title: Body Fat Distribution Ratios and Obstructive Sleep Apnea Severity in Youth With Obesity.
abstract: OBJECTIVE
  Obesity and regional fat distribution, measured by neck fat mass percentage using dual-energy X-ray absorptiometry (DXA), correlate with obstructive sleep apnea (OSA) severity in adults. In obese children, neck-to-waist-circumference ratio predicts OSA. This study examined associations between body fat percentage and distribution and sleep-disordered breathing (SDB) severity in obese youth, measured with DXA.
  
  
  METHODS
  Cross-sectional retrospective study conducted at a tertiary children's hospital. Participants were aged 6 to 18 years with obesity (body mass index [BMI] > 99th percentile [BMI z-score 2.35] or > 95th percentile with comorbidity). They underwent polysomnography and DXA to quantify body fat percentage and distribution ratios (neck-to-abdominal fat percentage [NAF % ratio]). SDB was defined as apnea-hypopnea index (AHI) > 5 and OSA as obstructive AHI (OAHI) > 1 event/h. Relationships of BMI z-score and NAF % ratio to log AHI and log OAHI were evaluated.
  
  
  RESULTS
  Thirty individuals participated; 18 male; median age 14.1 years. Twenty-four individuals had BMI z-scores > 2.35. Ten had AHI > 5 events/h. NAF % ratio was significantly associated with log AHI in males and with log OAHI in all, whereas total fat mass percent was not. The association between log OAHI and NAF % ratio was significant in males, but not females. NAF % ratio was significantly associated with log OAHI in those with BMI z-score above 2.35.
  
  
  CONCLUSIONS
  NAF % ratio was associated with OSA severity in males and youth with BMI > 99th percentile; however, total fat mass percentage was not, suggesting that body fat distribution is associated with OSA risk in youth.
authors.affiliation: The Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Amy
authors.initials: A
authors.lastname: Glicksman
authors.affiliation: Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.|University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Stasia
authors.initials: S
authors.lastname: Hadjiyannakis
authors.affiliation: University of Ottawa, Ottawa, Ontario, Canada.|Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Barrowman
authors.affiliation: Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.
authors.forename: Scott
authors.initials: S
authors.lastname: Walker
authors.affiliation: Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada.
authors.forename: Lynda
authors.initials: L
authors.lastname: Hoey
authors.affiliation: Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.|University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Sherri Lynne
authors.initials: SL
authors.lastname: Katz
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D050218:Body Fat Distribution / Q000379:methods / Q000706:statistics & numerical data*; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D063766:Pediatric Obesity / Q000150:complications*; D017286:Polysomnography; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000150:complications*
keywords: DXA; obesity; obstructive sleep apnea; ratio; youth