BOSTON – Startling research from the biggest study ever of American health care quality suggests that Americans – rich, poor, black, white – get roughly equal treatment, but it’s woefully mediocre for all.

“This study shows that health care has equal-opportunity defects,” said Dr. Donald Berwick, who runs the nonprofit Institute for Healthcare Improvement in Cambridge, Mass.

The survey of nearly 7,000 patients, reported today in the New England Journal of Medicine, considered only urban-area dwellers who sought treatment, but it still challenged some stereotypes: These blacks and Hispanics actually got slightly better medical treatment than whites.

While the researchers acknowledged separate evidence that minorities fare worse in some areas of expensive care and suffer more from some conditions than whites, their study found that once in treatment, minorities’ overall care appears similar to that of whites.

“It doesn’t matter who you are. It doesn’t matter whether you’re rich or poor, white or black, insured or uninsured,” the chief author at the Rand Health research institute, in Santa Monica, Calif., Dr. Steven Asch, said. “We all get equally mediocre care.”

The researchers, who included U.S. Veterans Affairs personnel, first published their findings for the general population in June 2003. They reported the breakdown by racial, income, and other social groups today.

They examined medical records and phone interviews from 6,712 randomly picked patients who visited a medical office within a two-year period in 12 metropolitan areas from Boston to Miami to Seattle. The group was not nationally representative but does convey a broad picture of the country’s health care practices.

The survey examined whether people got the highest standard of treatment for 439 measures ranging across common chronic and acute conditions and disease prevention. It looked at whether they got the right tests, drugs, and treatments.

Overall, patients received only 55% of recommended steps for top-quality care – and no group did much better or worse than that.

Blacks and Hispanics as a group each got 58% of the best care, compared to 54% for whites. Those with annual household income over $50,000 got 57%, 4 points more than people from households of less than $15,000. Patients without insurance got 54% of recommended steps, just one point less than those with managed care.

As to gender, women came out slightly ahead with 57%, compared to 52% for men. Young adults did slightly better than the elderly.

There were narrow snapshots of inequality: An insured white woman, for example, got 57% of the best standard of care, while an uninsured black man got just 51%.

“Though we are improving, disparities in health care still exist,” the director of the U.S. Office of Minority Health, Dr. Garth Graham, said.

Dr. Graham, who is black, pointed to other data showing enduring inequality in care, including a large federal study last year. He also said minorities go without treatment more often than whites, and such people are missed entirely by this survey.

Some experts took heart in the relative equality within the survey. “The study did find some reassuring things,” said Dr. Tim Carey, who runs a health service research center at the University of North Carolina-Chapel Hill.

But all health experts interviewed fretted about the uniformly low standard. “Regardless of who you are or what group you’re in, there is a significant gap between the care you deserve and the care you receive,” said Dr. Reed Tuckson, who is black and a vice president of United Health-Group, which runs health plans and sells medical data.

Health experts blame the overall poor care on an overburdened, fragmented system that fails to keep close track of patients with an increasing number of multiple conditions.

Quality specialists said improvements can come with more public reporting of performance, more uniform training, more computerized checks, and more coordination by patients themselves.