Beneficial effect of continuous positive airway pressure on lipid profiles in obstructive sleep apnea: a meta-analysis

Dyslipidemia is considered as one mechanism causing cardiovascular sequelae in obstructive sleep apnea (OSA). Continuous positive airway pressure (CPAP) can reduce cardiovascular morbidities but its effect on lipid profiles is inconclusive. This study aimed to investigate the effects of CPAP on lipid profiles by a meta-analysis of the existing randomized controlled trials. Studies were retrieved from MEDLINE/PubMed, EMBASE, CENTRAL, commercial websites, and article references up to August 2013 following the protocols (PROSPERO CRD42012002636). Randomized controlled trials investigating the CPAP effects on changes in lipid profiles in adult patients with OSA were included. Two independent researchers extracted relevant data in duplicate. The pooled effect was analyzed by fixed-effect generic inverse variance, and the heterogeneity was assessed using the I (2) statistic. Six trials with 348 patients and 351 controls were included. CPAP significantly lowered total cholesterol (mean, -6.23 mg/dl; 95% CI, -8.73 to -3.73; I (2), 0 %; p < 0.001), triglyceride (mean, -12.60 mg/dl; 95% CI, -18.80 to -6.41; I (2), 25 %; p < 0.001), and high-density lipoprotein (mean, -1.05 mg/dl; 95% CI, -1.69 to -0.40; I (2), 0 %; p = 0.001), but not low-density lipoprotein (mean, -1.01 mg/dl; 95% CI, -5.04 to 3.02; I (2), 0 %; p = 0.62). The lipid-lowering effects were homogeneous across the studies. By subgroup analysis, the reductions of lipid profiles were associated with the cross-over design, subtherapeutic CPAP as placebo, enrolled patients with moderate-to-severe OSA or daytime sleepiness, and CPAP treatment with short-term duration or good compliance. This meta-analysis validates the observation that CPAP can reduce lipid profiles in patients with OSA.