Randomised double-blind placebo-controlled trial of aspirin in primary prevention of CVD events or dementia in the aged.

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The single most important risk factor for cardiovascular disease is age. All men aged 75 years have a 10-15% risk of having a stroke or heart attack in the next 5 years. Low dose aspirin has been shown to prevent further strokes and heart attacks in people who have already had one. It has been also shown to protect people who have not had a heart attack or stroke but who are at increased risk. Given that the elderly are at increased risk why do we need to do a trial in this particular group? The reason is that relatively few elderly patients were included in the previous prevention trials. Also while the elderly may have the most to gain from treatment, they also have the most to lose because they are more likely to suffer from side-effects. Aspirin prevents heart attacks by stopping clots forming in blood vessels. This also means that people taking it have an increased tendency to bleed. Thus though it may prevent strokes due to clots it may also increase the risk of strokes caused by bleeding. Bleeding from the gut is another major problem as aspirin tends to erode the lining of the stomach. Minor bleeding from the gut can also lower blood oxygen carrying capacity which may exacerbate other diseases associated with ageing, e.g. heart failure. Dementia may be caused by repeated clots in small or large vessels. Dementia is a particular problem in the elderly affecting 10% of 85 year olds. It is a major cause of loss of quality of life and a significant cost to the community. Aspirin may reduce the progression of such a disease leading to a maintained quality of life (QOL) for individuals and their families. As our age increases our years of life remaining decreases. This is self-evident. Thus the potential to add years to life reduces and the potential of diseases to adversely affect quality of life becomes more important. Thus it may be more important to prevent a nonfatal stroke that leads to institutionalisation than a fatal stroke. Hence QOL will be assessed.