New York - Uninsured Americans were less likely to get the best treatment for heart troubles than those with insurance in a new study that hints the blame may lie with the quality of physicians who typically treat the uninsured. 

In a group of about 61,000 Americans, researchers found that those without any health insurance were between 6 percent and 12 percent less likely than people with either public or private insurance to be prescribed drugs that are considered standard care for heart disease.

"There is some difference of treatment. It only applies - interestingly enough - to uninsured patients," said the study's senior author Dr. Paul Chan, of Saint Luke's Mid America Heart Institute in Kansas City, Missouri.

In the past, studies found uninsured Americans have worse health outcomes, compared to the insured. They're also less likely to get screenings and preventive care - possibly because they don't often go to a doctor.

Less is known, though, about uninsured people who do go to doctors and whether they receive worse care than insured people.

For the new study, Chan and his colleagues used data from 2009 on 60,814 heart patients at 30 doctors' offices around the U.S.

Of those patients, about 9 percent were uninsured, 71 percent had private insurance, and 20 percent had public insurance, such as Medicare or Medicaid.

The researchers, who published their findings in the Journal of the American College of Cardiology, looked to see which patients received the recommended medications for their heart conditions and whether the treatment they got was linked to their insurance status.

Overall, patients with public or private insurance received about the same number of prescriptions, but the uninsured patients were less likely to be prescribed drugs, compared to the insured patients.

For example, about 73 percent of uninsured patients were prescribed beta-blockers after a heart attack, compared to about 81 percent of privately insured patients. And about 89 percent of uninsured patients received medication for high cholesterol, compared to about 95 percent of privately insured patients.

But those differences seemed to disappear when the researchers took into account where the patients were being treated.

"That seems to suggest that at lot of this is being mediated by the clinics that are seeing lots of uninsured patients. They're underperforming compared to clinics that are seeing insured patients," said Chan.

"It speaks to the idea that the higher the number of uninsured patients in your practice, the more financially unstable it is... and quality goes down," said Dr. Ed Havranek, a cardiologist at the Denver Health Medical Center in Colorado.

Havranek, who wrote a commentary accompanying the new study, told Reuters Health, "If it's just the lack of insurance, it should not affect the physicians' decisions to sit down and prescribe (a drug)." It could be driven by doctors' perceptions of their patients, he said.

Chan added that uninsured people tend to be sicker and their other conditions may take priority over their heart problems.

"Truth be told, when many of these patients come in it's not just cardiovascular disease. It's diabetes, obesity and smoking too," Chan said.

Havranek said the first step to solving the problem is doing what Chan and his colleagues did by shining a light on it, and then finding a practical solution.

"You have to be open to the possibility that you're not doing things accurately or fairly across patient populations," he said.