TUESDAY, May 8, 2007 (HealthDay News) -- Off-label, untested use of drug-coated stents makes up almost half of all uses of these devices for doctors treating blocked coronary arteries, a new study reveals.
However, even though the risk for complications is higher with off-label use, the absolute rate for patients is still low overall, researchers say.
"It's very reassuring, because it shows that even though drug-eluting stents are being used almost 50 percent of the time in untested situations, the absolute event rates for both safety and efficacy are very low," said Dr. Charles Davidson, co-author of the paper and director of the cardiac catheterization laboratory at Northwestern Memorial Hospital, Chicago.
His group's paper is published in the May 9 Journal of the American Medical Association, as does a second study finding that off-label use of stents carries about double the risk of complications as approved, on-label use.
Stents are tiny mesh scaffolds used to prop open an artery after balloon angioplasty. Newer -- and more expensive -- drug-coated (or "eluting") stents are supposed to lower the risk of restenosis (re-blocking) of the vessel, something that's often seen with conventional bare-metal stents.
A U.S. Food and Drug Administration advisory committee recently raised concerns about the off-label use of stents. Off-label means that the device is used outside of the specific indications for which it was approved. For stents, typical off-label indications include the use of stents for restenosis, bypass graft lesions and long lesions.
"The FDA raised these concerns at the last panel meeting and sent a little bit of a shock wave off to everybody," Davidson said. "We didn't have any good data on off-label and untested use."
For the first study, Davidson and colleagues analyzed data on 7,752 patients who underwent percutaneous coronary intervention (PCI, or balloon angioplasty) at 140 U.S. hospitals during the first half of 2005.
Stents were used off-label or for untested applications 47 percent of the time. The risk of death, heart attack or a stent-linked thrombosis (clot) while the patient was still in the hospital was similar, regardless of whether the stent was used off-label or not.
However, by 30 days, those in the off-label group had double the risk of experiencing one of these dangerous outcomes. However, this boost in risk was largely explained by the types of patients involved, the researchers said.
"The rates of heart attack and death were under one percent," Davidson explained. "That's double what's seen in the on-label group. But most of the risk could be explained by the clinical characteristics of the patients. The complexity of the patient, not the use of the stent itself, dictated the higher event rate."
"You're dealing with the doubling of the rate, but the absolute number remains well below anything we had before," Davidson said. His conclusion: "It's safe and effective."
Another expert agreed that tougher cases do bring higher risks.
"You don't have to be a rocket scientist to know more complicated lesions have a higher event rate," added Dr. Samin Sharma, director of interventional cardiology at Mount Sinai Medical Center in New York City. "We always knew that once you go to more complex cases, you would have more problems. That is the nature of the disease and the nature of the interventional procedure."
In the second study, a team from Baylor College of Medicine, Houston, looked at more than 3,300 high-risk patients who had received at least one drug-eluting stent at one of 42 different hospitals throughout the United States.
In this case, more than half (54.7 percent) of the patients had at least one off-label characteristic. Such high-risk patients are generally not included in clinical trials used as the basis for FDA approvals.
Participants in the off-label group experienced double the complications (mostly heart attacks) compared to those in the on-label group (10.9 percent vs. 5 percent). At the one-year mark, however, the researchers found no difference in the death rate between the two groups.
The authors urged caution when extrapolating the benefits of drug-eluting stents to more high-risk situations.
There's more on stents at the American Heart Association.