News Release

Aspirin appears to reduce stroke severity

Peer-Reviewed Publication

American Heart Association

DALLAS, – Individuals who had taken at least one aspirin in the week before suffering an ischemic stroke had milder strokes than people who had not taken aspirin, according to a report in the December issue of Stroke: Journal of the American Heart Association.

The study compared stroke severity of aspirin users and nonusers with data from the Trial of Org 10172 in Acute Stroke Treatment (TOAST), a multicenter, randomized, placebo-controlled, double blind clinical trial in which patients were admitted from 1990-1996.

Among patients whose strokes were caused by a blockage of blood flow in the brain (ischemic stroke), researchers compared stroke severity between those who had been taking aspirin and those who had not. Of 1,275 patients in the study, 509 (almost 40 percent) reported aspirin use during the week before their stroke. Researchers found more strokes among the aspirin users, but their severity was significantly lower than strokes among nonusers.

Using the National Institutes of Health Stroke Scale (NIHSS), 50.3 percent of aspirin users had mild strokes, compared with 43.0 percent of nonusers; only 9.6 percent of aspirin users had severe strokes, compared with 14.8 percent of nonusers.

On the Supplemental Motor Examination (SME) ranking that measures the severity of muscle weakness in arms and legs, 55.6 percent of aspirin users had mild strokes, compared with 48.7 percent of nonusers; 19.8 percent of aspirin users had severe strokes, compared with 24.0 percent of nonusers.

Several different mechanisms factor in aspirin’s protective effect, say the researchers, including its antiplatelet effect, which may improve blood circulation in brain; its antioxidant properties, which may reduce oxidative tissue damage; or some other possible anti-inflammatory, neuroprotective effect, which at this time is still under investigation.

“Aspirin has a rich pharmacology, some of which is still being elucidated,” says primary researcher Janet L. Wilterdink, M.D., of the department of neurology at Brown Medical School in Providence, R.I. “I believe that a combination of all these mechanisms has the potential to play a significant role in aspirin’s beneficial effect.”

In the study, stroke severity was analyzed with two clinical neurological rating scales measuring stroke deficit at trial entry within 24 hours of stroke and again at three months. Aspirin use was defined as self-report of any use at all within seven days before stroke. Various demographic and clinical characteristics and categories of stroke subtypes were also compared between the groups, and results were adjusted for gender, race, age, and various medical conditions such as cardiac history and atherosclerosis risk factors.

No information was collected about the amount or frequency of aspirin use, nor was information collected about the use of any other antiplatelet therapy or warfarin, an anticoagulant drug that inhibits platelet aggregation by interfering with blood-clotting proteins. Further, numerous factors that influence aspirin use also correlate with stroke severity; these factors may include age and prior cerebrovascular or cardiovascular history. These patients may also have received more medical attention and been more aggressively pursuing risk factor reduction.

“Confounding factors such as these may play a large role in this study,” Wilterdink says. “We did collect a lot of information about the relative prevalence of confounding factors and controlled for them in the analysis. However, since the study was not a randomized controlled trial per se, the risk of bias is significant.

Nonetheless, because there is an excellent rationale for aspirin’s benefit in reducing stroke severity, it seems more likely than not that the effect is real.” Because aspirin in widely known to be effective, Wilterdink doesn’t feel further research will compare aspirin to placebo.

“However, future studies looking at other agents in stroke prevention should measure stroke severity as well as frequency in order to obtain the best measure of the agent’s efficacy,” she says.

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The TOAST investigators included Janet L. Wilterdink, M.D.; Birgitte Bendixen, M.D.; Harold P. Adams, Jr., M.D.; Robert F. Woolson, Ph.D.; William R. Clarke, Ph.D.; and Michael D. Hansen, MS. The work was funded in part by the National Institutes of Health.

CONTACT: For journal copies only, please call: 214-706-1396 For other information, call: Carole Bullock: 214-706-1279 or Bridgette McNeill: 214-706-1135


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