Characterisation of COPD heterogeneity in the ECLIPSE cohort.
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.
Agusti
Alvar
A
Thorax Institute, Hospital Clinic, IDIBAPS, Universitat de Barcelona, Spain. alvar.agusti@clinic.ub.es
Calverley
Peter M A
PM
Celli
Bartolome
B
Coxson
Harvey O
HO
Edwards
Lisa D
LD
Lomas
David A
DA
MacNee
William
W
Miller
Bruce E
BE
Rennard
Steve
S
Silverman
Edwin K
EK
Tal-Singer
Ruth
R
Wouters
Emiel
E
Yates
Julie C
JC
Vestbo
Jørgen
J
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*