title: The impact of obstructive sleep apnea on nonalcoholic fatty liver disease in patients with severe obesity.
abstract: OBJECTIVE
  Obstructive sleep apnea (OSA) is common among candidates for bariatric surgery. OSA and its associated intermittent hypoxia have been implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis. A large cohort of bariatric surgery patients was studied in an effort to explore the relationship between OSA severity, hypoxia, metabolic syndrome, and the severity of NAFLD.
  
  
  METHODS
  Bariatric surgery candidates who underwent both polysomnography and liver biopsy were studied. The severity of OSA as determined by the apnea-hypopnea index (AHI) and parameters of hypoxia was studied in relation to extent of abnormalities of liver histology as measured by the presence of hepatic steatosis, inflammation, and fibrosis.
  
  
  RESULTS
  The study cohort included 362 patients with a mean age of 46.2 years and BMI of 49.9 kg/m(2) . On the basis of AHI, 26% of the cohort had no OSA, 32% mild OSA, 22% moderate OSA, and 20% severe OSA. For the study subjects without metabolic syndrome, positive correlations were found between OSA severity, as measured by AHI, and parameters of hypoxia, with the severity of NAFLD.
  
  
  CONCLUSIONS
  OSA severity and its accompanying hypoxia are associated with the severity of NAFLD.
authors.affiliation: Geisinger Obesity Institute, Danville, Pennsylvania, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Benotti
authors.affiliation: Geisinger Obesity Institute, Danville, Pennsylvania, USA.
authors.forename: G Craig
authors.initials: GC
authors.lastname: Wood
authors.affiliation: Geisinger Obesity Institute, Danville, Pennsylvania, USA.
authors.forename: George
authors.initials: G
authors.lastname: Argyropoulos
authors.affiliation: University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Allan
authors.initials: A
authors.lastname: Pack
authors.affiliation: University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Brendan T
authors.initials: BT
authors.lastname: Keenan
authors.affiliation: Pennsylvania State University, University Park, Pennsylvania, USA.
authors.forename: Xiang
authors.initials: X
authors.lastname: Gao
authors.affiliation: Temple University, Philadelphia, Pennsylvania, USA.
authors.forename: Glenn
authors.initials: G
authors.lastname: Gerhard
authors.affiliation: Geisinger Obesity Institute, Danville, Pennsylvania, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Still
mesh_terms: D000328:Adult; D050110:Bariatric Surgery; D015331:Cohort Studies; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000209:etiology / Q000503:physiopathology*; D007249:Inflammation; D008099:Liver / Q000473:pathology; D008297:Male; D008875:Middle Aged; D065626:Non-alcoholic Fatty Liver Disease / Q000150:complications*; D009767:Obesity, Morbid / Q000150:complications* / Q000601:surgery; D017286:Polysomnography; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000150:complications*