title: Snoring in a sitting position and neck circumference are predictors of sleep apnea in Chinese patients.
abstract: BACKGROUND
  Snoring is a common symptom among the adult population, and it is the most common complaint in patients with obstructive sleep apnea (OSA) syndrome. Patients who snore in a sitting position while taking a nap or sleeping may have a narrower upper airway. The aim of this study was to evaluate if snoring in a sitting position is a predictor of OSA in patients.
  
  
  METHODS
  We prospectively enrolled 166 SS+ (with a history of snoring in a sitting position) subjects and 139 SS- (who denied having a history of snoring in a sitting position) patients. All of the participants received questionnaires as well as a standard polysomnography thereafter.
  
  
  RESULTS
  Patients with self-reported snoring in a sitting position (with a tilt position greater than 70°, SS+ group) had a higher body mass index as well as greater neck, waist, and buttock circumference and scored higher on the Epworth Sleepiness Scale. During the polysomnographic study, the SS+ group had a higher percentage of N1 sleep and lower percentage of N2 sleep. In addition, the SS+ group had a higher apnea-hypopnea index (AHI) as well as higher arousal index and oxygen desaturation index. The sensitivity and specificity of the SS+ group for OSA (defined as AHI ≥ 5) were 0.59 and 0.73, respectively, with a positive predictive value of 0.93. The likelihood ratio was 2.2. On the other hand, the sensitivity and specificity of the SS+ group for moderate to severe OSA (defined as AHI ≥ 15) were 0.82 and 0.48, respectively. Both SS+ and greater neck circumference have a high likelihood ratio for diagnosing OSA.
  
  
  CONCLUSIONS
  In the present study, the symptoms of self-reported snoring in a sitting position and greater neck circumference can be useful clinical predictors of OSA in Chinese patients.
authors.affiliation: Division of Chest Medicine, Department of Internal Medicine, Buddhist Tzu Chi General Hospital, No. 707, Section 3, Chung-Yang Rd., Hualien, 970, Taiwan, evan19760202@yahoo.com.tw.
authors.forename: En-Ting
authors.initials: ET
authors.lastname: Chang
authors.forename: Miao-Chun
authors.initials: MC
authors.lastname: Yang
authors.forename: Hsiu-Mei
authors.initials: HM
authors.lastname: Wang
authors.forename: Hui-Ling
authors.initials: HL
authors.lastname: Lai
mesh_terms: D000328:Adult; D000886:Anthropometry; D015992:Body Mass Index; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009333:Neck; D010100:Oxygen / Q000097:blood; D017286:Polysomnography; D011187:Posture; D011446:Prospective Studies; D012307:Risk Factors; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000453:epidemiology; D012894:Sleep Stages; D012913:Snoring / Q000175:diagnosis* / Q000453:epidemiology; D013223:Statistics as Topic; D011795:Surveys and Questionnaires; D013624:Taiwan
chemical_list: D010100:Oxygen