Factor analysis in predominantly severe COPD: Identification of disease heterogeneity by easily measurable characteristics

Dirkje S. Postma, Antonio R. Anzueto, Christine Jenkins, Barry J. Make, Thomas Similowski, Ollie Östlund, Göran S. Eriksson, Peter M. Calverley

Resultado de la investigación: Articlerevisión exhaustiva

6 Citas (Scopus)


Background The clinical and demographic variables defining the heterogeneity of chronic obstructive pulmonary disease (COPD) are unclear. A post-hoc analysis of five randomised studies in patients with a history of previous exacerbations examined the clinical and demographic characteristics describing moderate-to-very-severe COPD. Methods Factor analysis was performed on all continuous baseline demographic and clinical data, without variable selection. Analyses were based on the full cohort and on stratifications by pack-years smoked, smoking status, gender, and comorbidities; patient exacerbation history was analysed in two of the five studies. Findings 6162 COPD patients were evaluated (70% male; 40% current smokers; mean pre-bronchodilator forced expiratory volume in 1 s [FEV1] 35.2% predicted). Baseline clinical and demographic variables loaded differentially on six factors with minimal overlap, explaining 60.4% of the heterogeneity: 1) symptoms (cough, dyspnoea, sleep disturbance), health status, reliever use; 2) pre-bronchodilator FEV1, FEV1/forced vital capacity, morning peak expiratory flow (PEF), body mass index (BMI); 3) blood pressure; 4) age, months since first COPD symptoms; 5) PEF variability; 6) pulse, FEV1 reversibility. Most factors loaded similarly in stratified and exacerbation analyses. BMI loaded with reversibility in females, and with age and months since first COPD symptoms in ex-smokers. Exacerbations loaded to factor 6. Interpretation Readily available data can explain ∼60% of COPD heterogeneity in a large dataset of predominantly severe COPD patients. Factors were robust over determinants of disease outcome; gender, smoking status, pack-years smoked, and comorbidities. The main factors were largely unchanged by adding exacerbations. Only BMI loaded to other factors.

Idioma originalEnglish (US)
Páginas (desde-hasta)1939-1947
Número de páginas9
PublicaciónRespiratory Medicine
EstadoPublished - dic 2013

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine


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