black men and black women in the same cities are dramatic. Where a black woman in Los Angeles is just as likely to have this operation as a white woman, a black man's likelihood of having the procedure is half that of his white counterpart in the same city."

Looking at Medicare statistics from 1998-2000, Weinstein and fellow authors Jonathan Skinner, Ph.D., Scott Sporer, M.D., and John Wennberg, M.D., M.P.H were able to analyze data from 430,726 knee arthroplasties according to region, sex, race, and ethnic group.

"This is the most common joint replacement procedure done in this country," Weinstein said. "It is highly effective, it corrects a highly painful condition, and the number of procedures has increased 120 percent in the last 10 years. We know blacks have more degenerative disease than whites and we know that of the 70 million Americans who have arthritis and chronic joint pain, 32 percent are black. And yet, in every region of this country, black males are far below the norm for having this surgery."

"There was remarkable variation in knee replacement rates across regions as well," said Skinner. "An important message of this study is that disparities exist not just because the color of your skin or the language you speak, but also because of your zip code." Even among white women, rates ranged from 2.0 per thousand in New York City to 7.2 per thousand in St. Louis.

In other findings, the article notes than nationally, rates of knee replacement were higher for whites overall than for Hispanics, with the gap most pronounced when looking at rates among men. Some of this gap could be explained by differences in income, and by patterns of residential segregation.

In an accompanying editorial, Risa Lavizzo-Mourey, M.D. and James R. Knickman, Ph.D. of the Robert Wood Johnson Foundation call the study an important step in expanding our understanding of the disparities in treatment patterns: "This research confirms the findings from the recent report by the Institute of Medicine entitled Unequal Treatment, not only that racial and ethnic disparities exist, but that the root causes of these disparities are multifactorial. No simple, single explanation can be cited."

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This latest study, funded by the National Institutes of Health (NIH) and the Robert Wood Johnson Foundation, builds on decades of research by Wennberg and his colleagues at the Center for the Evaluative Clinical Sciences at Dartmouth Medical School, aimed at improving the delivery of health care.

Dartmouth-Hitchcock Medical Center brings together the expertise, dedication, and compassion of one of the nation's top hospitals and the scholarship, research, and leadership of one of the nation's oldest and most distinguished medical schools to form New Hampshire's only academic medical center. DHMC comprises Mary Hitchcock Memorial Hospital, the Dartmouth-Hitchcock Clinic, Dartmouth Medical School and the Veterans Affairs Medical Center in White River Junction, VT.


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