A Cochrane review included 8 studies with approximately 10 000 patients with a history of stroke or transient ischaemic attack (TIA). The lipid-lowering interventions were pravastatin (2 studies), atorvastatin (1 study), simvastatin (2 studies), clofibrate (2 studies), and conjugated oestrogen (1 study). The follow-up ranged from 90 days (1 study) to 6 years. Lipid-lowering therapies had no effect on stroke recurrence (OR 0.92, 95% CI 0.81 to 1.04) but statins alone had a marginal benefit in reducing subsequent cerebrovascular events (OR 0.88, 95% CI 0.77 to 1.00). However, there was evidence for a protective effect of statins for ischaemic stroke (OR 0.78, 95% CI 0.67 to 0.92) but for an increased risk of haemorrhagic stroke (OR 1.72, 95% CI 1.20 to 2.46). There was no evidence that any lipid lowering therapy reduced all-cause mortality or sudden death (OR 1.00, 95% CI 0.83 to 1.20; 3 studies). Three statin trials showed a reduction in subsequent serious vascular events (non-fatal stroke, non-fatal myocardial infarction, vascular death; OR 0.74, 95% CI 0.67 to 0.82).
Comment: The quality of evidence is downgraded by indirectness (data used here from three large studies are sub-group analyses from the trials).