Aspirin and Warfarin Equally Effective Against Stroke

The study, sponsored by the U.S. National Institute of Neurological Disorders and Stroke (NINDS), was published in the November 15, 2001, issue of The New England Journal of Medicine.

The study, a seven-year double-blind, randomized clinical trial involving 2,206 patients at 48 participating centers, was the largest trial to date comparing aspirin to warfarin for recurrent stroke prevention. Both drugs slow clotting of the blood, and blood clots are
involved in the final stages of the most common type of stroke due to blockage of the vessels that supply oxygen-rich blood to the brain. Aspirin affects the blood platelets, while warfarin inhibits circulating clotting proteins in the blood.

Aspirin has been used for over 100 years, but its beneficial effects to prevent stroke and heart attack only started to be recognized in the 1970s. Previous studies have shown that use of aspirin reduces recurrent stroke by about 25 %. An earlier trial revealed a distinct benefit of warfarin over aspirin in preventing recurrent stroke in patients whose stroke was related to atrial fibrillation (AF), which occurs in about 15 % of stroke patients.

The investigators used an aspirin dose of 325 mg/day and a warfarin dose specifically
tailored to each individual patient. The study excluded patients with atrial fibrillation, those with a blood clot in the heart, and those eligible for carotid endarterectomy surgery. Several subsets of patients seemed to show slight benefits from one of the two therapies, but neither of the treatments showed a difference greater than would be expected from chance alone. Overall, there were no significant differences between the two drugs.

"This scientifically sound definitive clinical trial provides important information in the fight against stroke,” said John R. Marler, M.D., associate director for clinical trials for the NINDS. "It supports the widespread use of aspirin and other antiplatelet drugs, but it demonstrates an equally efficacious alternative, appropriate for selected patients.”




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