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Thorax. 2015 Sep;70(9):822-9. doi: 10.1136/thoraxjnl-2015-206938. Epub 2015 Jun 5.

Characteristics of COPD in never-smokers and ever-smokers in the general population: results from the CanCOLD study.

Author information

1
University of British Columbia, Heart Lung Innovation, Vancouver, British Columbia, Canada.
2
Respiratory Epidemiology and Clinical Research Unit, Montreal Chest Institute, McGill University Health Centre, McGill University, Montréal, Quebec, Canada.
3
Department of Medicine, QEII Health Sciences Centre, Dalhousie University, Halifax, Nova Scotia, Canada.
4
Department of Respiratory Medicine, University of Toronto, Toronto, Ontario, Canada.
5
Departments of Medicine and Community Health Sciences, University of Calgary, Calgary, Alberta, Canada.
6
Department of Respiratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
7
Department of Respiratory Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
8
Centre de Pneumologie de l'Hopital Laval, Respirology, Quebec City, Quebec, Canada.
9
Oregon Health Sciences University, Portland, Oregon, USA.
10
Department of Radiology, St Paul's Hospital, Vancouver, British Columbia, Canada.
11
University of British Columbia, Heart Lung Innovation, Vancouver, British Columbia, Canada Respiratory Epidemiology and Clinical Research Unit, Montreal Chest Institute, McGill University Health Centre, McGill University, Montréal, Quebec, Canada Department of Medicine, QEII Health Sciences Centre, Dalhousie University, Halifax, Nova Scotia, Canada Department of Respiratory Medicine, University of Toronto, Toronto, Ontario, Canada Departments of Medicine and Community Health Sciences, University of Calgary, Calgary, Alberta, Canada Department of Respiratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada Department of Respiratory Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada Centre de Pneumologie de l'Hopital Laval, Respirology, Quebec City, Quebec, Canada. Oregon Health Sciences University, Portland, Oregon, USA Department of Radiology, St Paul's Hospital, Vancouver, British Columbia, Canada Department of Medicine/Physiology, Queens University, Kingston, Ontario, Canada Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada.
12
Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada.

Abstract

BACKGROUND:

There is limited data on the risk factors and phenotypical characteristics associated with spirometrically confirmed COPD in never-smokers in the general population.

AIMS:

To compare the characteristics associated with COPD by gender and by severity of airway obstruction in never-smokers and in ever-smokers.

METHOD:

We analysed the data from 5176 adults aged 40 years and older who participated in the initial cross-sectional phase of the population-based, prospective, multisite Canadian Cohort of Obstructive Lung Disease study. Never-smokers were defined as those with a lifetime exposure of <1/20 pack year. Logistic regressions were constructed to evaluate associations for 'mild' and 'moderate-severe' COPD defined by FEV1/FVC <5th centile (lower limits of normal). Analyses were performed using SAS V.9.1 (SAS Institute, Cary, North Carolina, USA).

RESULTS:

The prevalence of COPD (FEV1/FVC<lower limits of normal) in never-smokers was 6.4%, constituting 27% of all COPD subjects. The common independent predictors of COPD in never-smokers and ever-smokers were older age, self reported asthma and lower education. In never-smokers a history of hospitalisation in childhood for respiratory illness was discriminative, while exposure to passive smoke and biomass fuel for heating were discriminative for women. COPD in never-smokers and ever-smokers was characterised by increased respiratory symptoms, 'respiratory exacerbation' events and increased residual volume/total lung capacity, but only smokers had reduced DLCO/Va and emphysema on chest CT scans.

CONCLUSIONS:

The study confirmed the substantial burden of COPD among never-smokers, defined the common and gender-specific risk factors for COPD in never-smokers and provided early insight into potential phenotypical differences in COPD between lifelong never-smokers and ever-smokers.

TRIAL REGISTRATION NUMBER:

NCT00920348 (ClinicalTrials.gov); study ID number: IRO-93326.

KEYWORDS:

COPD epidemiology; Clinical Epidemiology

PMID:
26048404
DOI:
10.1136/thoraxjnl-2015-206938
[Indexed for MEDLINE]

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