Aspirin vs Warfarin to Reduce Stroke Risk

Aspirin works as well as warfarin and has fewer side effects when used to reduce blood clotting in patients with partial blockage of arteries in the brain, according to a new study.

Both aspirin and warfarin have been used for decades to reduce the risk of stroke in patients with the condition known as intracranial stenosis, but doctors have had no evidence for choosing one therapy over the other. In the new study, called the Warfarin Aspirin Symptomatic Intracranial Disease (WASID) trial, investigators at 59 U.S. medical centers compared warfarin to 1,300 mg per day of aspirin in a total of 569 patients for an average of 1.8 years. All the patients had a greater-than-50% blockage of a major intracranial artery and had experienced a transient ischemic attack (TIA) or nondisabling stroke within 90 days of the start of the study.

Investigators found that about 22% of patients had a subsequent ischemic stroke, brain hemorrhage, or death from other blood-vessel-related causes, regardless of which therapy they received. However, the rates of major hemorrhage and death from all causes were significantly higher in those patients treated with warfarin (8.3% for major hemorrhage and 9.7% for death) than those treated with aspirin (3.2% for hemorrhage and 4.3% for death). Based on these results, enrollment in the trial was terminated earlier than planned because of concern for the safety of patients given warfarin.

"The results of this study are only relevant to people with intracranial stenosis,” explained Dr. Marc I. Chimowitz, of Emory University (Atlanta, GA, USA), who led the trial. Since warfarin is a more expensive and complicated therapy than aspirin, not using warfarin and preventing the bleeding complications associated with it would save more than U.S.$20 million a year in the United States alone, estimated Dr. Chimowitz.

The trial underscored the fact that patients with intracranial stenosis are at particularly high risk for stroke and that better therapies are needed, noted the investigators. Their results were published in the March 31, 2005, issue of The New England Journal of Medicine.






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