title: Obstructive sleep apnea syndrome in the Sao Paulo Epidemiologic Sleep Study.
abstract: OBJECTIVE
  To estimate the prevalence of Obstructive Sleep Apnea Syndrome (OSAS), using current clinical and epidemiological techniques, among the adult population of Sao Paulo, Brazil.
  
  
  METHODS
  This population-based survey used a probabilistic three-stage cluster sample of Sao Paulo inhabitants to represent the population according to gender, age (20-80 years), and socio-economic status. Face-to-face interviews and in-lab full-night polysomnographies using a nasal cannula were performed. The prevalence of OSAS was determined according to the criteria of the most recent International Classification of Sleep Disorders (ICDS-2) from American Academy of Sleep Medicine (2005).
  
  
  RESULTS
  A total of 1042 volunteers underwent polysomnography (refusal rate=5.4%). The mean age+/-SD was 42+/-14 years; 55% were women and 60% had a body mass index>25 kg/m(2). OSAS was observed in 32.8% of the participants (95% CI, 29.6-36.3). A multivariate logistic regression model identified several independent and strong associations for the presence of OSAS: men had greater association than women (OR=4.1; 95% CI, 2.9-5.8; P<0.001) and obese individuals (OR=10.5; 95% CI, 7.1-15.7; P<0.001) than individuals of normal weight. The adjusted association factor increased with age, reaching OR=34.5 (95% CI, 18.5-64.2; P<0.001) for 60-80 year olds when compared to the 20-29 year old group. Low socio-economic status was a protective factor for men (OR=0.4), but was an associated factor for women (OR=2.4). Self-reported menopause explained this increased association (age adjusted OR=2.1; 95% CI, 1.4-3.9; P<0.001), and it was more frequent in the lowest class (43.1%) than either middle class (26.1%) or upper class (27.8%) women.
  
  
  CONCLUSIONS
  This study is the first apnea survey of a large metropolitan area in South America identifying a higher prevalence of OSAS than found in other epidemiological studies. This can be explained by the use of the probabilistic sampling process achieving a very low polysomnography refusal rate, the use of current techniques and clinical criteria, inclusion of older groups, and the higher prevalence of obesity in the studied population.
authors.affiliation: Disciplina de Medicina e Biologia do Sono, Departamento de Psicobiologia, Universidade Federal de Sao Paulo - UNIFESP, Sao Paulo, Brazil.
authors.forename: Sergio
authors.initials: S
authors.lastname: Tufik
authors.forename: Rogerio
authors.initials: R
authors.lastname: Santos-Silva
authors.forename: Jose Augusto
authors.initials: JA
authors.lastname: Taddei
authors.forename: Lia Rita Azeredo
authors.initials: LR
authors.lastname: Bittencourt
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D001938:Brazil / Q000453:epidemiology; D005260:Female; D006306:Health Surveys; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009765:Obesity / Q000453:epidemiology*; D050177:Overweight / Q000453:epidemiology; D017286:Polysomnography; D015995:Prevalence; D017678:Sex Distribution; D020181:Sleep Apnea, Obstructive / Q000453:epidemiology*; D014505:Urban Population / Q000706:statistics & numerical data*; D055815:Young Adult