title: Proportional classifications of COPD phenotypes.
abstract: BACKGROUND
  Chronic obstructive pulmonary disease (COPD) encompasses a group of disorders characterised by the presence of incompletely reversible airflow obstruction with overlapping subsets of different phenotypes including chronic bronchitis, emphysema or asthma. The aim of this study was to determine the proportion of adult subjects aged >50 years within each phenotypic subgroup of COPD, defined as a post-bronchodilator ratio of forced expiratory volume in 1 s/forced vital capacity (FEV(1)/FVC) <0.7, in accordance with current international guidelines.
  
  
  METHODS
  Adults aged >50 years derived from a random population-based survey undertook detailed questionnaires, pulmonary function tests and chest CT scans. The proportion of subjects in each of 16 distinct phenotypes was determined based on combinations of chronic bronchitis, emphysema and asthma, with and without incompletely reversible airflow obstruction defined by a post-bronchodilator FEV(1)/FVC ratio of 0.7.
  
  
  RESULTS
  A total of 469 subjects completed the investigative modules, 96 of whom (20.5%) had COPD. Diagrams were constructed to demonstrate the relative proportions of the phenotypic subgroups in subjects with and without COPD. 18/96 subjects with COPD (19%) had the classical phenotypes of chronic bronchitis and/or emphysema but no asthma; asthma was the predominant COPD phenotype, being present in 53/96 (55%). When COPD was defined as a post-bronchodilator FEV(1)/FVC less than the lower limit of normal, there were one-third fewer subjects with COPD and a smaller proportion without a defined emphysema, chronic bronchitis or asthma phenotype.
  
  
  CONCLUSIONS
  This study provides proportional classifications of the phenotypic subgroups of COPD which can be used as the basis for further research into the pathogenesis and treatment of this heterogeneous disorder.
authors: Medical Research Institute of New Zealand, P O Box 10055, Wellington 6143, New Zealand. richard.beasley@mrinz.ac.nz
authors: S E
authors: SE
authors: Marsh
authors: J
authors: J
authors: Travers
authors: M
authors: M
authors: Weatherall
authors: M V
authors: MV
authors: Williams
authors: S
authors: S
authors: Aldington
authors: P M
authors: PM
authors: Shirtcliffe
authors: A L
authors: AL
authors: Hansell
authors: M R
authors: MR
authors: Nowitz
authors: A A
authors: AA
authors: McNaughton
authors: J B
authors: JB
authors: Soriano
authors: R W
authors: RW
authors: Beasley
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D001249:Asthma / Q000175:diagnosis; D029481:Bronchitis, Chronic / Q000175:diagnosis; D001993:Bronchodilator Agents; D003937:Diagnosis, Differential; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D010641:Phenotype; D029424:Pulmonary Disease, Chronic Obstructive / Q000145:classification / Q000175:diagnosis* / Q000503:physiopathology; D011656:Pulmonary Emphysema / Q000175:diagnosis; D014797:Vital Capacity / Q000502:physiology
chemical_list: D001993:Bronchodilator Agents