title: Incidence of GOLD-defined chronic obstructive pulmonary disease in a general adult population.
abstract: METHODS
  The incidence of chronic obstructive pulmonary disease (COPD) as defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) has not previously been examined.
  
  
  OBJECTIVE
  To estimate cumulative 9-year GOLD-defined COPD incidence in a general adult Norwegian population, to analyse sex, age, smoking habits and residential area as predictors, and to assess the level of underdiagnosis.
  
  
  METHODS
  Based on a random stratified population sample examined in 1987-1988, 908 adults (71%) participated in a follow-up examination in 1996-1997. Associations between risk factors and COPD incidence were examined with logistic regression analyses.
  
  
  RESULTS
  The cumulative incidence of COPD among persons at risk in 1987-1988 was 6.1% (95% confidence interval [CI] 4.0-8.1). Adjusted odds ratios (OR) for current smokers and ex-smokers were 9.6 (95% CI 3.6-25.2) and 5.0 (95% CI 1.8-13.8), compared to never smokers. Risk for COPD incidence further increased with pack years. Subjects aged 45-74 had an OR of 9.8 (95% CI 4.3-22.5) relative to those aged 18-44. Sex and residential area were not significantly associated with COPD incidence. Only 43% of the incident cases had physician-diagnosed asthma, bronchitis, emphysema and/or COPD.
  
  
  CONCLUSIONS
  Approximately 6% developed COPD over 9 years. Smoking and aging were important incidence predictors. Our study suggests a substantial underdiagnosis of COPD among adults in this community.
authors.affiliation: Institute of Medicine, University of Bergen, Bergen, Norway. Ane.Johannessen@helse-bergen.no
authors.forename: A
authors.initials: A
authors.lastname: Johannessen
authors.forename: E
authors.initials: E
authors.lastname: Omenaas
authors.forename: P
authors.initials: P
authors.lastname: Bakke
authors.forename: A
authors.initials: A
authors.lastname: Gulsvik
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D016017:Odds Ratio; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000453:epidemiology*; D012016:Reference Values; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects