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JAMA. 2016 Feb 2;315(5):498-505. doi: 10.1001/jama.2015.19431.

Association Between Expiratory Central Airway Collapse and Respiratory Outcomes Among Smokers.

Author information

1
Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham2UAB Lung Health Center, University of Alabama at Birmingham3UAB Lung Imaging Core, University of Alabama at Birmingham.
2
UAB Lung Imaging Core, University of Alabama at Birmingham4Department of Radiology, University of Alabama at Birmingham.
3
Quantitative Imaging Laboratory, National Jewish Health, Denver, Colorado.
4
VIDA Diagnostics, Coralville, Iowa.
5
Department of Radiology, National Jewish Health, Denver, Colorado.
6
Department of Biostatistics and Bioinformatics, National Jewish Health, Denver, Colorado.
7
Quantitative Imaging Laboratory, National Jewish Health, Denver, Colorado7Department of Radiology, National Jewish Health, Denver, Colorado.
8
Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland.
9
Division of Pulmonary, Critical Care and Sleep Medicine, University of California San Diego.
10
Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
11
Department of Radiology and Biomedical Engineering, University of Iowa Carver College of Medicine, Iowa City.
12
Division of Pulmonary and Critical Care Medicine, Morehouse School of Medicine, Atlanta, Georgia.
13
Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham2UAB Lung Health Center, University of Alabama at Birmingham3UAB Lung Imaging Core, University of Alabama at Birmingham14Veterans Affairs Medical Center, Birming.

Abstract

IMPORTANCE:

Central airway collapse greater than 50% of luminal area during exhalation (expiratory central airway collapse [ECAC]) is associated with cigarette smoking and chronic obstructive pulmonary disease (COPD). However, its prevalence and clinical significance are unknown.

OBJECTIVE:

To determine whether ECAC is associated with respiratory morbidity in smokers independent of underlying lung disease.

DESIGN, SETTING, AND PARTICIPANTS:

Analysis of paired inspiratory-expiratory computed tomography images from a large multicenter study (COPDGene) of current and former smokers from 21 clinical centers across the United States. Participants were enrolled from January 2008 to June 2011 and followed up longitudinally until October 2014. Images were initially screened using a quantitative method to detect at least a 30% reduction in minor axis tracheal diameter from inspiration to end-expiration. From this sample of screen-positive scans, cross-sectional area of the trachea was measured manually at 3 predetermined levels (aortic arch, carina, and bronchus intermedius) to confirm ECAC (>50% reduction in cross-sectional area).

EXPOSURES:

Expiratory central airway collapse.

MAIN OUTCOMES AND MEASURES:

The primary outcome was baseline respiratory quality of life (St George's Respiratory Questionnaire [SGRQ] scale 0 to 100; 100 represents worst health status; minimum clinically important difference [MCID], 4 units). Secondary outcomes were baseline measures of dyspnea (modified Medical Research Council [mMRC] scale 0 to 4; 4 represents worse dyspnea; MCID, 0.7 units), baseline 6-minute walk distance (MCID, 30 m), and exacerbation frequency (events per 100 person-years) on longitudinal follow-up.

RESULTS:

The study included 8820 participants with and without COPD (mean age, 59.7 [SD, 6.9] years; 4667 [56.7%] men; 4559 [51.7%] active smokers). The prevalence of ECAC was 5% (443 cases). Patients with ECAC compared with those without ECAC had worse SGRQ scores (30.9 vs 26.5 units; P < .001; absolute difference, 4.4 [95% CI, 2.2-6.6]) and mMRC scale scores (median, 2 [interquartile range [IQR], 0-3]) vs 1 [IQR, 0-3]; P < .001]), but no significant difference in 6-minute walk distance (399 vs 417 m; absolute difference, 18 m [95% CI, 6-30]; P = .30), after adjustment for age, sex, race, body mass index, forced expiratory volume in the first second, pack-years of smoking, and emphysema. On follow-up (median, 4.3 [IQR, 3.2-4.9] years), participants with ECAC had increased frequency of total exacerbations (58 vs 35 events per 100 person-years; incidence rate ratio [IRR], 1.49 [95% CI, 1.29-1.72]; P < .001) and severe exacerbations requiring hospitalization (17 vs 10 events per 100 person-years; IRR, 1.83 [95% CI, 1.51-2.21]; P < .001).

CONCLUSIONS AND RELEVANCE:

In a cross-sectional analysis of current and former smokers, the presence of ECAC was associated with worse respiratory quality of life. Further studies are needed to assess long-term associations with clinical outcomes.

PMID:
26836732
PMCID:
PMC5173387
DOI:
10.1001/jama.2015.19431
[Indexed for MEDLINE]
Free PMC Article

Conflict of interest statement

Dr. Terry, Dr. Nath and Mr. Zach have no conflicts of interest. Dr. Tschirren is an employee and shareholder at VIDA Diagnostics. Dr. Bolding, Mr. Stinson, Ms. Wilson, Dr. Everett, Dr. Putcha and Dr. Soler have no conflicts of interest.

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