DESIGN CONSIDERATIONS FOR THE WARFARIN-ANTIPLATELET RECURRENT STROKE STUDY

The Warfarin-Antiplatelet Recurrent Stroke Study is a multicenter, ran domized, double-blind study comparing warfarin against aspirin in the prevention of recurrent stroke. No patient takes two active medication s or two placebos. Warfarin is used in 2 mg doses sufficient to keep t he international normalized The Warfarin-Antiplatelet Recurrent Stroke Study is a multicenter, randomized, double-blind study comparing warf arin against aspirin in the prevention ration (INR) at 1.4-2.8 while a spirin is given as 325 mg q.id. All patients are treated as if they we re on true warfarin. Blood drawn at the local sites are sent to a sing le laboratory in the USA where the prothrombin time/INRs are determine d. To maintain blinding, the values reaching the local investigator by fax are correct if the patient is truly assigned to warfarin but norm al INR values for patients in the true aspirin arm are falsified by a computer program to mimic those values expected for the dose and durat ion of therapy had the patient actually been on warfarin. The sample s ize planned is > 1,900 patients, enough to detect a 30% reduction in t he frequency of stroke and death in the warfarin group compared with a spirin if differences this large exist.