title: Prevalence and risk factors of COPD among never-smokers in two areas of Sweden - Occupational exposure to gas, dust or fumes is an important risk factor.
abstract: BACKGROUND
  Although active tobacco smoking is the main risk factor for COPD, COPD is not uncommon also among never-smokers. Different study locations along with different spirometric definitions of COPD have historically yielded different prevalence estimates of the disease.
  
  
  OBJECTIVE
  To study current prevalence and risk factors of COPD among never-smokers in two areas of Sweden.
  
  
  METHODS
  Data collected in 2008-2012 within the West Sweden Asthma Study and Obstructive Lung Disease in Northern Sweden Studies was pooled. The study population consisted of 1839 subjects who participated in spirometry and interviews. COPD was defined as post-bronchodilator a) FEV(1)/(F)VC < 0.7, b) FEV(1)/FVC < 0.7 and c) FEV(1)/FVC < lower limit of normal.
  
  
  RESULTS
  Of the 1839 subjects, 967 (52.6%) were never-smokers. Among the never-smoking subjects, the prevalence of COPD according to definitions a-c was 7.7%, 4.9% and 3.0%, respectively. The corresponding prevalence of GOLD grade ≥2 was 2.0%, 1.4% and 1.3%. No significant difference in prevalence between the two study areas was observed. In never-smokers, occupational exposure to gas, dust or fumes (GDF) was significantly associated with both COPD (OR 1.85, 95% CI 1.03-3.33), and GOLD ≥2 (OR 4.51, 1.72-11.9) according to definition a), after adjusting for age, educational level and exposure to passive smoking at work.
  
  
  CONCLUSIONS
  Depending on definition, prevalence of COPD among never-smokers was 3.0-7.7%, whereas GOLD ≥2 was present in 1.3-2.0%. Occupational exposure to GDF remained independently and significantly associated with COPD regardless of spirometric definition of the disease.
authors.affiliation: Krefting Research Centre, University of Gothenburg, Gothenburg, Sweden; Obstructive Lung Disease In Northern Sweden (OLIN) Studies, Norrbotten County Council, Luleå, Sweden. Electronic address: stig.hagstad@gu.se.
authors.forename: Stig
authors.initials: S
authors.lastname: Hagstad
authors.affiliation: Obstructive Lung Disease In Northern Sweden (OLIN) Studies, Norrbotten County Council, Luleå, Sweden; Division of Occupational and Environmental Medicine, The OLIN Unit, Umeå University, Sweden.
authors.forename: Helena
authors.initials: H
authors.lastname: Backman
authors.affiliation: Krefting Research Centre, University of Gothenburg, Gothenburg, Sweden; Obstructive Lung Disease In Northern Sweden (OLIN) Studies, Norrbotten County Council, Luleå, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Bjerg
authors.affiliation: Krefting Research Centre, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Linda
authors.initials: L
authors.lastname: Ekerljung
authors.affiliation: Krefting Research Centre, University of Gothenburg, Gothenburg, Sweden; Department of Respiratory Medicine, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, Shanghai, China; Medical College of Soocuow University, Su Zhou, China.
authors.forename: Xiong
authors.initials: X
authors.lastname: Ye
authors.affiliation: Obstructive Lung Disease In Northern Sweden (OLIN) Studies, Norrbotten County Council, Luleå, Sweden; Division of Occupational and Environmental Medicine, The OLIN Unit, Umeå University, Sweden.
authors.forename: Linnea
authors.initials: L
authors.lastname: Hedman
authors.affiliation: Division of Medicine, Department of Public Health and Clinical Medicine, Umeå University, Sweden.
authors.forename: Anne
authors.initials: A
authors.lastname: Lindberg
authors.affiliation: Section of Occupational and Environmental Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Kjell
authors.initials: K
authors.lastname: Torén
authors.affiliation: Krefting Research Centre, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Lötvall
authors.affiliation: Obstructive Lung Disease In Northern Sweden (OLIN) Studies, Norrbotten County Council, Luleå, Sweden; Division of Occupational and Environmental Medicine, The OLIN Unit, Umeå University, Sweden.
authors.forename: Eva
authors.initials: E
authors.lastname: Rönmark
authors.affiliation: Krefting Research Centre, University of Gothenburg, Gothenburg, Sweden; Obstructive Lung Disease In Northern Sweden (OLIN) Studies, Norrbotten County Council, Luleå, Sweden.
authors.forename: Bo
authors.initials: B
authors.lastname: Lundbäck
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000395:Air Pollutants, Occupational / Q000009:adverse effects*; D015897:Comorbidity; D004391:Dust; D005740:Gases / Q000009:adverse effects; D006801:Humans; D008875:Middle Aged; D009784:Occupational Diseases / Q000453:epidemiology* / Q000209:etiology; D016273:Occupational Exposure / Q000009:adverse effects*; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology* / Q000209:etiology; D012307:Risk Factors; D012680:Sensitivity and Specificity; D017678:Sex Distribution; D012907:Smoking / Q000453:epidemiology; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000395:Air Pollutants, Occupational; D004391:Dust; D005740:Gases
keywords: COPD; Epidemiology; Never smokers; Population study; Risk factors