title: High hypopnea/apnea ratio (HAR) in extreme obesity.
abstract: OBJECTIVE
  The study was performed to evaluate the hypothesis that the extremely obese manifest sleep disordered breathing with a preponderance of hypopneas and relative paucity of obstructive apneas.
  
  
  METHODS
  Retrospective review of 90 adults with obstructive sleep apnea-hypopnea syndrome (OSAHS) matched for age and gender, comparing two groups, Group A: body mass index (BMI) < 35, Group B: BMI ≥ 45.
  
  
  METHODS
  age < 18 years, pregnancy, ≥ 5 central apneas/hour, BMI ≥ 35 < 45.
  
  
  METHODS
  Hypopnea/apnea ratio (HAR); secondary measures: obstructive apnea-hypopnea index (AHI), obstructive and central apnea indices, hypopnea index (HI), oxygen saturation (SpO2) nadir, end-tidal carbon dioxide tension (PetCO2), and presence of obesity-hypoventilation syndrome (OHS).
  
  
  METHODS
  t-test for independent samples; Mann-Whitney, linear regression with natural log transformation, and Kruskal-Wallis χ(2). Descriptive statistics were expressed as interquartile range, median and mean ± standard deviation, p < 0.05 considered significant.
  
  
  RESULTS
  Group A (n = 45): age = 50.6 ± 11.5 years, BMI = 28.9 ± 4 kg/m(2); Group B (n = 45): age = 47.4 ± 12.7 years, BMI = 54.5 ± 8 kg/m(2). HAR was significantly higher in Group B (38.8 ± 50.7) than Group A (10.6 ± 16.5), p = 0.0006, as was HI (28.7 ± 28.6 in B vs 12.6 ± 8.4 in A, p = 0.0005) and AHI (35.5 ± 33.8 vs 22 ± 23, p = 0.03), but not apnea index. HAR was significantly higher in Group B regardless of race, gender, or presence of OHS. The BMI was the only significant predictor of HAR (adjusted r(2) = 0.138; p = 0.002) in a linear regression model with natural log transformation of the HAR performed for age, gender, race, BMI, and PetCO2.
  
  
  CONCLUSIONS
  Extremely obese patients manifest OSAHS with a preponderance of hypopneas.
authors.affiliation: University of Texas Health Science Center at Houston, Houston, TX ; Memorial Hermann Hospital-Texas Medical Center Sleep Disorders Center, Houston, TX.
authors.forename: Reeba
authors.initials: R
authors.lastname: Mathew
authors.affiliation: University of Texas Health Science Center at Houston, Houston, TX ; Memorial Hermann Hospital-Texas Medical Center Sleep Disorders Center, Houston, TX.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Castriotta
mesh_terms: D015992:Body Mass Index; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000150:complications* / Q000503:physiopathology; D017286:Polysomnography; D012189:Retrospective Studies; D012891:Sleep Apnea Syndromes / Q000209:etiology / Q000503:physiopathology; D020181:Sleep Apnea, Obstructive / Q000209:etiology* / Q000503:physiopathology; D018709:Statistics, Nonparametric
keywords: Obesity; gender differences; hypopnea; hypopnea/apnea ratio.; obesity-hypoventilation syndrome; obstructive sleep apnea; sleep-disordered breathing
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