Determinants of obstructive sleep apnea syndrome: Pro-inflammatory state and dysfunction of high-density lipoprotein.

Abstract

The goal of this study was to determine variables preceding and predicting incident obstructive sleep apnea syndrome (OSAS) in the population at large. Anthropometric, lipid, and non-lipid variables in participants with newly developing OSAS (n=131) were compared with those of a cohort sample (n=2615) of the Turkish Adult Risk Factor study. Available values preceding (by a median of 32mo) the development of OSAS were used in multivariable Cox regression models. Significant determinants of OSAS assessed by group differences were waist/neck circumference and fibrinogen. Fasting triacylglycerols, systolic blood pressure, and C-reactive protein in men and low sex hormone-binding globulin and elevated homeostatic model assessment in women were further significant covariates. Cox regression analysis for the risk of incident OSAS confirmed the independent predictive value of central obesity measures, especially neck circumference (having a twofold hazard ratio) and younger age. Age-adjusted former smoking status and-compared with the lowest tertile-the upper two tertiles of fibrinogen (relative risk=1.66, 95% confidence interval: 1.05-2.63) were significant predictors. Elevated triacylglycerols in males and high apolipoprotein B and lowest high-density lipoprotein cholesterol tertile in females also predicted subsequent OSAS. Systolic blood pressure and total cholesterol did not prove to be independent predictors in multivariable adjusted Cox models in which partial sex-dependent independence of obesity measures of the previously stated five variables was essentially retained. An enhanced pro-inflammatory state appeared to be the underlying pathophysiologic mechanism for OSAS, whereas in men, the added factor of high-density lipoprotein dysfunction was suggested. Because it contributes to the pro-inflammatory state, discontinuance of smoking was another further significant predictor of OSAS.