Inferior qualifications and less access to resources among doctors who treat black patients may contribute to racial disparities in the quality of U.S. health care, authors of a study said on Wednesday.

The study, published in Thursday’s New England Journal of Medicine, found that many of the doctors treating black patients complain they don’t have the resources to adequately care for them.

“The findings paint a picture of two health systems, where physicians treating black patients appear to have less access to important clinical resources and be less well-trained clinically than physicians treating white patients,” said study leader Peter Bach of the Memorial Sloan-Kettering Cancer Center in New York.

Bach and his team found that about a fifth of U.S. doctors - 22 percent - are treating four-fifths of the country’s black population. Moreover, 86 percent of the doctors visited by white patients tended to have advanced training, versus 77 percent of the doctors who tended to treat black patients, the Bach team said.

That may explain why black patients are less likely to be screened for disease than white patients. As a result, when a black person is found to be ill, their illness tends to be at a more advanced stage, Bach said in a telephone interview.

And while 19 percent of the doctors treating whites complained that they could not provide high-quality care because of limited access to hospitals, specialists, or advanced equipment, the rate was nearly 28 percent among the doctors who treated blacks.

“The black patients tend to be clustered around physicians who say more often they face these obstacles,” Bach said.

In an accompanying editorial, Arnold Epstein noted that despite U.S. civil rights gains - for example, higher rates of blacks among college graduates and medical students - much remains to be done.

“The United States is still a society in which racial and ethnic characteristics are strongly associated with socioeconomic class and opportunity,” said Epstein, an associate editor at the Journal.

“The article by Bach ... reminds us that, in health care, integration is not complete and separate is not equal.”

The Bach team’s conclusions came from a telephone survey of 4,355 doctors and an analysis of 150,391 doctor visits by black and whites covered by Medicare.

Although some health experts suspect that doctors treat their black patients differently than white patients, the new findings suggest that geography may better explain racial disparities.

The researchers found that doctors treating blacks tend to be in low-income neighborhoods and provide more charity care. Those doctors also tend to get a higher percentage of their income from Medicaid, a program for the poor.

The differences seem to be a function of geography, said Epstein, noting that the doctors who said they didn’t have access to good care tended to be from the same regions of the country.

“The disparities between the health care received by black patients and that received by white patients seem to reflect the place in which patients seek care, rather than the specific doctor they choose within that place,” said Epstein.