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Deciding whether to take aspirin for primary cardiovascular (CV) prevention can be vexing for patients. Investigators published an updated meta-analysis with useful estimates of CV outcomes, mortality, and adverse effects for this prevention strategy.
The researchers identified 15 randomized trials that compared aspirin with a control for primary prevention, had at least 1 year of follow-up, and focused on clinical outcomes. The trials covered 165,502 patients (weighted mean follow-up, 6.4 years).
Aspirin, compared with control, did not reduce the risk for death (4.75% and 4.82%) or CV death. Aspirin was associated with a lower risk for myocardial infarction (MI; 2.07% vs. 2.35%), but aspirin and control did not significantly differ in risks for fatal MI, coronary revascularization, angina, or symptomatic peripheral arterial disease. Overall stroke rates were similar in both groups, but the aspirin group had a lower rate of ischemic stroke than the control group (1.29% vs. 1.49%) and a nonsignificant trend toward an increase in hemorrhagic strokes (0.29% and 0.23%). The risk for major bleeding was significantly higher with aspirin than control (1.47% vs. 1.02%). Aspirin was not associated with cancer incidence or mortality.
Abdelaziz HK et al. Aspirin for primary prevention of cardiovascular events. J Am Coll Cardiol 2019 Jun 18; 73:2915. (https://doi.org/10.1016/j.jacc.2019.03.501)
Pignone M.What is so hard about aspirin for primary prevention? J Am Coll Cardiol 2019 Jun 18; 73:2930. (https://doi.org/10.1016/j.jacc.2019.03.502)
Comment
This meta-analysis provides estimates of the trade-offs with aspirin for the primary prevention of CV disease. The number needed to treat to prevent 1 MI is 357; for nonfatal MI, 400; and for ischemic stroke, 500. The number needed to harm to cause 1 bleeding event is 222; for intracranial bleeding, 1000. Benefits and risks differ among individuals, particularly by baseline risks, but aspirin for primary prevention is not a winning strategy overall.