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Antiplatelet therapy for acute ischaemic stroke

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Abstract

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Background

In patients with acute ischaemic stroke, platelets become activated. Antiplatelet therapy might reduce the volume of brain damaged by ischaemia and reduce the risk of early recurrent ischaemic stroke. This might reduce the risk of early death and improve long‐term outcome in survivors. However, antiplatelet therapy might also increase the risk of fatal or disabling intracranial haemorrhage.

Objectives

To assess the efficacy and safety of antiplatelet therapy in acute ischaemic stroke.

Search methods

We searched the Cochrane Stroke Group Trials Register (last searched June 2007), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2007), MEDLINE (June 1998 to May 2007), and EMBASE (June 1998 to May 2007). In 1998, for a previous version of this review, we searched the register of the Antiplatelet Trialists' Collaboration, MedStrategy and contacted relevant drug companies.

Selection criteria

Randomised trials comparing antiplatelet therapy (started within 14 days of the stroke) with control in patients with definite or presumed ischaemic stroke.

Data collection and analysis

Two review authors independently applied the inclusion criteria and assessed trial quality, and for the included trials, extracted and cross‐checked the data.

Main results

Twelve trials involving 43,041 participants were included. Two trials testing aspirin 160 mg to 300 mg once daily started within 48 hours of onset contributed 94% of the data. The maximum follow up was six months. With treatment, there was a significant decrease in death or dependency at the end of follow up (odds ratio 0.95, 95% confidence interval 0.91 to 0.99). For every 1000 patients treated with aspirin, 13 patients will avoid death or dependency (number needed to treat to benefit: 79). Antiplatelet therapy was associated with a small but definite excess of symptomatic intracranial haemorrhages, but this was more than offset by the reduction of recurrent ischaemic strokes and pulmonary embolus.

Authors' conclusions

Antiplatelet therapy with aspirin 160 mg to 300 mg daily, given orally (or by nasogastric tube or per rectum in patients who cannot swallow), and started within 48 hours of onset of presumed ischaemic stroke reduces the risk of early recurrent ischaemic stroke without a major risk of early haemorrhagic complications and improves long‐term outcome.

PICOs

Population
Intervention
Comparison
Outcome

The PICO model is widely used and taught in evidence-based health care as a strategy for formulating questions and search strategies and for characterizing clinical studies or meta-analyses. PICO stands for four different potential components of a clinical question: Patient, Population or Problem; Intervention; Comparison; Outcome.

See more on using PICO in the Cochrane Handbook.

Plain language summary

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Antiplatelet therapy for acute ischaemic stroke

Most strokes are caused by a sudden blockage of an artery in the brain (called an ischaemic stroke) that is usually due to a blood clot. Immediate treatment with antiplatelet drugs such as aspirin may prevent new clots from forming and hence improve recovery after stroke. However antiplatelet drugs may also cause bleeding in the brain which could offset any benefits. This review of 12 trials, including 43,041 participants, showed very clearly that aspirin, at a dose of 160 mg to 300 mg daily, started within 48 hours of the onset of stroke symptoms, saved lives and reduced the risk of further stroke occurring in the first two weeks. Aspirin also increased the chances of being alive and independent and improved the chances of making a complete recovery from this stroke. The risk of serious bleeding was very low. Almost of all the evidence in this review comes from trials of aspirin. There is no reliable evidence on the effects of other antiplatelet drugs in acute stroke.