Abstract 16394: Aspirin for the Prevention of Cardiovascular Events in Patients without Clinical Cardiovascular Disease: a Meta-Analysis of Randomized Trials
Background: The benefit of aspirin to prevent cardiovascular events in subjects without clinical cardiovascular disease (CVD) relative to the increased risk of bleeding is uncertain. Our aim was to investigate the benefit and risk of aspirin in patients without clinical CVD.
Methods: A meta-analysis of randomized trials of aspirin versus placebo/control to assess the effect of aspirin on major cardiovascular events (MCE) consisting of non-fatal myocardial infarction (MI), non-fatal stroke, or cardiovascular death, all MI, all stroke, all-cause mortality, stroke subtype, and major bleeding. Nine trials involving a total of 102,621 patients were included, 52,145 patients allocated to aspirin and 50,476 to placebo or control.
Results: Over a mean-follow-up of 6.9 years, aspirin was associated with a reduction in MCE (risk ratio [RR] 0.90, 95% confidence interval [CI] 0.85–0.96, P<0.001). There was no significant reduction for MI, stroke, ischemic stroke, or all-cause mortality. Aspirin was associated with hemorrhagic stroke (RR 1.35, 95% CI 1.01–1.81, P=0.04) and major bleeding (RR 1.62, 95% CI 1.31–2.00, P<0.001. In meta-regression, the benefits and bleeding risks of aspirin were independent of baseline cardiovascular risk, background therapy, age, sex, and aspirin dose. The number needed to treat to prevent 1 MCE over a mean follow-up of 6.9 years was 253 (95% CI 163–568) which was offset by the number needed to harm to cause 1 major bleed of 261 (95% CI 182–476).
Conclusions: In conclusion, the current totality of evidence provides only modest support for a benefit of aspirin in patients without clinical cardiovascular disease, which is offset by its risk. For every 1000 subjects treated with aspirin over a 5-year period, aspirin would prevent 2.9 MCE and cause 2.8 major bleeds.
- © 2010 by American Heart Association, Inc.