title: Combined effects of sleep disordered breathing and metabolic syndrome on endothelial function: the Wisconsin Sleep Cohort study.
abstract: OBJECTIVE
  To examine the combined impact of sleep disordered breathing (SDB) and metabolic syndrome (MetS) in endothelial dysfunction.
  
  
  METHODS
  Cross-sectional assessment of endothelial function, MetS and SDB status in a population-based sample.
  
  
  METHODS
  Community-based cohort.
  
  
  METHODS
  Participants (n = 431) from the Wisconsin Sleep Cohort were studied between 2004 and 2007. MetS was defined following the National Cholesterol Education Program criteria. SDB severity was defined by the apnea-hypopnea index ([AHI] events/h of sleep) during overnight polysomnography. Fasting lipids, glucose, and insulin were measured and homeostasis model assessment was calculated to quantify insulin resistance (HOMA-IR). Multivariable linear regression was used to assess associations of brachial artery flow-mediated dilation (FMD) with SDB, MetS, and their interaction.
  
  
  METHODS
  None.
  
  
  RESULTS
  Participants averaged 60.2 years of age (SD 7.8 years), 44% were female, and 97% Caucasian. MetS was present in 35%; 22% had AHI ≥ 15 events/hour. Of the no-MetS group, 7% had AHI ≥ 15 events/hour. FMD (mean 5.5%; SD 3.5%) was inversely associated with age (r = -0.16, P = 0.001) and mean brachial artery diameter (r = -0.29, P < 0.001). Multivariate linear models adjusted for CVD risk factors showed that the negative association between SDB and FMD was present among subjects with MetS (β FMD(per unit log2(AHI+1)) = -0.55%, P = 0.014), but not among subjects with normal metabolic function (β = 0.13, not significant), P for interaction = 0.011.
  
  
  CONCLUSIONS
  Sleep disordered breathing and concurrent metabolic syndrome are synergistically associated with worse endothelial function. Individuals with both of these conditions appear to be at a significantly higher risk for cardiovascular disease complications.
authors.affiliation: University of Wisconsin School of Medicine and Public Health, Madison, WI.
authors.forename: Claudia E
authors.initials: CE
authors.lastname: Korcarz
authors.affiliation: University of Wisconsin School of Medicine and Public Health, Madison, WI.
authors.forename: James H
authors.initials: JH
authors.lastname: Stein
authors.affiliation: University of Wisconsin School of Medicine and Public Health, Madison, WI.
authors.forename: Paul E
authors.initials: PE
authors.lastname: Peppard
authors.affiliation: University of Wisconsin School of Medicine and Public Health, Madison, WI.
authors.forename: Terry B
authors.initials: TB
authors.lastname: Young
authors.affiliation: University of Wisconsin School of Medicine and Public Health, Madison, WI.
authors.forename: Jodi H
authors.initials: JH
authors.lastname: Barnet
authors.affiliation: University of Wisconsin School of Medicine and Public Health, Madison, WI.
authors.forename: F Javier
authors.initials: FJ
authors.lastname: Nieto
mesh_terms: D001916:Brachial Artery / Q000503:physiopathology; D002318:Cardiovascular Diseases / Q000150:complications / Q000503:physiopathology; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004198:Disease Susceptibility; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D024821:Metabolic Syndrome / Q000150:complications* / Q000503:physiopathology*; D008875:Middle Aged; D017286:Polysomnography; D012307:Risk Factors; D012891:Sleep Apnea Syndromes / Q000150:complications* / Q000503:physiopathology*; D014922:Wisconsin
keywords: cardiovascular disease; endothelial function; metabolic syndrome; obesity; sleep apnea