COPD in never smokers: results from the population-based burden of obstructive lung disease study.
BACKGROUND
Never smokers comprise a substantial proportion of patients with COPD. Their characteristics and possible risk factors in this population are not yet well defined.


METHODS
We analyzed data from 14 countries that participated in the international, population-based Burden of Obstructive Lung Disease (BOLD) study. Participants were aged ≥ 40 years and completed postbronchodilator spirometry testing plus questionnaires about respiratory symptoms, health status, and exposure to COPD risk factors. A diagnosis of COPD was based on the postbronchodilator FEV₁/FVC ratio, according to current GOLD (Global Initiative for Obstructive Lung Disease) guidelines. In addition to this, the lower limit of normal (LLN) was evaluated as an alternative threshold for the FEV₁/FVC ratio.


RESULTS
Among 4,291 never smokers, 6.6% met criteria for mild (GOLD stage I) COPD, and 5.6% met criteria for moderate to very severe (GOLD stage II+) COPD. Although never smokers were less likely to have COPD and had less severe COPD than ever smokers, never smokers nonetheless comprised 23.3% (240/1,031) of those classified with GOLD stage II+ COPD. This proportion was similar, 20.5% (171/832), even when the LLN was used as a threshold for the FEV₁/FVC ratio. Predictors of COPD in never smokers include age, education, occupational exposure, childhood respiratory diseases, and BMI alterations.


CONCLUSIONS
This multicenter international study confirms previous evidence that never smokers comprise a substantial proportion of individuals with COPD. Our data suggest that, in addition to increased age, a prior diagnosis of asthma and, among women, lower education levels are associated with an increased risk for COPD among never smokers.
Lamprecht
Bernd
B
Department of Pulmonary Medicine, Paracelsus Medical University, Salzburg, Austria. Electronic address: b.lamprecht@salk.at.
McBurnie
Mary Ann
MA
Kaiser Permanente Center for Health Research, University, Portland.
Vollmer
William M
WM
Kaiser Permanente Center for Health Research, University, Portland.
Gudmundsson
Gunnar
G
Department of Respiratory Medicine, Allergy, and Sleep, Landspitali University Hospital, Reykjavik, Iceland.
Welte
Tobias
T
Department of Respiratory Medicine, Hannover Medical University, Hannover, Germany.
Nizankowska-Mogilnicka
Ewa
E
Department of Medicine, Jagiellonian University School of Medicine, Krakow, Poland.
Studnicka
Michael
M
Department of Pulmonary Medicine, Paracelsus Medical University, Salzburg, Austria.
Bateman
Eric
E
University of Cape Town, Cape Town, South Africa.
Anto
Josep M
JM
Centre for Research in Environmental Epidemiology, Barcelona, Spain.
Burney
Peter
P
Department of Public Health Sciences, King's College London, London, England.
Mannino
David M
DM
University of Kentucky, Lexington, KY.
Buist
Sonia A
SA
Oregon Health and Science University, Portland.
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D014943:Global Health; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology* / Q000503:physiopathology; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D012307:Risk Factors; D012907:Smoking; D011795:Surveys and Questionnaires