While aspirin is known to reduce risks for those who have previously suffered strokes and heart attacks, the evidence of the role of aspirin in the initial prevention of cardiovascular events, is uncertain.
This study looked at the outcomes of trials enrolling more than 1,000 participants with no known history of cardiovascular diseases and which included a follow-up after twelve months. Participants included ones who took aspirin and other who took a placebo or had no treatment at all.
The results showed that:
- Aspirin use was associated with an 11% lower risk of cardiovascular events.
- Approximately 250 patients needed to be treated with aspirin for 5 years to prevent a single heart attack, stroke or cardiovascular death.
- Aspirin use was associated with a 43% of major bleeding events, compared to those who did not take it.
- Approximately one in 200 people treated with aspirin would have a major bleed.
- No effect was seen with aspirin on new cancer diagnoses or deaths.
Lead author, Dr Sean Zheng, Academic Clinical Fellow in Cardiology at King's College London said: "This study demonstrates that there is insufficient evidence to recommend routine aspirin use in the prevention of heart attacks, strokes and cardiovascular deaths in people without cardiovascular disease.
"There has been more uncertainty surrounding what should be done in patients who are at higher risk of cardiovascular disease and in patients with diabetes. This study shows that while cardiovascular events may be reduced in these patients, these benefits are matched by an increased risk of major bleeding events.
"Aspirin use requires discussion between the patient and their physician, with the knowledge that any small potential cardiovascular benefits are weighed up against the real risk of severe bleeding."
Sean L Zheng, Alistair J Roddick.
Association of Aspirin Use for Primary Prevention With Cardiovascular Events and Bleeding Events: A Systematic Review and Meta-analysi.
JAMA. 2019; 321(3):277-287. doi: 10.1001/jama.2018.20578.