A U.S. senator has asked the head of the Food and Drug Administration whether the agency monitors medical device companies' payments to doctors who are involved in clinical studies of the companies' products.

In a letter to FDA Commissioner Margaret Hamburg sent Friday, Sen. Charles Grassley cites information about Medtronic Inc. that surfaced in a separate inquiry.

That query discovered that of 50 clinical investigators studying Medtronic products, "almost all ... received significant payments" from the Fridley-based medical technology company.

In some cases, doctors also had a "proprietary interest in the product being tested and a financial arrangement where the value of compensation could be influenced by the outcome of the study," Grassley said.

No further details of these arrangements or the names of the individual physicians were offered in the letter.

New medical devices must be approved by the FDA before they can be used to treat patients. The process to approve the most-sophisticated devices usually involves a clinical study to ensure that the product is safe and effective. Doctors typically serve as a study's clinical investigators. Medtronic spokesman Brian Henry says this arrangement "is a cornerstone of the innovation in medical technology."

But Grassley asks in Friday's missive, "Are there financial interests that the FDA would consider too significant a conflict to be appropriate for a clinical investigator to be involved in the study?"

FDA spokesman Dick Thompson said the agency will reply to Grassley's questions "in a timely manner."

A Republican from Iowa who is seeking reelection, Grassley has launched several inquiries in the past few years into the financial relationships between doctors and drug and medical device companies.

Henry said Medtronic enacted a new policy in May that prohibits doctors from serving as an investigator on a randomized clinical trial intended to support regulatory approval of a product for which they would receive royalties.

Med-tech companies like Medtronic rely heavily on the input of doctors not only to develop new products, but also to train their peers on how to use them and to provide feedback on how devices work in the real world.

Janet Moore • 612-673-7752