The Relationship Between Excessive Daytime Sleepiness And Metabolic Syndrome In Severe Obstructive Sleep Apnea Hypopnea Syndrome

Background: Excessive daytime sleepiness(EDS), which is commonly considered a cardinal sign of obstructive sleep apnea hypopnea syndrome(OSAHS), may lead to an increased rate of metabolic syndrome(Met S) and be an independent risk factor for cardiovascular morbidity and mortality. The aim of this cross-sectional study was to examine the role of EDS in Met S and its components by researching severe OSA patients.Methods: Consecutive patients who underwent standard polysomnography and diagnosed severe OSA from January 2011 to January 2014 were included. Subjective daytime sleepiness was assessed by using the Epworth sleepiness scale(ESS). Fasting glucose, lipids, insulin and polysomnography parameters were measured. A metabolic score was counted as the total number of the positive diagnostic criteria of Met S for each subject, which indicated the level of metabolic disorder. EDS, which was quantified by the ESS score, was considered when ESS score was ≥10.Results: The prevalence of central obesity, hypertriglyceridemia, low high density lipoprotein-cholesterol, and Met S(78.2% vs. 28.6%) were significantly higher among EDS group compared with control group. Compared with non-EDS patients, patients with EDS showed significantly higher metabolic score(3.22±0.94 vs. 1.96±1.06). Spearman’s rank correlation shown that there were significant correlations between ESS score and components of Met S, including SBP, waist circumference, log TG, HDL-C, log fasting glucose(r=0.165, 0.260, 0.615,-0.275 and 0.277; p=0.029, 0.001, 0.000, 0.000 and 0.000, respectively).Spearman’s correlation also revealed a significant association between the ESS score and metabolic score(r=0.601, p=0.000).Additionally, lowest O2 saturation(La SO2) and mean nocturnal oxygen saturation(Sp O2) during sleep showed significant correlations with ESS score in a negative way(r=-0.263 and-0.347; both p=0.000). After adjustment for confounders, ESS score, Log insulin and age significantly predicted the metabolic score(β=0.567, p=0.000; β=0.197, p=0.001 and β=0.118, p=0.048, respectively).Conclusion: EDS is independently correlated with sum of metabolic components in severe OSA patients. Our study suggested that EDS might be a potentially usefulclinical marker to identify patients with severe OSA at risk of Met S.