Aspirin in Stroke Prevention

Researcher name: 
H.J.M. Barnett, MD

In the 1960s, it was shown by Dr. Fraser Mustard, working at Sunnybrook Hospital in Toronto, that cells in the blood called the platelets which function to produce blood clotting after injury (the good thing), and in the presence of arteriosclerotic disease of the arteries (an unwelcome thing) can be altered by drugs tolerated by human beings. One of these drugs was a preparation used for gout (sulfinpyrazone), and the other was the well-known anti-inflammatory and anti-pain pill aspirin.

In the 1960s, it was shown by Dr. Fraser Mustard, working at Sunnybrook Hospital in Toronto, that cells in the blood called the platelets which function to produce blood clotting after injury (the good thing), and in the presence of arteriosclerotic disease of the arteries (an unwelcome thing) can be altered by drugs tolerated by human beings. One of these drugs was a preparation used for gout (sulfinpyrazone), and the other was the well-known anti-inflammatory and anti-pain pill aspirin.

Because platelets were known to play a part in the symptoms of threatening stroke, and because a large number of strokes are due to clotting or thrombosis inside the arteries leading to the brain, a trial of these drugs in stroke prevention was considered appropriate. The Medical Research Council of Canada provided the funding for what became the first randomized trial to evaluate the use of aspirin in the prevention of vascular disease. It was my job to serve as the Principal Investigator. The statistical and other expertise of McMaster was important in this collaborative effort. Patients were entered from all Canadian medical schools and the results of the benefits of aspirin or of sulfinpyrazone were compared with placebo. When the trial was concluded and published in 1976, it was shown that aspirin prevented stroke. Since that time, 10 more clinical trials of this type have been carried out in North America and Europe and all have confirmed the results of this Canadian observation. In addition, and after the Canadian stroke trial, similar trials were carried out in patients threatened with heart attacks, and they too are known to benefit by this use of aspirin.

Returning to stroke prevention, it can be stated that the risk reduction in stroke-threatened patients treated with aspirin is approximately 25%. Putting it another way, for every 1,000 patients threatened with stroke treated with aspirin for two years, 25 strokes are prevented. The occurrence of a stroke is such a dreadful calamity to a human-being, depriving him/her of the ability to earn a livelihood, and in many instances requiring long-term chronic care in expensive institutions. It is obvious that the economic advantages of stroke prevention are very real.