title: Characterisation of COPD heterogeneity in the ECLIPSE cohort.
abstract: BACKGROUND
  Chronic obstructive pulmonary disease (COPD) is a complex condition with pulmonary and extra-pulmonary manifestations. This study describes the heterogeneity of COPD in a large and well characterised and controlled COPD cohort (ECLIPSE).
  
  
  METHODS
  We studied 2164 clinically stable COPD patients, 337 smokers with normal lung function and 245 never smokers. In these individuals, we measured clinical parameters, nutritional status, spirometry, exercise tolerance, and amount of emphysema by computed tomography.
  
  
  RESULTS
  COPD patients were slightly older than controls and had more pack years of smoking than smokers with normal lung function. Co-morbidities were more prevalent in COPD patients than in controls, and occurred to the same extent irrespective of the GOLD stage. The severity of airflow limitation in COPD patients was poorly related to the degree of breathlessness, health status, presence of co-morbidity, exercise capacity and number of exacerbations reported in the year before the study. The distribution of these variables within each GOLD stage was wide. Even in subjects with severe airflow obstruction, a substantial proportion did not report symptoms, exacerbations or exercise limitation. The amount of emphysema increased with GOLD severity. The prevalence of bronchiectasis was low (4%) but also increased with GOLD stage. Some gender differences were also identified.
  
  
  CONCLUSIONS
  The clinical manifestations of COPD are highly variable and the degree of airflow limitation does not capture the heterogeneity of the disease.
authors.affiliation: Thorax Institute, Hospital Clinic, IDIBAPS, Universitat de Barcelona, Spain. alvar.agusti@clinic.ub.es
authors.forename: Alvar
authors.initials: A
authors.lastname: Agusti
authors.forename: Peter M A
authors.initials: PM
authors.lastname: Calverley
authors.forename: Bartolome
authors.initials: B
authors.lastname: Celli
authors.forename: Harvey O
authors.initials: HO
authors.lastname: Coxson
authors.forename: Lisa D
authors.initials: LD
authors.lastname: Edwards
authors.forename: David A
authors.initials: DA
authors.lastname: Lomas
authors.forename: William
authors.initials: W
authors.lastname: MacNee
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Miller
authors.forename: Steve
authors.initials: S
authors.lastname: Rennard
authors.forename: Edwin K
authors.initials: EK
authors.lastname: Silverman
authors.forename: Ruth
authors.initials: R
authors.lastname: Tal-Singer
authors.forename: Emiel
authors.initials: E
authors.lastname: Wouters
authors.forename: Julie C
authors.initials: JC
authors.lastname: Yates
authors.forename: Jørgen
authors.initials: J
authors.lastname: Vestbo
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology*; D012129:Respiratory Function Tests / Q000379:methods; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology*