Cluster Analysis in Patients with GOLD 1 Chronic Obstructive Pulmonary Disease.

• Main Authors: Philippe Gagnon, Richard Casaburi, Didier Saey, Janos Porszasz, Steeve Provencher, Julie Milot, Jean Bourbeau, Denis E O'Donnell, François Maltais
• Format: Article
• Language: English
• Published: Public Library of Science (PLoS) 2015-01-01
• Series: PLoS ONE
• Online Access: https://doi.org/10.1371/journal.pone.0123626

<h4>Background</h4>We hypothesized that heterogeneity exists within the Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1 spirometric category and that different subgroups could be identified within this GOLD category.<h4>Methods</h4>Pre-randomization study participants from two clinical trials were symptomatic/asymptomatic GOLD 1 chronic obstructive pulmonary disease (COPD) patients and healthy controls. A hierarchical cluster analysis used pre-randomization demographics, symptom scores, lung function, peak exercise response and daily physical activity levels to derive population subgroups.<h4>Results</h4>Considerable heterogeneity existed for clinical variables among patients with GOLD 1 COPD. All parameters, except forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC), had considerable overlap between GOLD 1 COPD and controls. Three-clusters were identified: cluster I (18 [15%] COPD patients; 105 [85%] controls); cluster II (45 [80%] COPD patients; 11 [20%] controls); and cluster III (22 [92%] COPD patients; 2 [8%] controls). Apart from reduced diffusion capacity and lower baseline dyspnea index versus controls, cluster I COPD patients had otherwise preserved lung volumes, exercise capacity and physical activity levels. Cluster II COPD patients had a higher smoking history and greater hyperinflation versus cluster I COPD patients. Cluster III COPD patients had reduced physical activity versus controls and clusters I and II COPD patients, and lower FEV1/FVC versus clusters I and II COPD patients.<h4>Conclusions</h4>The results emphasize heterogeneity within GOLD 1 COPD, supporting an individualized therapeutic approach to patients.<h4>Trial registration</h4>www.clinicaltrials.gov. NCT01360788 and NCT01072396.