Little Data on Stent’s Most Common Use

By BARNABY FEDER
From 2003 through 2006, more than one million patients suffering from clogged arteries and veins in their torsos and legs received stents that had undergone scant testing for such uses, said Dr. William H. Maisel, a device safety specialist at Harvard Medical School.
The stents are tiny metal scaffolds inserted in blood vessels to improve circulation. But regulators have approved them only for helping to drain digestive fluids from the bile duct in cancer patients. Dr. Maisel said reports to the Food and Drug Administration of problems with the devices, known as biliary stents, suggest that their off-label use in arteries is injuring hundreds and perhaps thousands of patients.
Dr. Maisel said that the biliary stents are probably the best treatment option for many patients receiving them in various arteries but that the lack of rigorously collected data leaves patients and doctors somewhat blind to the extent of the risks and benefits.
“Doctors, professional medical societies, the device companies and the F.D.A. all bear responsibility for this growing problem,” said Dr. Maisel, whose research is summarized in an article he wrote with Dr. Jonathan Bridges, to be published Monday in The American Journal of Therapeutics.
The stents have been approved under a portion of the device regulation that requires minimal testing and supervision. It is common and legal for doctors to use devices or drugs approved for one therapy in other treatments. In the case of the biliary stents, though, the alternative uses are estimated to account for as much as 90 percent of the market. There is little trial data available on their safety and effectiveness in arteries compared with surgical alternatives or drug therapy, and little data compares biliary stents with one another.
Nearly 88 percent of the 561 problems reported to the F.D.A. in 2003-6 involving biliary stents occurred in off-label uses, Dr. Maisel said. It is generally accepted that device malfunctions and injuries occur far more often than they are reported. He said off-label problems were the most likely to go undisclosed because of potential lawsuits.
The market for biliary stents in their approved use was less than $35 million in 2006, according to the market research company Millennium Research, but it has attracted more competitors than the multibillion-dollar market for heart stents — an indication that demand is still growing.
The F.D.A. has expressed concern about such practices in recent years. Last March, it convened a meeting of the device companies to remind them they could not engage in any activity that could be construed as marketing the biliary stents for anything other than their labeled use. And it urged the companies to accelerate investments in trials that could generate the data needed for their approval for use in the circulatory system.
Still, it has continued to approve biliary stents with minimal review, including a new device from Medtronic that the agency cleared for sale in November. The F.D.A. received a copy of the new study Friday, Dr. Maisel said. In an e-mail message, the agency declined to comment.
Some trials focused on use of biliary stents in arteries are under way. For example, the device maker EV3 has trials started in both Europe and the United States for use of its EverFlex biliary stent in a major leg artery.
But it has not yet finished enrolling the 250 patients it seeks for the trial in the United States. Among other things, the trial will track fracture rates — a major vulnerability for stents in the leg — for five years.
“I’m not saying there’s a simple answer here,” Dr. Maisel said, “but no one can stand up and say one million off-label stents is a good thing.”