In 1978, Ontario researchers led by Dr. Henry Barnett demonstrated that Aspirin can prevent strokes. Five hundred and eighty-five patients with threatened stroke were followed in a randomized clinical trial for an average of 26 months to determine whether aspirin or sulfinpyrazone, singly or in combination, influence the subsequent occurrence of continuing transient ischemic attacks, stroke or death.

Eighty-five subjects went on to stroke, and 42 died. Aspirin reduced the risk of continuing ischemic attacks, stroke or death by 19 per cent and also reduced risk for the “harder,” more important events of stroke or death by 31 per cent, but this effect was sex-dependent: among men, the risk reduction for stroke or death was 48 per cent, whereas no significant trend was observed among women. The researchers concluded that aspirin is an efficacious drug for men with threatened stroke.