Twenty-seven RCTs (n=97,981) were included. Twenty-six of these RCTs were included in the meta-analyses as one RCT (n=3,853) was unsuccessfully randomised.
Statins significantly reduced stroke incidence compared with the control; the OR was 0.79 (95% CI: 0.73, 0.85). No statistically significant heterogeneity was found (P=0.35). The results were similar after excluding studies in which stroke was not a pre-specified outcome, and after including one RCT with unsuccessful randomisation.
Statins reduced fatal strokes by 9% compared with the control, but the reduction was not statistically significant; the OR (15 RCTs) was 0.91 (95% CI: 0.76, 1.10). No statistically significant heterogeneity was found (P=0.71).
There was no statistically significant difference in haemorrhagic stroke between statins and control; the OR (8 RCTs) was 0.90 (95% CI: 0.65, 1.22). No statistically significant heterogeneity was found (P=0.15). The results were similar after including one RCT with unsuccessful randomisation.
The reduction in LDL-C ranged from about 11 to 52% among studies. There was a significant correlation (r) between LDL-C reduction and stroke (r=0.58, P=0.002) and between LDL-C reduction and IMT (r=0.65, P=0.004).
Each 10% reduction in LDL-C reduced the risk of any type of stroke by 15.6% (95% CI: 6.7, 23.6) and reduced carotid IMT by 0.73% (95% CI: 0.27, 1.19).
The asymmetry of the funnel plot and results from Egger's analysis (P=0.056) suggested the presence of publication bias.