Aspirin is a commonly used painkiller, but it has other purported benefits too. One thing it does is reduce the tendency for blood particles called platelets to stick together. This reduces the tendency for blood clots to form. Many ‘cardiovascular events’ such as heart attacks and strokes are finally provoked by the formation of tiny blood clots called ‘thrombi’ (pronounced throm-bye), and aspirin therefore is often recommended for the prevention of these events.
But it’s not all sweetness and light with aspirin because this drug also has the potential for adverse effects too, and in particular the ability to induce bleeding in the lining of the gut.
A recent review in the Archives of Internal Medicine set about assessing the impact of aspirin on not just cardiovascular events, but risk of bleeding too . The review took data from 9 studies in which aspirin was used in dosages ranging from 75 mg to 500 mg per day. In total, the studies involved over 100,000 people, and the average duration of the studies was 6 years.
The populations studied in the individual studies were free from known cardiovascular disease at the start (so-called ‘primary prevention’).
This review revealed that compared to placebo, aspirin:
- Reduced the risk of cardiovascular events (e.g. heart attacks and stroke, fatal and non-fatal) by 10 per cent.
- Did not reduce the risk of death from cardiovascular disease.
- Increased the risk of bleeding by 70 per cent.
- Increased the risk of ‘nontrivial’ bleeding by 31 per cent.
- Did not clearly reduce the overall risk of death.
The authors of this study conclude that ‘… routine use of aspirin for primary prevention is not warranted and treatment decisions need to be considered on a case-by-case basis.’
It’s likely that aspirin has some value for some people in terms of overall disease prevention and perhaps life extension. What this latest review suggests, however, that our faith in aspirin as a preventive medication is largely misplaced.
1. Seshasai SRK, et al. Effect of aspirin on vascular and nonvascular outcomes. Arch Intern Med 9 Jan 2012 [epub ahead of print]