There is no evidence that brand-name drugs given to treat heart and other cardiovascular conditions work any better than their cheaper generic counterparts, U.S. researchers said on Tuesday.

The findings run counter to the perception by some doctors and patients that pricier brand-name drugs are clinically superior, said Dr. Aaron Kesselheim of Brigham and Women's Hospital and Harvard Medical School in Boston, who led the study.

Kesselheim and colleagues combined the results of 30 studies done since 1984 comparing nine sub-classes of cardiovascular drugs to generic counterparts.

The brand-name drugs did not offer any advantage for patients' clinical outcomes in those studies, they wrote in the Journal of the American Medical Association.

"Brand-name drugs for cardiovascular disease can be as much as a few dollars a pill, whereas generic drugs might be as little as a few cents a pill," Kesselheim said.

"If a patient is prescribed a generic drug because that's what's appropriate for their condition, then they should feel confident taking that drug. And physicians themselves should also feel confident prescribing generic drugs where appropriate," Kesselheim said in a telephone interview.

He said rising costs of brand-name prescription drugs strain the budgets of patients as well as public and private health insurers. Overall U.S. prescription drug sales hit $286.5 billion in 2007.

Pharmaceutical companies retain exclusive rights to drugs they develop for a certain number of years, after which others can sell generic versions that are chemically equivalent. The active ingredient is the same, but the color and shape may differ and they may have different inert binders and fillers.

In the United States, the Food and Drug Administration must approve a generic version of a drug before it can be sold.

Kesselheim said cardiovascular drugs to treat conditions of the heart and blood vessels are the most commonly prescribed category.

The study covered beta-blockers, diuretics, calcium-channel blockers, statins, antiplatelet agents, ACE inhibitors, alpha-blockers, anti-arrhythmic agents and warfarin.

The researchers said brand-name manufacturers have suggested generic drugs may be less effective and less safe. They also found that many editorials in medical journals questioned whether generic drugs were as good.

Generic medications represent 66 percent of the total prescriptions in the United States, but less than 15 percent of the money spent on prescription drugs, according to the Generic Pharmaceutical Association industry group.

Kathleen Jaeger, who heads the pharmaceutical group, said the research reconfirms that FDA-approved generics provide the same medicine with the same clinical effects at a substantial cost savings.

"You have patients worrying about being able to receive and afford quality health care. As everyone is grappling with how to increase access and reduce costs, we know that generics are part of the solution," she said in a telephone interview.

Ken Johnson, senior vice president of the Pharmaceutical Research and Manufacturers of America, or PhRMA, said in a statement, "The contention that brand-name medicines drive up the cost of health care is fatally flawed.

"Without today's innovative brand-name drugs to legally copy, there would be no generic drug industry," he said.