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Review: aspirin reduces vascular events but increases bleeding in primary and secondary prevention

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In primary and secondary prevention, what are the benefits and risks of aspirin?

Review scope

Included studies compared aspirin with no aspirin in primary or secondary prevention. Primary prevention trials had to include ⩾1000 patients who did not have diabetes and were scheduled for ⩾2 years of treatment. Secondary prevention trials included patients with previous myocardial infarction (MI), stroke, or transient cerebral ischaemia. Outcomes were serious vascular events (composite end point of non-fatal MI, stroke, or vascular death) and major extracranial bleeding.

Review methods

Individual patient data meta-analysis of 6 randomised controlled trials (RCTs) (n = 95 456) of primary prevention and 16 RCTs (n = 17 029) of secondary prevention.

Main results

Meta-analysis of primary prevention RCTs showed that aspirin reduced serious vascular events and non-fatal MI but did not reduce stroke or vascular death, and increased major bleeding (table). In secondary prevention, aspirin led to a greater reduction of serious vascular events, MI, …

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  • Source of funding: UK Medical Research Council; British Heart Foundation; Cancer Research UK; European Community Biomed Programme.