WASHINGTON - With the US healthcare industry under increasing scrutiny over dangerous conflicts of interest, a new study released Wednesday concludes that almost all doctors have some relationship with drug makers.

US and Australian researchers said in the study that 25 percent of doctors surveyed said they had received direct payments from pharmaceutical producers.

In addition, fully 94 percent of practicing doctors "have at least one type of relationship with the drug industry," though this most often means receiving food in the workplace or sample prescription drugs.

"Relationships with industry are a fundamental part of the way medicine is practiced today. The real questions relate to how much is too much and how far is too far," said a summary of the study released Wednesday.

The study, to be published in the April 26 issue of the New England Journal of Medicine, comes in the wake of several scandals in the health and research industries over conflicts of interest.

Last year, for instance, Dr. Trey Sunderland of the US National Institutes of Health was shown to have received 285,000 dollars from Pfizer, the world's largest drug company, for cooperating with them without having informed his superiors at the government health research agency.

The study found that drug and medical device manufacturers single out doctors in certain areas and doctors with influence over others to develop close relationships, offering things like payments for consulting and honoraria for speaking engagements.

Cardiologists are a key target of the industry's consulting and other payments, in part because they can influence what drugs and devices other doctors choose, said lead researcher Eric Campbell of the Institute for Health Policy at Massachusetts General Hospital and Harvard Medical School.

"Cardiology is a highly influential specialty within the medical profession. If the drug and device industry can influence cardiologists, they can likely influence the prescribing practices of other doctors," said Campbell.

"It appears that these relationships benefit physicians and industry, but the important policy question is to what extent do these relationships benefit patients in the terms of the care they receive," he said.

The researchers note that more payments go to doctors who develop clinical guidelines and mentor other doctors in training than to other types of doctors.

"I know it's cliche, but if it didn't work, drug companies wouldn't do it," said David Blumenthal, director of the Institute for Health Policy.

"It appears pretty clear that industry forms tighter relationships with doctors who are really the thought leaders, the ones who are likely to affect the behavior of other doctors," Blumenthal said.

According to the summary, the authors of the study said their findings should "raise alarms" to do more to prevent health manufacturers from having too much influence over doctors.

The study was conducted by researchers at Massachusetts General Hospital-Partners Health Care System, Yale University, and the University of Melbourne and Royal Melbourne Hospital in Australia.

They surveyed 1,662 physicians in anesthesiology, cardiology, family practice, general surgery, internal medicine, and pediatrics over their financial ties with industry, and the reasons behind those ties. - AFP/ra