Association between continuous positive airway pressure and circulating omentin levels in patients with obstructive sleep apnoea

Inflammation and oxidative stress play important roles in the pathogenesis of obstructive sleep apnoea syndrome (OSAS). Omentin is expressed in visceral adipose tissue and is associated with the inflammatory response. The aim of this study was to assess the relationship between OSAS and omentin based on a comparison of its serum levels at baseline and after 3 months of continuous positive airway pressure (CPAP) therapy. Ninety-six newly diagnosed OSAS patients and 31 non-apnoeic controls were enrolled in this study. Blood samples were obtained in the morning after polysomnography. Within the OSAS group, 30 patients were started on CPAP therapy and then reassessed clinically, including a blood test for serum omentin and other biochemical analysis, at 3 months. Serum omentin levels were significantly lower in the OSAS group than in the control group (27.7 +/- 7.6 and 42.5 +/- 5.2 ng/mL, P < 0.001). In the subgroup analysis, omentin concentrations were significantly lower in patients with severe OSAS than in those with mild/moderate OSAS (P < 0.001). Circulating omentin levels were significantly correlated with the apnoea-hypopnoea index (AHI), mean SaO(2), oxygen desaturation index, and serum C-reactive protein levels. Treatment with CPAP resulted in a significant increase in circulating omentin levels after 3 months, from 22.7 +/- 1.4 to 41.2 +/- 3.3 ng/mL (P < 0.001). OSAS is associated with low serum omentin levels, and these levels can be reversed by effective CPAP treatment.