Effects of CPAP on Metabolic Syndrome in Patients With OSA

Obstructive sleep apnea (OSA) is associated with metabolic syndrome (MS), but it is unclear whether OSA treatment with continuous positive airway pressure (CPAP) can revert MS. Does OSA treatment with CPAP per se have effects on the MS reversibility and the associated metabolic, adiposity and vascular parameters? The TREATOSA-MS is a randomized placebo-controlled trial that enrolled adult patients with a recent diagnosis of MS, and moderate/severe OSA (apnea-hypopnea index, [AHI] ≥15 events/h) to undergo therapeutic CPAP or nasal strips (placebo group) for 6 months. Before and after each intervention, we measured anthropometric variables, blood pressure, glucose, and lipid profile. To control potential related mechanisms and consequences, we also measured adiposity biomarkers (leptin and adiponectin), body composition, food intake, physical activity, subcutaneous and abdominal fat (visceral and hepatic fat) and endothelial function. One-hundred patients (79% men; age: 48±9 years; body mass index: 33±4 kg/m2; AHI: 58±29 events/h) completed the study (n=50 per group). The mean CPAP adherence was 5.5±1.5 h/night. After 6-months, most patients with OSA randomized to CPAP kept the MS diagnosis but the rate of MS reversibility was higher than observed in the placebo group (18% vs. 4%; OR: 5.27; 95% CI 1.27 to 35.86; p=0.04). In the secondary analysis, CPAP did not promote significant reductions in the individual components of MS, weight, hepatic steatosis, lipid profile, adiponectin and leptin but promoted a very modest reduction in visceral fat and improved endothelial function (all analyses were adjusted for baseline values). Despite the higher rate of MS reversibility after CPAP therapy as compared to placebo, most patients still have this diagnosis. The lack of significant/relevant effects on adiposity biomarkers and depots supports the modest role of OSA in modulating MS.