Two new studies shed light on some of the differences in osteoarthritis (OA) between African-Americans and whites. They add to an ongoing effort by researchers to explore factors, including race, that may influence how the disease progresses and how to develop more targeted therapies.

The first study, published recently online in Arthritis Care & Research, found blacks are about half as likely to get hip OA as whites. But once they have it, blacks have an equal risk for progression of the disease as whites.

This study also found that blacks are equally likely to develop knee OA as whites, but more than 50 percent more likely to have it progress. The findings are based on analysis of data from the Johnston County Osteoarthritis Project, a long-term study of more than 3,000 black and white residents in rural North Carolina.

“Knowing people are at a higher risk for progression means you need to get early intervention for those folks so [the arthritis] doesn’t progress more,” explains senior study author Joanne M. Jordan, MD, director of the Thurston Arthritis Research Center at the University of North Carolina at Chapel Hill. “They might be targeted for interventions such as weight loss, increased physical activity, enrollment in self-management courses, corrections of malalignment and assessment for assistive devices.”

Dr. Jordan says there are many questions relating to racial differences still to be studied, beginning with the reason for these variances. She says possibilities include weight, anatomical differences (for example, the shape of the joint) and/or occupational, genetic or dietary factors.

The second study, also published online recently in Arthritis Care & Research, surveyed almost 800 people, age 50 or older, with moderate to severe knee OA. Within the survey were questions about a participant’s race, social support network and whether he or she would consider having total knee replacement (TKR) surgery.

Researchers found that blacks were significantly less willing than whites to undergo TKR, which the study authors characterize as an “effective and cost effective intervention” for advanced knee OA. And although blacks reported having less social support than whites – defined, for example, as being less likely to be married – the study found that the lack of social support wasn’t a barrier to them getting TKR surgery. Previous studies have suggested that blacks may instead avoid getting the procedure due to other factors, such as worries about the efficacy and risks of the procedure, and lack of complete trust in their physician’s recommendations.

The study found that social support, however, was an important determinant in whether whites were willing to undergo TKR: The more support they had – through marriage, circle of friends and other relationships – the more amenable they were to having surgery.

Earlier studies have linked greater social support to less depression, less pain and functional limitations due to OA, and better improvements after TKR.

“It gives us some better insight on how patients think and how they differ,” explains lead study author Ernest R. Vina, MD, assistant professor of medicine in the division of rheumatology and clinical immunology at the University of Pittsburgh.

Dr. Vina says it’s important to stress that care still needs to be personalized to individual patients. But he says there is a benefit to better understanding the racial differences that keep patients who need knee replacements from getting them.

“When physicians … treat patients who may be candidates for joint replacement surgery, and when these patients have questions or hesitations, it’s a matter of tailoring your message to patients based on what matters more to them,” Dr. Vina explains.

Other studies have also sought to better understand the reason for racial differences among OA patients. A study presented at the 2012 annual meeting of the American College of Rheumatology in November showed black women have the highest risk of getting knee OA and needing joint replacement surgery, and Hispanic women have higher rates than Caucasian women or men of all races.

Kelli D. Allen, PhD, an associate research professor in internal medicine at Duke University and a research health scientist at Durham VA Medical Center in North Carolina, has studied racial differences in relation to treatment, pain and function among OA patients. She says both of these new studies add to the body of knowledge examining what needs to be done to improve outcomes for patients with OA, given that racial differences are known to exist both in terms of severity and treatment with joint replacement surgery.

“I think we see a lot of continued research on racial differences in OA because people are now looking for factors underlying these differences. This is important for informing potential strategies to mitigate those disparities and moving the field toward effective interventions,” Allen says.

For example, Allen says the second study outlines specific issues that can be addressed to increase the odds that both black and white patients who need a TKR actually get it. By knowing what patients are concerned about, doctors can make sure those with a lack of social support are informed about rehabilitation facilities or home health help, while those worried about the efficacy of the procedure can be educated with research and statistics.  

“Since total joint replacement is effective for many patients with severe and debilitating knee OA, it’s important to make sure that patients considering this procedure have adequate information to make a fully informed decision,” Allen explains. “Inaccurate understanding of risks, benefits, and resources for recovery may sway patients against having a surgery that they may otherwise be interested in pursuing to deal with their OA.”

Dr. Vina agrees and says this area of research is important because there is a wide range of benefits when those who need joint replacements get them. “Osteoarthritis is a very debilitating disease. Pain is chronic in these patients and some patients may benefit from undergoing joint replacement, but choose not to for many different reasons. When they do that, they live not only with pain but also disability. That can lead to certain consequences. They may require more medications, even narcotics and more visits to physicians and hospitals. So it’s not only debilitating but also costly in medicine,” Dr. Vina says.