WEDNESDAY, March 7, 2007 (HealthDay News) -- About 60 percent of the drug-coated stents that have become the center of intense controversy are being used in cases not approved by the U.S. Food and Drug Administration, new studies show.
Although this was first reported in early February, the high incidence of so-called "off-label" use is published in a series of studies in the March 8 issue of the New England Journal of Medicine.
The publication of the studies follows reports Monday of a U.S. House committee request for safety data from two key manufacturers of coated stents.
Rep. Henry Waxman, D.-Calif., chairman of the House Oversight and Government Reform Committee, asked Boston Scientific and Johnson & Johnson to provide documents on their stents as part of an investigation into product safety and off-label use, according to news reports.
The coated stents have FDA approval for use in patients with a single blocked artery who do not have any accompanying medical problems, such as diabetes. But the journal studies indicate that many patients are getting several stents, some under emergency conditions, such as following a heart attack, even when there are other medical complications.
Researchers are calling for more studies of the practice of off-label use of stents -- wire, mesh tubes inserted to keep arteries open -- to measure any risks to patients.
"We attended the meeting of the FDA advisory committee in December," said Dr. Gregory D. Curfman, executive editor of the journal. "What we wanted to do is capture the essence of the presentations in manuscript form to give our readers a chance to judge the evidence."
The FDA meeting was held because of reports that patients receiving coated stents had a higher rate of blood clots. But that problem was "a small concern" compared to widespread off-label use, said Dr. Andrew Farb, an FDA medical officer who wrote an accompanying perspective piece in the journal.
The FDA panel said that all patients receiving the drug-coated devices are at heightened risk for blood clots, and that many patients receiving the devices are at risk for heart attacks and death.
But there isn't enough evidence to say if the danger of heart attacks and strokes is due to the devices or the patients' poor health, the panelists added. On-label use is limited to no more than two stents; off-label covers three or more.
Medicare is reviewing whether it will continue to pay for off-label use of the coated stents, Curfman said. "We have no idea what Medicare will do," he said. "Obviously, it would be a major step if they did not reimburse for off-label use."
The newer studies are aimed at heightening awareness of the issue, Farb said. "When you have any type of medical intervention, when you see more complicated patients or lesions, you will see a higher rate of adverse events," he said. "That is what has been observed in these studies. Our goal is to make the medical community at large aware of the issue."
In part because of such findings, "the percentage of drug-eluting stents that are being implanted has declined over the past few months," said Dr. William Maisel, a cardiologist at Beth Israel Deaconess Medical Center in Boston, who wrote another perspective piece for the journal.
Studies are needed to answer questions about off-label use, Maisel said. "Data currently are not sufficient to make a decision," he said. "It is important to make a distinction between something you know to be bad and something you don't know the answer to, and to many off-label uses we don't know the answer," he said.
An FDA statement released after the December meeting "had specific language on off-label use," Farb said. "When patients receive such stents in off-label situations, the results may not be the same as for patients treated with on-label use."
Another pressing issue is that of late thrombosis, or blood clots, in stent recipients, both Maisel and Farb said. Studies show a slight but definite increase of these clots, generally linked to discontinuation of the anti-clotting medications Plavix and aspirin.
"We are collaborating with professional societies on antiplatelet [clot-preventing] therapy," Farb said. "The optimum duration of antiplatelet therapy is unknown, and we need more work on studies of this topic to minimize the risk of stent thrombosis."
Maisel said: "One of the most important questions now being asked in the use of drug-eluting stents is whether the patient is able to take uninterrupted antiplatelet therapy for at least 12 months. Stopping therapy before then can increase risk."
The issue of off-label use of stents is starting to affect medical practice, said Dr. Robert Michler, director of the heart center at Montefiore Medical Center in New York City. "Widespread use in off-label indications has diminished," he said.
"But the full impact has yet to be unraveled because many people are eager to see the data in these articles," Michler said.
The widespread off-label use of drug-coated stents "is an enormous public health concern" he added. "It is extremely important for patients and the medical society to understand this issue."
One major problem is that cardiologists often use stents in cases where "the recommended gold standard therapy is coronary bypass surgery," Michler said.
More information
An introduction is drug-eluting stents is provided by the U.S. Food and Drug Administration.
