title: The prevalence and patient characteristics of chronic obstructive pulmonary disease in non-smokers in Vietnam and Indonesia: An observational survey.
abstract: OBJECTIVE
  An estimated 25-40% of patients with chronic obstructive pulmonary disease (COPD) have never smoked. We investigated the prevalence and patient characteristics of COPD in non-smokers from Vietnam and Indonesia.
  
  
  METHODS
  This population-based cross-sectional survey of participants from urban and rural Vietnam and Indonesia used a stratified multistage cluster sampling design, with sample and population weights applied to ensure representativeness. Participants were female or male (recruited in the ratio 2:1) non-smokers, 40 years or older and able to perform a spirometry test. Spirometry was performed at a single study visit. Other clinical information was collected via standardized questionnaires.
  
  
  RESULTS
  The 1506 evaluable participants were approximately equally distributed between Vietnam and Indonesia, and rural and urban areas. Overall prevalence of COPD was found to be 6.9% (95% confidence interval (CI): 5.7-8.3), with almost three times higher prevalence in men than women (12.9% (95% CI: 9.1-18.0) vs 4.4% (95% CI: 3.0-6.5)). We found higher rates of COPD in Vietnam than Indonesia (8.1% (95% CI: 5.8-11.3) vs 6.3% (95% CI: 4.8-8.3)), with a particularly high prevalence in urban Vietnam (11.1% (95% CI: 8.1-15.1)). Very few participants (6%) diagnosed to have COPD during the study had been previously diagnosed with COPD. Respiratory symptoms and lower health-related quality of life were more common in participants with COPD.
  
  
  CONCLUSIONS
  The prevalence of COPD in non-smoking individuals from rural and urban Vietnam and Indonesia was 6.9%, of which a significant proportion (94%) were previously undiagnosed.
authors.affiliation: National Tuberculosis Control Program, National Lung Hospital, Hanoi, Vietnam.
authors.forename: Nhung
authors.initials: N
authors.lastname: Nguyen Viet
authors.forename: Faisal
authors.initials: F
authors.lastname: Yunus
authors.forename: Anh
authors.initials: A
authors.lastname: Nguyen Thi Phuong
authors.forename: Van
authors.initials: V
authors.lastname: Dao Bich
authors.forename: Triya
authors.initials: T
authors.lastname: Damayanti
authors.forename: Wiwien Heru
authors.initials: WH
authors.lastname: Wiyono
authors.forename: Laurent
authors.initials: L
authors.lastname: Billot
authors.forename: Rupert W
authors.initials: RW
authors.lastname: Jakes
authors.forename: Namhee
authors.initials: N
authors.lastname: Kwon
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D003430:Cross-Sectional Studies; D004522:Educational Status; D005260:Female; D006801:Humans; D007214:Indonesia / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology* / Q000503:physiopathology; D011788:Quality of Life; D012307:Risk Factors; D012424:Rural Population / Q000706:statistics & numerical data; D017678:Sex Distribution; D013147:Spirometry; D011795:Surveys and Questionnaires; D014505:Urban Population / Q000706:statistics & numerical data; D014744:Vietnam / Q000453:epidemiology
keywords: biomass; chronic obstructive pulmonary disease; indoor air pollution; non-smoking; prevalence