title: The effect of weight loss on OSA severity and position dependence in the bariatric population.
abstract: BACKGROUND
  The aims of this study were to determine the prevalence of positional obstructive sleep apnea (POSA) in patients undergoing bariatric surgery and to evaluate the effect of weight loss brought about by bariatric surgery on POSA. Furthermore, the authors investigated whether body mass index (BMI), neck circumference, apnea-hypopnea index (AHI), and age are predictors for POSA.
  
  
  METHODS
  A retrospective cohort study was conducted with data collected from patients who were screened for OSA pre-bariatric surgery and completed a follow-up polysomnography post bariatric surgery from August 2008 to November 2012. Descriptive statistics were used to characterize the prevalence of POSA patients, and the Mann-Whitney and Wilcoxon signed-rank tests were used to examine differences between the POSA and non-POSA groups. A logistic regression model was used to determine predictors for POSA.
  
  
  RESULTS
  Thirty-four percent of patients had POSA, which is significantly lower (p<0.001) than in the general population. BMI, neck circumference, and AHI were significantly lower in POSA patients. AHI was the only significant independent predictor for POSA. Of the 91 patients analyzed following bariatric surgery, 35.2% (n=32) no longer had OSA.
  
  
  CONCLUSIONS
  The prevalence of POSA in patients undergoing bariatric surgery is significantly lower than the prevalence noted in the general population. A low AHI was shown to be the only significant independent predictor for the presence of POSA.
authors.affiliation: Department of Otolaryngology, Sint Lucas Andreas Hospital, Jan Tooropstraat 164, 1006 AE, Amsterdam, The Netherlands, sharon.morong@gmail.com.
authors.forename: S
authors.initials: S
authors.lastname: Morong
authors.forename: L B L
authors.initials: LB
authors.lastname: Benoist
authors.forename: M J L
authors.initials: MJ
authors.lastname: Ravesloot
authors.forename: D M
authors.initials: DM
authors.lastname: Laman
authors.forename: N
authors.initials: N
authors.lastname: de Vries
mesh_terms: D000328:Adult; D050110:Bariatric Surgery; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000503:physiopathology* / Q000628:therapy*; D017286:Polysomnography; D012189:Retrospective Studies; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology* / Q000628:therapy*; D016683:Supine Position / Q000502:physiology*; D015431:Weight Loss / Q000502:physiology*