title: Visceral Obesity Mediates the Association Between Metabolic Syndrome and Obstructive Sleep Apnea Syndrome.
abstract: BACKGROUND
  Metabolic syndrome (MetS) and visceral obesity are more prevalent in obstructive sleep apnea syndrome (OSAS). We investigated the association of visceral fat (VF) measures with the components of MetS in OSAS patients with different severity levels, according to World Health Organization (WHO, 1999), National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III, 2001), and International Diabetes Federation (IDF, 2005) definitions.
  
  
  METHODS
  Study population was grouped according to polysomnography results as non-OSAS [who had apnea-hypopnea index (AHI) <5, n = 51], mild OSAS (5 < AHI <15, n = 52), moderate OSAS (15 < AHI <30, n = 53), and severe OSAS (AHI >30, n = 53). VF ratio was measured by abdominal bioimpedance analysis. Waist-to-hip ratio (WHR), homeostasis model assessment of insulin resistance (HOMA-IR), and lipid profiles were assessed in all subjects.
  
  
  RESULTS
  The prevelance of MetS in OSAS patients was 30.0%, 35.6%, and 44.4% according to WHO, NCEP-ATP III, and IDF definitions, respectively. MetS was found in 27.5% non-OSAS and 72.8% OSAS according to at least one definition (P = 0.012). Within OSAS group, 27.2% subjects had average, 38.0% had slightly excessive, and 34.8% had an excessive VF ratio. The prevelance of MetS was similar in various VF ratios (P > 0.05). However HOMA-IR increased progressively with VF ratio after adjusting for age, gender, and body mass index (BMI; P = 0.02). AHI increased progressively with BMI (P = 0.02), WHR (P = 0.03), VF ratio (P = 0.01), HOMA-IR (P = 0.02), and MetS (P = 0.016).
  
  
  CONCLUSIONS
  Since severity of OSAS, in terms of AHI and insulin resistance, is both associated with VF rather than BMI, VF should be suggested to link OSAS and MetS. The IDF definition is more sensitive in OSAS patients to diagnose MetS, as central obesity and insulin resistance are obligatory components. This would allow clinicians to intervent earlier to adverse metabolic outcomes of OSAS.
authors.affiliation: 1 Department of Endocrinology and Metabolism, Ankara Diskapi Yildirim Beyazit Teaching and Research Hospital , Ankara, Turkey .
authors.forename: Nujen Colak
authors.initials: NC
authors.lastname: Bozkurt
authors.affiliation: 1 Department of Endocrinology and Metabolism, Ankara Diskapi Yildirim Beyazit Teaching and Research Hospital , Ankara, Turkey .
authors.forename: Selvihan
authors.initials: S
authors.lastname: Beysel
authors.affiliation: 1 Department of Endocrinology and Metabolism, Ankara Diskapi Yildirim Beyazit Teaching and Research Hospital , Ankara, Turkey .
authors.forename: Basak
authors.initials: B
authors.lastname: Karbek
authors.affiliation: 1 Department of Endocrinology and Metabolism, Ankara Diskapi Yildirim Beyazit Teaching and Research Hospital , Ankara, Turkey .
authors.forename: İlknur Ozturk
authors.initials: İO
authors.lastname: Unsal
authors.affiliation: 1 Department of Endocrinology and Metabolism, Ankara Diskapi Yildirim Beyazit Teaching and Research Hospital , Ankara, Turkey .
authors.forename: Evrim
authors.initials: E
authors.lastname: Cakir
authors.affiliation: 2 Department of Internal Medicine, School of Medicine (Kastamonu), Hacettepe University , Ankara, Turkey .
authors.forename: Tuncay
authors.initials: T
authors.lastname: Delibasi
mesh_terms: D050154:Adiposity; D000328:Adult; D015992:Body Mass Index; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D050152:Intra-Abdominal Fat; D008297:Male; D024821:Metabolic Syndrome / Q000150:complications*; D008875:Middle Aged; D056128:Obesity, Abdominal / Q000150:complications*; D017286:Polysomnography; D015995:Prevalence; D020181:Sleep Apnea, Obstructive / Q000150:complications*; D016896:Treatment Outcome; D049629:Waist-Hip Ratio