Key messages from scientific research that's ready to be acted on
Got It, Hide thisMahmoud AN, Gad MM, Elgendy AY, et al. Efficacy and safety of aspirin for primary prevention of cardiovascular events: a meta-analysis and trial sequential analysis of randomized controlled trials. Eur Heart J. 2019;40:607-17.
In people who do not have cardiovascular disease, does aspirin reduce risk for death? Does it increase bleeding events?
Aspirin is often taken by people who have had a heart attack or stroke to prevent these events from happening again. When blood clots form inside the vessels that take blood to your heart or your brain, blood flow is reduced; this can lead to a heart attack or stroke. Aspirin works by reducing your blood’s ability to clot.
For years, doctors have recommended that some older adults who have never had a heart attack or stroke take an aspirin a day to prevent these events. However, aspirin can cause bleeding, and it wasn’t clear if taking aspirin daily causes more harm than good.
This review looks at whether aspirin reduces deaths and increases major bleeding in people who do not have cardiovascular disease (e.g., a history of heart attack, stroke, or blood clots in the arteries in their legs).
The researchers did a systematic review of studies available up to September 2018. They found 11 randomized controlled trials that included 157,248 people with an average age of 61 years. About half of the people in the studies were women.
The key features of the studies were:
Compared with placebo or no treatment, aspirin
In people who do not have cardiovascular disease, aspirin does not reduce risk for death but does increase risk for major bleeding compared with placebo or no aspirin treatment. It is important to recognize that these results do not apply to people who have a history of heart disease or stroke.
Outcomes | Number of trials and people | Rate of events with aspirin | Rate of events with control | Effect of aspirin at an average 6.6 years of follow-up |
Death from any cause | 11 trials (157,248 people) | 4.6% | 4.7% | No difference in effect† |
Death from a cardiovascular cause‡ | 11 trials (157,248 people) | 1.3% | 1.4% | No difference in effect† |
Heart attack | 11 trials (157,248 people) | 1.9% | 2.2% | About 3 fewer people out of 1000 had a heart attack |
Stroke | 11 trials (157,248 people) | 1.7% | 1.8% | No difference in effect† |
Major bleeding | 11 trials (157,248 people) | 1.8% | 1.2% | About 6 more people out of 1000 had a major bleed |
Intracranial bleeding§ | 11 trials (157,248 people) | 0.4% | 0.3% | About 1 more person out of 1000 had an intracranial bleed |