title: Obesity plays an independent worsening modifying effect on nocturnal hypoxia in obstructive sleep apnea.
abstract: OBJECTIVE
  Obesity's association with obstructive sleep apnea syndrome (OSAS) is well established. The aim of this study was to examine the impact of obesity on nocturnal hypoxia.
  
  
  METHODS
  Twenty two thousand seven hundred and ninety three patients aged 21-80 years who underwent whole night polysomnography during 2000-2009 were included in the study. For each patient, percent sleep time spent with oxyhemoglobin desaturation lower than 90% was calculated (%NODP). Nocturnal hypoxia was analyzed by gender, age, OSAS severity, and body mass index (BMI) categories.
  
  
  RESULTS
  Nocturnal hypoxia was positively correlated with BMI, OSAS severity, and age, but not with gender. The differences in %NODP between the two obese groups and non-obese varied from 0.55% to more than a 20% increase and were correlated with age and OSAS severity. The %NODP ratio between the two obese groups and the non-obese was independent of age and OSAS severity. There was a nearly twofold increase in %NODP in obese patients and a threefold increase in the morbidly obese relative to the non-obese.
  
  
  CONCLUSIONS
  Our results indicate that obesity plays an independent worsening modifying effect on nocturnal hypoxia in OSAS.
authors.affiliation: Lloyd Rigler Sleep Apnea Laboratory, Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel. igabbay@gmail.com
authors.forename: Itay E
authors.initials: IE
authors.lastname: Gabbay
authors.forename: Uri
authors.initials: U
authors.lastname: Gabbay
authors.forename: Peretz
authors.initials: P
authors.lastname: Lavie
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D015992:Body Mass Index; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000503:physiopathology; D017286:Polysomnography; D012189:Retrospective Studies; D012720:Severity of Illness Index; D012737:Sex Factors; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000503:physiopathology; D055815:Young Adult