Physiologic characterization of the chronic bronchitis phenotype in GOLD grade IB COPD.
BACKGROUND
Smokers with persistent cough and sputum production (chronic bronchitis [CB]) represent a distinct clinical phenotype, consistently linked to negative clinical outcomes. However, the mechanistic link between physiologic impairment, dyspnea, and exercise intolerance in CB has not been studied, particularly in those with mild airway obstruction. We, therefore, compared physiologic abnormalities during rest and exercise in CB to those in patients without symptoms of mucus hypersecretion (non-CB) but with similar mild airway obstruction.


METHODS
Twenty patients with CB (≥ 3 months cough/sputum in 2 successive years), 20 patients without CB but with GOLD (Global Initiative for Chronic Obstructive Lung Disease) grade IB COPD, and 20 age- and sex-matched healthy control subjects underwent detailed physiologic testing, including tests of small airway function and a symptom-limited incremental cycle exercise test.


RESULTS
Patients with CB (mean ± SD postbronchodilator FEV1, 93% ± 12% predicted) had greater chronic activity-related dyspnea, poorer health-related quality of life, and reduced habitual physical activity compared with patients without CB and control subjects (all P < .05). The degree of peripheral airway dysfunction and pulmonary gas trapping was comparable in both patient groups. Peak oxygen uptake was similarly reduced in patients with CB and those without compared with control subjects (% predicted ± SD, 70 ± 26, 71 ± 29 and 106 ± 43, respectively), but those with CB had higher exertional dyspnea ratings and greater respiratory mechanical constraints at a standardized work rate than patients without CB (P < .05).


CONCLUSIONS
Patients with CB reported greater chronic dyspnea and activity restriction than patients without CB and with similar mild airway obstruction. The CB group had greater dynamic respiratory mechanical impairment and dyspnea during exercise than patients without CB, which may help explain some differences in important patient-centered outcomes between the groups.
Department of Medicine, Department of Chest Diseases, Faculty of Medicine, Alexandria University, Alexandria, Egypt.
Amany F
AF
Elbehairy
Department of Medicine, McMaster University, Hamilton, ON, Canada.
Natya
N
Raghavan
Department of Medicine, Department of Chest Diseases, Queen's University & Kingston General Hospital, Kingston, ON, Canada.
Sicheng
S
Cheng
Department of Medicine, Department of Chest Diseases, Faculty of Medicine, Alexandria University, Alexandria, Egypt.
Ling
L
Yang
Department of Medicine, Department of Chest Diseases, Queen's University & Kingston General Hospital, Kingston, ON, Canada.
Katherine A
KA
Webb
Department of Medicine, Department of Chest Diseases, Queen's University & Kingston General Hospital, Kingston, ON, Canada.
J Alberto
JA
Neder
Department of Physical Therapy and UBC Centre for Heart Lung Innovation, University of British Columbia, Vancouver, BC, Canada.
Jordan A
JA
Guenette
Department of Chest Diseases, Faculty of Medicine, Alexandria University, Alexandria, Egypt.
Mahmoud I
MI
Mahmoud
Department of Medicine, Department of Chest Diseases, Queen's University & Kingston General Hospital, Kingston, ON, Canada.
Denis E
DE
O'Donnell
D000368:Aged; D029481:Bronchitis, Chronic / Q000150:complications* / Q000235:genetics / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D029424:Pulmonary Disease, Chronic Obstructive / Q000145:classification / Q000150:complications* / Q000503:physiopathology*; D012720:Severity of Illness Index