title: Seven-year cumulative incidence of COPD in an age-stratified general population sample.
abstract: OBJECTIVE
  To estimate the cumulative incidence of COPD and risk factors related to the development of COPD, including evaluation of the relationship between Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 0 (ie, respiratory symptoms and normal lung function) and the development of COPD, in an age-stratified general population sample of middle-aged and elderly individuals.
  
  
  METHODS
  The third survey of the Obstructive Lung Disease in Northern Sweden studies cohort I (three age strata born in 1919 to 1920, 1934 to 1935, and 1949 to 1950) was performed in 1996, and 5,189 subjects (88%) responded to the postal questionnaire. Of the responders, a random sample (1,500 subjects) was invited to an examination in 1996 and in 2003. A total of 963 subjects performed spirometry on both occasions. COPD was defined according to the spirometric criteria of the GOLD. Two levels of disease severity, grade I and higher (GOLD criteria, FEV(1)/FVC ratio of < 0.70) and also grade II and higher (GOLD II criteria, FEV(1)/FVC ratio of < 0.70 and FEV(1) <80% predicted).
  
  
  RESULTS
  The 7-year cumulative incidence of COPD was 11.0% and 4.9%, respectively, according to GOLD and GOLD II, and was significantly related to smoking (smokers, 18.8% and 10.6%, respectively; ex-smokers, 10.5% and 5.2%, respectively; non-smokers, 7.6% and 1.6%, respectively). Incident COPD according to GOLD, but not according to GOLD II, was significantly associated with increasing age. Most respiratory symptoms at study entry were markers of increased risk for incident COPD when analyzed in a multivariate model adjusting for confounders.
  
  
  CONCLUSIONS
  The GOLD criteria yielded a higher cumulative incidence (11.0%) compared to the GOLD II (4.9%). Smoking, but not gender, was associated with incident COPD. Most respiratory symptoms at the beginning of the observation period marked an increased risk for developing COPD, thus the classification GOLD stage 0 seems relevant among middle-aged and elderly persons.
authors.affiliation: Senior Consultant, Division of Respiratory Medicine and Allergy, Department of Medicine, Sunderby Central Hospital of Norrbotten, SE-971 80 Luleå, Sweden. anne.lindberg@algmed.se
authors.forename: Anne
authors.initials: A
authors.lastname: Lindberg
authors.forename: Berne
authors.initials: B
authors.lastname: Eriksson
authors.forename: Lars-Gunnar
authors.initials: LG
authors.lastname: Larsson
authors.forename: Eva
authors.initials: E
authors.lastname: Rönmark
authors.forename: Thomas
authors.initials: T
authors.lastname: Sandström
authors.forename: Bo
authors.initials: B
authors.lastname: Lundbäck
mesh_terms: D017677:Age Distribution; D000368:Aged; D015331:Cohort Studies; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000453:epidemiology* / Q000503:physiopathology; D012307:Risk Factors; D012720:Severity of Illness Index; D013147:Spirometry; D013548:Sweden / Q000453:epidemiology; D014797:Vital Capacity / Q000502:physiology