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Background
Keywords
Findings
Author
What is already known on this subject?
What does this study add?

Text begins

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.

Data and 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.

Interpretation

This study suggests that the prevalence of COPD in Canada has been underestimated.

Keywords

Chronic bronchitis, lung volume measurements, smoking, spirometry

Findings

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality in Canada. COPD is typically described in terms of two conditions—chronic bronchitis and emphysema—although asthma and other causes of chronic airflow obstruction are often included. National estimates of COPD prevalence are approximately 4%, based on survey respondents' reports of having been diagnosed with the condition. However, these estimates were not derived from objective lung function measures, and so are suspected to under-represent the true prevalence of COPD. [Full Text]

Author

Jessica Evans (jessica.evans@mail.mcgill.ca) was formerly with the Public Health Agency of Canada, Ottawa, Ontario. Louise McRae is with the Public Health Agency of Canada. Yue Chen is with the University of Ottawa. Pat G. Camp is with the University of British Columbia. Dennis M. Bowie is with Dalhousie University.

What is already known on this subject?

  • Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality in Canada.
  • Self-reports of a diagnosis may underestimate the prevalence of COPD.

What does this study add?

  • The measured prevalence of airflow obstruction was two to six times higher than estimates based on self-reports of having been diagnosed with COPD by a health professional.
  • Agreement between self-reported diagnosed COPD and measures of airflow obstruction was minimal.
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