Aspirin associated with fewer CV events, more major bleeding in healthy patients, review finds
When weighing the risks and benefits of aspirin for primary cardiovascular (CV) prevention in individual patients, clinicians must also consider other interventions that may lower risk, an accompanying editorial said.
For patients without cardiovascular (CV) disease, the use of aspirin for primary prevention was associated with a lower risk of CV events and an increased risk of major bleeding events compared to no aspirin, a recent systematic review and meta-analysis found.
The review included randomized clinical trials that each enrolled at least 1,000 participants with no known CV disease and compared aspirin use with no aspirin, with a follow-up of at least 12 months. The primary CV outcome was a composite of CV mortality, nonfatal myocardial infarction, and nonfatal stroke, while the primary bleeding outcome was any major bleeding, as defined by individual studies.
The 13 included trials randomized a total of 164,225 participants (median age, 62 years; 47% men) and had 1,050,511 participant-years of follow-up. Overall, 30,361 (19%) participants had diabetes, and the median baseline risk of the primary CV outcome was 9.2% (range, 2.6% to 15.9%). Results were published online on Jan. 22 by JAMA.
Aspirin use was associated with significant reductions in the composite CV outcome (57.1 vs. 61.4 events per 10,000 participant-years; hazard ratio, 0.89 [95% CI, 0.84 to 0.95]), an absolute risk reduction of 0.38% (95% CI, 0.20% to 0.55%). The number needed to treat was 265. The use of aspirin was also associated with an increased risk of major bleeding compared to no aspirin (23.1 vs. 16.4 events per 10,000 participant-years; hazard ratio, 1.43 [95% CI, 1.30 to 1.56]), an absolute risk increase of 0.47% (95% CI, 0.34% to 0.62%). The number needed to harm was 210.
The review authors noted limitations, including differences between trials in endpoint definitions and in total daily doses of aspirin (range, 50 to 500 mg), with the majority of studies using doses of 75 to 100 mg. They added that eight of the included trials began randomization more than 20 years ago, before widespread adoption of additional primary CV prevention strategies.
The review and meta-analysis, which included three new trials from 2018, has not materially changed the best estimates for the effects of aspirin on CV events and bleeding, according to an accompanying editorial. Weighing the risks and benefits of aspirin for primary CV prevention continues to be complicated and should involve shared decision making between individual patients and clinicians, the editorialist said.
When considering aspirin use for primary prevention in individual patients, clinicians must also consider other interventions to lower CV risk, such as smoking cessation and control of blood pressure and lipid levels, according to the editorial. “Aspirin remains an important medication for acute management of vascular events; for use after certain procedures; for secondary prevention; and, after careful selection of the right patients, for primary prevention,” the editorialist wrote.