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Aspirin and risk of hemorrhagic stroke: a meta-analysis of randomized controlled trials
J He1, P K Whelton, B Vu
1Department of Biostatistics and Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA 70112, USA. jhe@mailhost.tcs.tulane.edu
Insights
Aspirin use reduces heart attack and ischemic stroke risk but increases hemorrhagic stroke risk. The benefits of aspirin for cardiovascular prevention may outweigh the increased risk of bleeding in the brain for most individuals.
Area of Science:
- Cardiovascular Medicine
- Neurology
- Pharmacology
Background:
- Aspirin is a common treatment for preventing myocardial infarction and ischemic stroke.
- Concerns exist regarding aspirin's potential to increase the risk of hemorrhagic stroke.
Purpose of the Study:
- To quantify the risk of hemorrhagic stroke associated with aspirin treatment.
Main Methods:
- A systematic review and meta-analysis of randomized controlled trials published in English before July 1997.
- Included trials compared aspirin to a control treatment for at least 1 month with reported stroke subtype incidence.
- Data from 16 trials involving 55,462 participants were analyzed.
Main Results:
- Aspirin significantly reduced the risk of myocardial infarction (137 fewer events per 10,000 person-years) and ischemic stroke (39 fewer events per 10,000 person-years).
- Aspirin treatment was associated with an increased absolute risk of hemorrhagic stroke (12 more events per 10,000 person-years).
- The increased risk of hemorrhagic stroke did not vary based on participant or study design characteristics.
Conclusions:
- Aspirin therapy is linked to an elevated risk of hemorrhagic stroke.
- Despite the increased hemorrhagic stroke risk, the overall benefits of aspirin in preventing myocardial infarction and ischemic stroke may be greater for most populations.
Context:
Aspirin has been widely used to prevent myocardial infarction and ischemic stroke but some studies have suggested it increases risk of hemorrhagic stroke.
Objective:
To estimate the risk of hemorrhagic stroke associated with aspirin treatment.
Data Sources:
Studies were retrieved using MEDLINE (search terms, aspirin, cerebrovascular disorders, and stroke), bibliographies of the articles retrieved, and the authors' reference files.
Study Selection:
All trials published in English-language journals before July 1997 in which participants were randomized to aspirin or a control treatment for at least 1 month and in which the incidence of stroke subtype was reported.
Data Extraction:
Information on country of origin, sample size, duration, study design, aspirin dosage, participant characteristics, and outcomes was abstracted independently by 2 authors who used a standardized protocol.
Data Synthesis:
Data from 16 trials with 55462 participants and 108 hemorrhagic stroke cases were analyzed. The mean dosage of aspirin was 273 mg/d and mean duration of treatment was 37 months. Aspirin use was associated with an absolute risk reduction in myocardial infarction of 137 events per 10000 persons (95% confidence interval [CI], 107-167; P<.001) and in ischemic stroke, a reduction of 39 events per 10000 persons (95% CI, 17-61; P<.001). However, aspirin treatment was also associated with an absolute risk increase in hemorrhagic stroke of 12 events per 10000 persons (95% CI, 5-20; P<.001). This risk did not differ by participant or study design characteristics.
Conclusions:
These results indicate that aspirin therapy increases the risk of hemorrhagic stroke. However, the overall benefit of aspirin use on myocardial infarction and ischemic stroke may outweigh its adverse effects on risk of hemorrhagic stroke in most populations.