title: Estimating the prevalence of COPD in Canada: Reported diagnosis versus measured airflow obstruction.
abstract: BACKGROUND
  Estimates of chronic obstructive pulmonary disease (COPD) prevalence based on self-reports of a diagnosis are thought to underestimate the prevalence of COPD in Canada.
  
  
  METHODS
  Pre-bronchodilator spirometry measures were obtained from the 2007 to 2009 Canadian Health Measures Survey for 2,487 individuals aged 35 to 79. The prevalence of self-reported chronic bronchitis symptoms and self-reported diagnosis of COPD by a health care professional was compared with the prevalence of measured airflow obstruction according to seven definitions, including the Global Initiative for Obstructive Lung Disease (GOLD) criteria.
  
  
  RESULTS
  The prevalence of measured airflow obstruction compatible with COPD was two to six times greater than estimates based on self-reports of a diagnosis. An estimated 16.6% (95% CI: 14.3%-18.9%) of people aged 35 to 79 had pre-bronchodilator airflow obstruction as defined by ≥ GOLD stage I, and 8.1% (95% CI: 6.0%-10.2%) had ≥ GOLD stage II.
  
  
  CONCLUSIONS
  This study suggests that the prevalence of COPD in Canada has been underestimated.
authors.affiliation: formerly with the Public Health Agency of Canada, Ottawa, Ontario.
authors.forename: Jessica
authors.initials: J
authors.lastname: Evans
authors.affiliation: University of Ottawa.
authors.forename: Yue
authors.initials: Y
authors.lastname: Chen
authors.affiliation: University of British Columbia.
authors.forename: Pat G
authors.initials: PG
authors.lastname: Camp
authors.affiliation: Dalhousie University.
authors.forename: Dennis M
authors.initials: DM
authors.lastname: Bowie
authors.affiliation: Public Health Agency of Canada.
authors.forename: Louise
authors.initials: L
authors.lastname: McRae
mesh_terms: D000328:Adult; D000368:Aged; D000402:Airway Obstruction / Q000453:epidemiology / Q000503:physiopathology; D002170:Canada / Q000453:epidemiology; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology* / Q000503:physiopathology*; D012129:Respiratory Function Tests; D012307:Risk Factors; D057566:Self Report
keywords: Chronic bronchitis; lung volume measurements; smoking; spirometry