CPAP for the metabolic syndrome in patients with obstructive sleep apnea

Obstructive sleep apnea is associated with an increased prevalence of the metabolic syndrome and its components. It is unclear whether treatment of obstructive sleep apnea syndrome with continuous positive airway pressure (CPAP) would modify these outcomes.

In our double-blind, placebo-controlled trial, we randomly assigned patients with obstructive sleep apnea syndrome to undergo 3 months of therapeutic CPAP followed by 3 months of sham CPAP, or vice versa, with a washout period of 1 month in between. Before and after each intervention, we obtained measurements of anthropometric variables, blood pressure, fasting blood glucose levels, insulin resistance (with the use of homeostasis model assessment), fasting blood lipid profile, glycated hemoglobin levels, carotid intima-media thickness, and visceral fat. The metabolic syndrome was defined according to National Cholesterol Education Program Adult Treatment Panel III criteria, with Asian cutoff values for abdominal obesity.

A total of 86 patients completed the study, 75 (87%) of whom had the metabolic syndrome. CPAP treatment (vs. sham CPAP) was associated with significant mean decreases in systolic blood pressure (3.9 mm Hg; 95% confidence interval [CI], 1.4 to 6.4; P=0.001), diastolic blood pressure (2.5 mm Hg; 95% CI, 0.9 to 4.1; P<0.001), serum total cholesterol (13.3 mg per deciliter; 95% CI, 5.3 to 21.3; P=0.005), non-high-density lipoprotein cholesterol (13.3 mg per deciliter; 95% CI, 4.8 to 21.8; P=0.009), low-density lipoprotein cholesterol (9.6 mg per deciliter; 95% CI, 2.5 to 16.7; P=0.008), triglycerides (18.7 mg per deciliter; 95% CI, 4.3 to 41.6; P=0.02), and glycated hemoglobin (0.2%; 95% CI, 0.1 to 0.4; P=0.003). The frequency of the metabolic syndrome was reduced after CPAP therapy (reversal found in 11 of 86 patients [13%] undergoing CPAP therapy vs. 1 of 86 [1%] undergoing sham CPAP). Accelerated hypertension developed 1 patient receiving CPAP therapy first, intolerance to CPAP developed in 2 others, and another patient declined to continue sham CPAP.

In patients with moderate-to-severe obstructive sleep apnea syndrome, 3 months of CPAP therapy lowers blood pressure and partially reverses metabolic abnormalities. (Funded by Pfizer; ClinicalTrials.gov number, NCT00694616.).