title: Prevalence and risk factors of obstructive sleep apnea among middle-aged urban Indians: a community-based study.
abstract: BACKGROUND
  The epidemiology of obstructive sleep apnea (OSA) and obstructive sleep apnea syndrome (OSAS) is not well studied among Indians. We sought to determine the prevalence and risk factors of OSA in a middle-aged urban Indian population.
  
  
  METHODS
  We conducted a two-stage, cross-sectional, community-based study in four different socioeconomic zones of the South Delhi district, India, from April 2005 to June 2007. In stage 1, subjects of either gender aged 30-65 yrs were administered a questionnaire by door-to-door survey using systematic random sampling. Subjects that responded were classified as habitual and non-habitual snorers. In stage 2, all the habitual and 10% of randomly selected non-habitual snorers were invited for overnight polysomnographic study.
  
  
  RESULTS
  Of the 2860 subjects approached, 2505 (88%) completed stage 1. Habitual snoring was present in 452 (18%) subjects. In stage 2, OSA defined as apnea-hypopnea index 5 was observed in 94 (32.4%) of 290 habitual snorers and 3 (4%) of 75 non-habitual snorers. Estimated population prevalence of OSA and OSAS was 9.3% (95% CI 8.2-10.5%) and 2.8% (2.1-3.4%) respectively. On multivariable analysis, male gender (adjusted odds ratio 3.8 [1.7-4.9]), body-mass index 25 kg/m(2) (4.1 [2.0-8.3]), and abdominal obesity (2.2 [1.9-5.3]) were independently associated with the presence of OSA. A linear trend was observed in the prevalence of OSA across the socioeconomic strata.
  
  
  CONCLUSIONS
  OSA is a significant public health problem in the middle-aged Indian population across the socioeconomic spectrum. OSA is associated with some of the well known risk factors for cardiovascular disease.
authors.affiliation: Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India.
authors.forename: Emmadi V
authors.initials: EV
authors.lastname: Reddy
authors.forename: Tamilarasu
authors.initials: T
authors.lastname: Kadhiravan
authors.forename: Hemant K
authors.initials: HK
authors.lastname: Mishra
authors.forename: Vishnubhatla
authors.initials: V
authors.lastname: Sreenivas
authors.forename: Kumud K
authors.initials: KK
authors.lastname: Handa
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Sinha
authors.forename: Surendra K
authors.initials: SK
authors.lastname: Sharma
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007194:India / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology; D017286:Polysomnography; D015995:Prevalence; D012111:Residence Characteristics; D012307:Risk Factors; D017678:Sex Distribution; D020181:Sleep Apnea, Obstructive / Q000453:epidemiology*; D014505:Urban Population / Q000706:statistics & numerical data*