What is the clinical evidence from this study?

Study design: Meta-Analysis. Population: Primary prevention of ischemic stroke. Intervention: Aspirin vs. Placebo or no aspirin. Primary outcome: Ischemic stroke (OR 0.83, 95% CI 0.74-0.93, p=0.45).

What does this research mean for the field?

Aspirin use for primary prevention decreases the risk of ischemic stroke but increases the risk of severe bleeding events, resulting in little net protective benefit for both apparently healthy adults and patients with cardiovascular diseases. Novelty: ClaimNovelty.SYNTHESIS. Consensus alignment: ConsensusAlignment.NEUTRAL.

November 17, 2016Open Access

The Benefit and Safety of Aspirin for Primary Prevention of Ischemic Stroke: A Meta-Analysis of Randomized Trials

Key Result

Aspirin use for primary prevention decreased the risk of ischemic stroke (OR 0.83) but increased the risk of severe bleeding events, resulting in little net protective benefit.

Study Design

Type

Meta-Analysis

Structured PICO

Does aspirin reduce ischemic stroke in primary prevention populations?

Population

14 randomized trials evaluating primary prevention of ischemic stroke in apparently healthy adults and patients with cardiovascular diseases

Intervention

Aspirin

Comparator

Non-aspirin use

Outcome

Ischemic strokehard clinical

Aspirin provides little net benefit for primary prevention of ischemic stroke due to the offset by an increased risk of severe bleeding events.

Main Result

Effect estimate: OR 0.83 (95% CI 0.74-0.93)

p-value: p=0.45

Limitations

Only three trials were available to study the benefit and safety of aspirin in patients with cardiovascular diseases, reducing statistical power.
Not all included studies were double-blinded; five were open-label randomized clinical trials.
Most patients from the included studies were of Caucasian descent, limiting confidence when applying the data to other populations.

Abstract

Background: Although aspirin is effective in the secondary prevention of stroke among men and women, its use in primary prevention remains controversial. We conducted a meta-analysis of randomized trials to evaluate the benefit and safety of aspirin for the primary prevention of ischemic stroke. Methods: We searched 3 electronic databases (Medline, the Cochrane Central Register of Controlled Trials, and Embase) for articles published before August1st, 2016. Randomized trials reporting the effect of aspirin on the ischemic stroke and its side effects were included. We synthesized evidence qualitatively and useda fixed-effect model to quantify the effect of aspirin on the primary prevention of stroke when the heterogeneity was low, or else applied the random-effect model. Results: Fourteenrandomized trials were included. Overall, aspirin use was associated with a decreased risk of ischemic stroke compared with non-aspirin use (OR: 0.83, 95% CI: 0.74-0.93, P=0.45). In subgroup analyses, the effect of aspirin on ischemic stroke in apparently healthy adults remained significant (OR: 0.83, 95% confidence interval: 0.74-0.94, I2=22%, P=0.28 ;) while in patients with cardiovascular diseases there was no difference in the risk of ischemic stroke between aspirin and non-aspirin groups (OR: 0.75, 95% confidence interval: 0.44-1.29, P=0.46 ;). As for adverse effects, the prophylactic use of aspirin potentially increased the risk of serious bleeding events in a population of apparently healthy individuals and in patients with previous cardiovascular diseases. Conclusion: This meta-analysis of randomized trialsindicated that both the apparently healthy adults and patients with cardiovascular diseases will derive little protective benefit from aspirin considering the increased risk of severe bleeding events.

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