Effect of CPAP on Endothelial Function in Subjects With Obstructive Sleep Apnea: A Meta-Analysis.

Obstructive sleep apnea (OSA) is related to endothelial dysfunction. CPAP is the first-line treatment for OSA. We conducted a meta-analysis to evaluate the effect of CPAP on endothelial function in subjects with OSA. The PubMed, Embase, and Cochrane Library databases were searched. The overall effects were measured by the weighted mean difference with a 95% CI. Subgroup and meta-regression analyses were used to explore the sources of between-study heterogeneity. Eleven studies were eligible for the meta-analysis. A random-effects model revealed that CPAP significantly improved endothelial function as assessed by flow-mediated dilation (weighted mean difference of 2.92, 95% CI 2.21-3.63, P < .001), whereas there was no significant improvement in endothelial function in response to nitroglycerin-mediated dilation (weighted mean difference of 0.90, 95% CI -1.63 to 3.43, P = .48). Age, sex, CPAP compliance and duration, and sleep-related variables had no effect on reduction in arterial stiffness after CPAP. Sensitivity analyses indicated that the protective effect of CPAP on endothelial function was robust. CPAP significantly improved flow-mediated dilation in subjects with OSA. Long-term randomized controlled trials with larger sample sizes are needed to confirm the positive effect of CPAP on endothelial function in subjects with OSA.