By John McKenzie

"Most of us take health care for granted," said lead author Elizabeth McGlynn, and associate director of RAND Health. "This study shows we can't. There is a tremendous gap between what we [know] works and what patients are actually getting. Virtually everyone in this country is at risk for poor care."

And the services studied, she said, are necessities not luxuries.

"These are bread and butter," McGlynn said. "These are the basics of good medical care. It isn't care at the cutting edge. It isn't boutique care."

The quality of care varied considerably according to the medical condition, ranging from 79 percent of recommended care for cataracts among older to people to 11 percent of recommended care for people with alcohol dependence.

In other examples:

   Researchers found that 55 percent of heart attack patients did not get common medications that could reduce their risk of dying.

   More than 75 percent of diabetics were not given semi-annual blood tests by their doctors that could help prevent kidney failure and blindness.

   About 46 percent of patients put on antidepressants never got any follow-up from their doctor to see if the drugs were effective or had any side effects.

So how, many Americans might ask, can a health-care system so expensive, so technologically advanced … be so deficient?

"It's designed to fail, not to work. It's too complicated," said Dr. Donald Berwick, a clinical professor of health-care policy at Harvard Medical School and president of the non-profit Institute for Health Care Improvement.

"Our system," he told ABCNEWS, "is advanced technologically but it's gotten really complicated and we haven't designed it for reliability. It's advanced but not reliable."

Berwick who advises hospitals and health-care systems in the United States and abroad said there are several fundamental problems with the American system.

No Safety Net for Doctors

"There are too many medications and too many treatments available for any one doctor to keep track of," said Berwick. He said what doctors need are computerized check lists.

"Pilots take off using checklists to make sure they're safe. Doctors are supposed to have it all stored in their brains? That doesn't work."

No Medical Cooperation

Many doctors, nurses, and pharmacists also are not sharing enough information with each other, he said.

"If you take a person with a chronic illness, they're going to see five or six doctors in a year," said Berwick. "We don't train doctors how to coordinate with each. We don't create information systems that they share. The patient gets lost, they get dropped between people who really should work together but really don't know how to."

The faulty system exists in part because patients do not have one medical file that follows them wherever they go.

"We have fragmented records," Berwick said. "People have office records, and hospital records, and pharmacy records but there's no single uniform record and certainly not an automated one right now. If we had one it would help a ton."

Another problem is that there is no measurement of the problems, which makes flaws difficult to identify and fix. Researchers say we don't have a habit of tracking and measuring the quality of care in the country at large.

Which is why the RAND study is so unusual, and so unnerving.