Effects of Aspirin on Risk and Severity of Early Recurrent Stroke After TIA and Ischemic Stroke

Study Questions:

What is the short-term benefit of aspirin in reducing the risk of recurrent stroke after ischemic stroke or transient ischemic attack (TIA)?

Methods:

The authors pooled individual patient data from stroke secondary prevention trials of aspirin versus control after stroke or TIA. They focused on events during the 12 weeks from randomization. Outcome events included: recurrent ischemic stroke, disabling or fatal recurrent ischemic stroke, any recurrent stroke, any fatal stroke, intracerebral hemorrhage (ICH), and acute myocardial infarction.

Results:

There were 12 trials that included a total of 15,778 subjects included in the study. Aspirin decreased the risk of any ischemic stroke at 0-6 weeks (hazard ratio [HR], 0.42; 95% confidence interval [CI], 0.32-0.55) and 6-12 weeks (HR, 0.60; 95% CI, 0.41-0.86). All outcome events were significantly reduced in the aspirin group compared to the control group at 0-6 weeks and at 6-12 weeks, except any fatal stroke at 6-12 weeks (HR, 0.71; 95% CI, 0.30-1.65). Aspirin reduced the odds of disabling stroke at 2 weeks by 90% (HR, 0.07; 95% CI, 0.02-0.31). Meaningful reductions in the odds of disabling stroke with aspirin were also seen at 6 weeks (HR, 0.19; 95% CI, 0.11-0.34) and 12 weeks (HR, 0.26; 95% CI, 0.17-0.40). There was no increased risk of ICH in the aspirin group. When patients who were enrolled in trials within 7 days of their stroke or TIA were evaluated, aspirin reduced the risk of future stroke in those with mild index strokes or TIAs, but had no impact on the risk of future stroke in those with more severe strokes. The beneficial effects of aspirin were independent of the drug dose, stroke etiology, or patient characteristics.

Conclusions:

The authors concluded that aspirin reduces the risk of early stroke after ischemic stroke or TIA.

Perspective:

Up to 10% of patients have a recurrent stroke after a TIA or minor ischemic stroke. Aspirin can reduce this risk. Observational studies suggested that aspirin reduces the risk and severity of recurrent stroke, but the time course of this benefit had not been well evaluated. The findings from Rothwell et al. suggest that much of aspirin’s beneficial effects in secondary stroke prevention are obtained in the first few weeks to months after the index event. The clinically meaningful reductions in the risk of recurrent stroke (60% reduction in any ischemic stroke at 6 weeks and 90% reduction in disabling ischemic stroke at 2 weeks) shown in this study have public health implications. It reaffirms the message of urgent evaluation after stroke or TIA and shows that much of the benefit of this expedited assessment is due to aspirin administration. Aspirin is inexpensive and readily available, even in resource-poor settings, allowing these results to be generalized. Additionally, it may be reasonable to recommend that patients take aspirin after self-diagnosed TIA, as the risk of ICH in this population is low and the risk of recurrent ischemic stroke is high.

Clinical Topics: Prevention, Vascular Medicine

Keywords: Aspirin, Cerebral Hemorrhage, Cerebral Infarction, Ischemic Attack, Transient, Myocardial Infarction, Myocardial Ischemia, Risk Reduction Behavior, Secondary Prevention, Stroke, Vascular Diseases


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