This study compared aspirin to warfarin to determine optimal therapy for the prevention of recurrent stroke. Both drugs slow clotting of the blood. 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. Numerous previous studies have proven that use of aspirin reduces recurrent stroke by about 25 percent. Part of the controversy about aspirin versus warfarin for stroke prevention has been the thinking among clinicians that warfarin may be a better blood thinner than aspirin to prevent almost all forms of stroke, but that it has greater side effects, increased risk of hemorrhage, and higher costs due to the need for blood tests to monitor the treatment effect for patients.

To make the aspirin and warfarin arms of the study as unbiased as possible, the investigators matched both groups of patients for primary stroke severity, age, gender, education, and race/ethnicity. The two groups were also matched for stroke risk factors, including hypertension, diabetes, cardiac disease, smoking, alcohol consumption, and physical activity. The investigators used an aspirin dose of 325 mg/day and a warfarin dose specifically tailored to each individual patient.

This study found that aspirin works as well as warfarin in helping to prevent recurrent strokes in most patients.