Warfarin works better than aspirin in preventing stroke in older patients with arrhythmia, a multicenter study of nearly 1,000 people in England shows. The researchers randomized 973 patients aged 75 and over (average age 81) with atrial fibrillation to receive either warfarin or aspirin (75 mg daily) and followed them for nearly three years. They found 21 strokes, two hemorrhages, and one systemic embolus in the warfarin group, whereas the aspirin group suffered 48 similarly serious events. Warfarin also caused no more side effects than aspirin.

The researchers said that different doses of aspirin have different effects in atrial fibrillation trials, so a higher dose of aspirin would probably not have been any more effective in preventing stroke, whereas it would likely have increased hemorrhage rates. “Our results show that warfarin can safely be used much more widely in this age group,” the investigators concluded. “They lend support to the use of anticoagulation for all people over age 75 who have atrial fibrillation. The target INR should be in the range of 2.0-3.0” (Lancet. 2007:370:493-503).