Black nursing home residents are more likely than white residents to develop blisters and sores that can eventually lead to muscle and bone damage, according to a new study.

The findings suggest the disparities are mostly the result of differences in care between homes with predominantly black or white patients — and not that individual nursing homes are necessarily providing better care to whites than blacks, researchers said.

"In general, nursing homes are lacking appropriate resources," said study author Yue Li, from the University of Iowa in Iowa City. In homes with more black patients, "the problems are particularly pronounced."

For preventing the blisters and sores, known as pressure ulcers, having enough nurses to keep a close watch on patients may be particularly important, according to the researchers.

These sores generally develop in patients who are bedridden or confined to a wheelchair. They happen when the same patch of skin is always exposed to too much pressure and the tissue begins to break down because it doesn't get enough blood. If they aren't treated, pressure ulcers can deepen and cause damage to bones and muscles.

Li said that previous studies have suggested black residents in nursing homes get more pressure ulcers than white residents. But he and his colleagues wondered if recent efforts at improving the quality of care in nursing homes, led by the Centers for Medicare & Medicaid Services, did anything to address that disparity.

From 2003 to 2008, they followed cases of pressure ulcers that were reported at more than 12,000 nursing homes in the U.S., looking at a sample of about 2.5 million patients who were considered to be at high risk for the sores.

Over that time, the overall rate of pressure ulcers decreased in those patients. However, black residents remained more likely to get sores than white residents.

The chance of having a pressure ulcer fell from about 17 percent to 15 percent in black residents between 2003 and 2008, while in white residents it dropped from 11 percent to 10 percent.

When Li and his colleagues looked more closely at differences between nursing homes, they found that both black and white residents were more likely to get a pressure ulcer at homes that had a higher percentage of black residents than at those that were almost all white.

That could be due to a number of reasons, said Nancy Bergstrom, who co-wrote an editorial accompanying the study in the Journal of the American Medical Association. For example, nursing homes with more black patients might not be as well funded, or they may not have enough staff.

She said that the amount of time nurses spend with patients, and how well those nurses know the procedures for preventing sores — including making sure patients in bed are frequently moved around to redistribute their weight — are key to better outcomes.

While some nursing homes have great nurses that stay on for years, others have very high rates of turnover, she explained.

"Time of staff and training of staff and staff stability in nursing facilities...are very pivotal to improving care," Bergstrom, of the University of Texas Health Science Center in Houston, told Reuters Health. "It's hard to set standards and have good care if there's somebody new all the time."

Differences between black and white nursing home residents have also been reported when it comes to vaccinations, pain treatment and end-of-life care, Li said.

"For nursing home patients, the disparities are widespread," he told Reuters Health. "Pressure ulcers are only one of the important outcomes."

Some differences could be the result of patients' conditions when they come into the nursing home, Bergstrom added. For example, more black patients may be admitted with diabetes, which makes other complications more likely.

Li suggested that rather than just focusing on general improvements in all nursing homes, policymakers should look at how to cut down on disparities between homes.

One strategy, he said, could be rewarding particular facilities that show a lot of improvement in care, even if they still don't have as good a record as others.