Key result
In patients following ischaemic stroke or TIA, aspirin reduced the risk of the composite of non-fatal stroke, non-fatal MI, and vascular death (RR 0.87; 95% CI 0.81-0.94).
Why the study?
Does aspirin reduce the composite of vascular death, myocardial infarction, and stroke in patients following ischaemic stroke or transient ischaemic attack?
Meta-Analysis (n=9,168)
Does aspirin reduce the composite of vascular death, myocardial infarction, and stroke in patients following ischaemic stroke or transient ischaemic attack?
Relative Risk: 0.87 (95% CI 0.81–0.94)
In patients with prior ischemic stroke or TIA, aspirin reduces non-fatal stroke and MI but not vascular death, suggesting that reporting individual outcomes is more accurate than using a composite endpoint.
Reinforces aspirin for secondary prevention after ischemic stroke or TIA; challenges composite endpoints when components differ in effect.
BACKGROUND: Aspirin has been reported to be less effective for secondary vascular prevention in patients with ischaemic stroke, compared with other high-risk populations. This contention is largely based on results of meta-analyses that used a composite outcome of vascular death, myocardial infarction and stroke, reporting a 13% relative risk reduction. In this study, we explore whether the summary relative risk reduction for this composite outcome is representative of estimates for each of the individual components of the composite. STUDY SELECTION: All randomised controlled trials comparing aspirin with placebo/control in patients following ischaemic stroke or transient ischaemic attack, beyond the acute period (2 weeks). DATA ANALYSIS: A fixed-effects model was used and summary risk ratios were calculated for each of the outcomes: vascular mortality, recurrent non-fatal stroke, non-fatal myocardial infarction, composite of the latter three outcomes, all-cause mortality and non-vascular mortality. RESULTS: Ten trials (n = 9,168) were included. For the composite of non-fatal stroke, non-fatal myocardial infarction and vascular death, aspirin was associated with a 13% reduction in risk (risk ratio, RR: 0.87; 95% CI: 0.81-0.94). For individual components of the composite, aspirin reduced the risk of non-fatal ischaemic stroke (RR: 0.81; 95% CI: 0.72-0.90) and non-fatal myocardial infarction (RR: 0.68; 95% CI: 0.52-0.87), but not vascular death (RR: 0.97; 95% CI: 0.86-1.1). Aspirin did reduce the risk of non-vascular death (RR: 0.79; 95% CI: 0.66-0.95), though, and had a trend towards a reduced risk of all-cause mortality (RR: 0.91; 95% CI: 0.81-1.01). CONCLUSIONS: Following ischaemic stroke, aspirin does not reduce the risk of vascular death, but provides a significant reduction in non-fatal stroke, myocardial infarction and non-vascular death. Our findings would support presenting the effect of aspirin therapy on individual outcomes rather than a composite including vascular death.
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McGrath et al. (2011) conducted a meta-analysis in ischaemic stroke or transient ischaemic attack (n=9,168). Aspirin vs. placebo/control was evaluated on composite of non-fatal stroke, non-fatal myocardial infarction and vascular death (RR 0.87, 95% CI 0.81-0.94). In patients following ischaemic stroke or TIA, aspirin reduced the risk of the composite of non-fatal stroke, non-fatal MI, and vascular death (RR 0.87; 95% CI 0.81-0.94).
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