Chest
Volume 147, Issue 5, May 2015, Pages 1235-1245
Journal home page for Chest

Original Research: COPD
Physiologic Characterization of the Chronic Bronchitis Phenotype in GOLD Grade IB COPD

https://doi.org/10.1378/chest.14-1491Get rights and content

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.

Section snippets

Subjects

Forty patients with symptomatic COPD fitting GOLD grade IB criteria (a postbronchodilator FEV1 ≥ 80% predicted and an FEV1/FVC < 0.7 and less than lower limit of normal25; none to one exacerbation per year; and modified Medical Research Council dyspnea scale ≥ 2 or COPD Assessment Test [CAT] score ≥ 10)2 were categorized into two groups (n = 20 each) based on having CB or not (non-CB).6 Inclusion criteria included age ≥ 50 years and a smoking history of ≥ 20 pack-years. Exclusion criteria

Results

All groups had similar sex distribution, age, height, weight, and BMI (Table 1). The COPD groups had similar smoking history and medication use, except more patients with CB used a long-acting muscarinic antagonist. Both COPD groups were more symptomatic compared with the healthy group. However, the CB group had greater chronic, activity-related dyspnea, higher CAT scores, lower physical activity according to Community Healthy Activities Model Program for Seniors (CHAMPS), poorer health status

Discussion

The main findings of this study are the following: (1) patients with CB had greater chronic activity-related dyspnea and poorer perceived health status than patients without CB who had similar spirometric abnormalities; (2) both CB and non-CB groups had extensive but comparable peripheral airway dysfunction at rest; and (3) exercise tolerance was similarly reduced in both COPD groups, but those with CB experienced greater exertional dyspnea and dynamic respiratory mechanical constraints than

Conclusions

This study provides the first comprehensive, physiologic characterization of CB in smokers with only minor spirometric abnormalities. Patients with CB experienced greater chronic activity-related dyspnea and poorer health-related quality of life than patients without CB. Both mild COPD groups had extensive peripheral airway dysfunction, dynamic respiratory mechanical abnormalities, and reduced exercise tolerance. Those with CB had greater mechanical constraints and a greater disparity between

Acknowledgments

Author contributions: D. E. O. was the principal investigator and takes responsibility for the integrity of the data and the accuracy of the data analysis. D. E. O. contributed to the study concept; A. F. E., N. R., K. A. W., and D. E. O. contributed to the study design; A. F. E., N. R., K. A. W., J. A. N., M. I. M., and D. E. O. contributed to the conduct of the study; A. F. E., N. R., S. C., L. Y., K. A. W., and J. A. G. contributed to data collection; A. F. E. and K. A. W. contributed to the

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    FUNDING/SUPPORT: This study was supported by the William Spear Endowment Fund/Start Memorial Fund, Queen's University and the Canadian Respiratory Research Network. Financial support to Dr Elbehairy was provided by an Egyptian Ministry of Higher Education and Scientific Research Scholarship.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.

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