Ten RCTs were included (845 participants, range 16 to 204). Quality scores ranged from 1 to 5 and most studies scored 2 or 3 out of 5. Six trials were described as being at low risk of bias (scoring ≥3 points) and four trials were judged to be at a high risk of bias. Nine studies were described as being double-blind; one study did not use blinding. Two studies were crossover trials.
Statin therapy significantly improved flow-mediated dilatation compared with placebo (WMD 0.94%, 95% CI 0.38% to 1.5%; Ι²=67%; 10 RCTs). No significant publication bias was detected.
Subgroup analysis showed that patients with a BMI more than 27.6 kg/m² did not benefit from statin therapy (four RCTs). Significant benefit was seen in patients with BMI of 27.6 kg/m² or less (five RCTs); no significant heterogeneity was seen. Further subgroup analysis results were reported.
Meta-regression analyses found that lower BMI, younger age, higher baseline high-density lipoprotein cholesterol and lower baseline systolic and diastolic blood pressure were all significantly associated with improvement in flow-mediated dilatation.