* Stent meant to unblock arteries in brain
* NIH-funded study showed it did more harm than drugs
* Watchdog group calls for withdrawal
* FDA advisers to discuss stent on Friday
By Anna Yukhananov
WASHINGTON, March 21 (Reuters) - U.S. regulators on Wednesday questioned whether they should ask Stryker Corp to conduct further trials of a stent used to unblock arteries in the brain, after a government-funded study showed the device did more harm than good.
The stent, called the Wingspan system, has been on the market since 2005 and is used to open blocked arteries in the brain when clot-dissolving drugs do not work. It is supposed to improve blood flow and prevent people who have already had a stroke from having another one.
But a study published in the New England Journal of Medicine in September and funded by the National Institutes of Health (NIH) showed the stent may actually do more harm than treating the problems with drugs and lifestyle changes.
Public Citizen, a watchdog group, in December asked the U.S. Food and Drug Administration to withdraw the stent from the market.
A panel of outside advisers to the FDA will meet on Friday to discuss whether Stryker should perform more studies on the stent, or whether there is enough evidence to support its benefit.
The FDA will make a final decision later, taking into account the advisers' recommendation.
Blocked brain arteries caused by the build-up of fatty deposits called plaque account for more than 50,000 of the 795,000 strokes occurring in the United States each year.
Stroke is the fourth-leading cause of death and a leading cause of disability in the United States.
The self-expanding Wingspan device is the only system currently approved by the FDA for certain high-risk stroke patients.
In documents posted online on Wednesday before the panel meeting, FDA reviewers said the NIH-funded study was the first randomized trial that compared the Wingspan stent with a control, and showed in most cases the stent was worse.
Researchers studied 451 patients in 50 U.S. medical centers who had recently had a stroke or stroke-like symptoms caused by narrowing of a major brain artery. Stroke patients who were treated with drugs and the brain stent had more than twice the rate of strokes and death in the month after surgery compared with those treated with drugs alone.
However, FDA staff said the NIH-funded study looked at a broader population than the stent's original target market. When the FDA analyzed a narrower population, there was no difference between the stent and anti-clotting drugs.
The FDA originally approved the Wingspan stent under a Humanitarian Device Exemption (HDE), meaning the agency allows a medical device to be sold without requiring stringent evidence of effectiveness. To qualify, the device must address a rare disease or condition, and show "probable" benefit.
The trial supporting approval of Wingspan enrolled 45 patients who had a stroke caused by a blocked blood vessel in the brain and whose medical treatment failed to prevent another stroke.
Stryker Corp bought Wingspan as part of its acquisition of Boston Scientific Corp's neurovascular business in 2010.
Stryker shares were up 0.1 percent at $54.89 on Wednesday afternoon on the New York Stock Exchange.