Spotlight on Research for 2004

March 2004 (historical)

Geographic Regions Influence Rates of Knee Replacement

Minorities have knee arthroplasty (total knee replacement) for osteoarthritis at rates lower than whites, and one of the influencing factors is geographic region, according to a study conducted at Dartmouth Medical School, Lebanon, N.H. Although previous research has been done indicating that sex, race and ethnic group are factors in arthroplasty rates, this study, funded in part by the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) and the National Institute on Aging (NIA), reveals that geography is an important variation and should be considered in attempts to understand disparities in health care.

Dartmouth's Jonathan Skinner, Ph.D., and his colleagues, using data provided by the U.S. Department of Health and Human Services' (DHHS) Center for Medicare and Medicaid Services, tracked the incidence of total knee replacements for the Medicare population within U.S. geographic regions. They identified 306 regions, including major cities, as described in the Dartmouth Atlas of Health Care, and looked at whether residents, identified as black, Hispanic or non-Hispanic white, received replacements.

The researchers examined contributing factors that might influence arthroplasty rates: residential segregation, for example, a term that means minority representation in specific neighborhoods is not equal to the regional average. Another was variation in patients' preferences, in this case meaning that some people who might benefit from knee replacement decline surgery. Black patients, for example, had previously reported less confidence in knee replacements than white patients. The researchers also looked at rates of underlying disease and at household income. While all these factors influenced arthroplasty rates, they didn't account for all differences, the scientists concluded, and geographic region remained an important variation.

Dr. Skinner and his colleagues also noted that there were substantial differences within and among regions. For example, the rate of surgery for black women in Greenville, N.C., was double the rate for white women in Manhattan, N.Y. In other regions, the rate for black women was significantly lower than (e.g., in Detroit, Mich., and Dallas, Tex.) or equal to (e.g., in East Long Island, N.Y., and Columbia, S.C.) that for white women. Manhattan also had a higher rate for Hispanic women than for white women, but a lower rate for Hispanic men compared to white men. However, within all geographic regions studied (with the exception of Bronx, N.Y.), arthroplasty rates among black men were significantly lower than rates among white men.

Other institutions collaborating on the research were Dartmouth College, Hanover, N.H., Dartmouth-Hitchcock Medical Center, Lebanon, N.H., and the National Bureau of Economic Research, Cambridge, Mass. NIAMS and NIA are components of the U.S. DHHS' National Institutes of Health.

The mission of the NIAMS is to support research into the causes, treatment, and prevention of arthritis and musculoskeletal and skin diseases, the training of basic and clinical scientists to carry out this research, and the dissemination of information on research progress in these diseases. For more information about NIAMS, call the information clearinghouse at (301) 495-4484 or (877) 22-NIAMS (free call) or visit the NIAMS Web site at

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Skinner J, et al. Racial, ethnic, and geographic disparities in rates of knee arthroplasty among Medicare patients. NEJM 2003; 349(14):1350-1359.