Should everyone over 50 be taking aspirin?

For and against: Aspirin for everyone over 50? BMJ Volume 330, pp 1440-3

Experts go head to head in this week’s BMJ over whether everyone over 50 should take a daily aspirin to reduce their risk of heart attacks and strokes. Peter Elwood and colleagues at Cardiff University believe that the evidence now supports more widespread use of aspirin, and there needs to be a strategy to inform the public and enable older people to make their own decision.

As a general rule, daily aspirin is given only to people whose five year risk of a vascular event, such as a heart attack or stroke, is 3% or more. The authors show that, by age 50, 80% of men and 50% of women reach this level of risk and they suggest that 90-95% of the population could take low dose aspirin without problems. Evidence is also growing that regular aspirin may reduce cancer and dementia.

“The possibility that a simple, daily, inexpensive low dose pill would achieve a reduction in vascular events, and might achieve reductions in cancer and dementia without the need for screening, deserves serious consideration,” they write. “Although we judge that aspirin should be taken from around 50 years, we insist that the general public should be well informed and the final decision should lie with each person.”

But Colin Baigent of the Oxford Radcliffe Infirmary warns that it would be unwise to adopt such a policy, whatever age threshold is chosen, until we are sure that older patients will derive net benefit from it.

Based on data for 55-59 year olds, aspirin prevents around two first heart attacks per 1000 population each year. However, this benefit does not outweigh the expected risk of a major gastrointestinal bleed at age 60 (1-2 per 1000 per year).

“In my view, we should not contemplate an age threshold approach to primary prevention with aspirin until we have much better evidence of its benefits in older people,” he says. We therefore need further randomised trials comparing low dose aspirin with placebo.

“A recommendation that aspirin be used for primary prevention of vascular disease in unselected people over a certain age could result in net harm, and we must have very good evidence to the contrary before instituting such a policy,” he concludes.