Women Benefit Less From Clot-Busting Stroke Drug

(HealthDay News) -- Women who suffer strokes are much less likely than men to benefit from treatment with the powerful clot-dissolving drug known as tissue plasminogen activator (tPA), new research suggests.

The biggest such study yet conducted found that while more women survived their stroke after receiving tPA, male patients were more than three times as likely to retain good physical function as measured by a test three months after tPA treatment.

"The most intriguing possibility is that there might be an intrinsic biological difference in the way in which women respond to tPA vs. how men respond to tPA," said Dr. Gary Abrams, an associate professor of neurology at the University of California, San Francisco, and a spokesman for the American Academy of Neurology.

Abrams was not involved in the study, which is published in the March 13 issue of Neurology.
Federal rules mandate that tPA can be used only if treatment starts in the first three hours after a stroke. The drug helps limit brain damage by dissolving clots that block blood flow through arteries.

The trial included almost 1,400 stroke patients, 333 of whom (24 percent) were treated with tPA within three hours.

The study found that 47.5 percent of men getting tPA had good function three months later on a standard measure called the Barthel Index, compared to 30.3 percent of women. On another measure, the Rankin Score, 32.2 percent of men and 23.4 percent of women did well.

"In general, women have worse outcomes than men after a stroke," noted lead researcher Dr. Mitchell S. V. Elkind, an associate professor of neurology at Columbia University, in New York City. "There are potential biological reasons why women may not respond as well as men to tPA. Hormonal factors such as the effects of hormones on blood clots may be the reason."

But Elkind added that, "at this point in time, it is premature to treat women differently [than men] after a stroke. We recommend that women as well as men get to a hospital as quickly as possible and be treated as aggressively, including tPA."

There have been indications that postmenopausal women have higher levels than men of a substance that inhibits tPA activity, Abrams said. "A lot more work would have to be done to prove it, but it is an intriguing thought. But there is conflicting evidence and reasons to believe there are caveats in taking this too far."

The results should also be interpreted cautiously, noted Dr. Edgar J. Kenton III, chair of the American Academy of Neurology's practice committee. "This is the only large trial of the response to tPA in women," he said. "We need more trials proving the point one way or another."

"I don't want this study interpreted to say that women should not get tPA," Kenton stressed. "There are small studies suggesting that with ultra-early treatment -- within one hour -- they do better than men. We need more women in more trials to look at these factors."

Kenton also noted the unusually high percentage of patients in the study who received tPA therapy within the three-hour post-stroke limit recommended by experts.

"Twenty-four percent got tPA within three hours," Kenton noted. "The national average is 5 or 6 percent." The measures used in this trial to get tPA delivered to patients early can and should be applied to everyday practice, he said.

More information
Find out more about tPA at the American Heart Association.