Relationship between lung function and quantitative computed tomographic parameters of airway remodeling, air trapping, and emphysema in patients with asthma and chronic obstructive pulmonary disease: A single-center study

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• 作者：Ruth A. Hartley ; MBcHB ; MRCS^a ; Bethan L. Barker ; MBBS ; MRCP^a ; Chris Newby ; PhD^a ; Mini Pakkal ; FRCR^a ; Simonetta Baldi ; MD ; PhD^a ; Radhika Kajekar ; PhD^c ; Richard Kay ; PhD^d ; Marie Laurencin ; PhD^d ; Richard P. Marshall ; PhD ; MRCP^e ; Ana R. Sousa ; PhD^e ; Harsukh Parmar ; PhD^c ; Salman Siddiqui ; PhD ; MRCP^a ; Sumit Gupta ; PhD ; FRCR ; MRCP^a ; ^b ; ^&lowast ; ; Chris E. Brightling ; PhD ; FRCP^a ; ^&lowast ; ; ^{ceb17@le.ac.uk" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Asthma ; chronic obstructive pulmonary disease ; airway remodeling ; quantitative computed tomography ; asthma-COPD overlap syndrome ; small airway disease ; emphysema ; gas trapping
• 刊名：Journal of Allergy and Clinical Immunology
• 出版年：2016
• 出版时间：May 2016
• 年：2016
• 卷：137
• 期：5
• 页码：1413-1422.e12
• 全文大小：2047 K

文摘

There is a paucity of studies comparing asthma and chronic obstructive pulmonary disease (COPD) based on thoracic quantitative computed tomographic (QCT) parameters.

Objectives

We sought to compare QCT parameters of airway remodeling, air trapping, and emphysema between asthmatic patients and patients with COPD and explore their relationship with airflow limitation.

Methods

Asthmatic patients (n = 171), patients with COPD (n = 81), and healthy subjects (n = 49) recruited from a single center underwent QCT and clinical characterization.

Results

Proximal airway percentage wall area (%WA) was significantly increased in asthmatic patients (62.5% [SD, 2.2]) and patients with COPD (62.7% [SD, 2.3]) compared with that in healthy control subjects (60.3% [SD, 2.2], P < .001). Air trapping measured based on mean lung density expiratory/inspiratory ratio was significantly increased in patients with COPD (mean, 0.922 [SD, 0.037]) and asthmatic patients (mean, 0.852 [SD, 0.061]) compared with that in healthy subjects (mean, 0.816 [SD, 0.066], P < .001). Emphysema assessed based on lung density measured by using Hounsfield units below which 15% of the voxels lie (Perc15) was a feature of COPD only (patients with COPD: mean, −964 [SD, 19.62] vs asthmatic patients: mean, −937 [SD, 22.7] and healthy subjects: mean, −937 [SD, 17.1], P < .001). Multiple regression analyses showed that the strongest predictor of lung function impairment in asthmatic patients was %WA, whereas in the COPD and asthma subgrouped with postbronchodilator FEV₁ percent predicted value of less than 80%, it was air trapping. Factor analysis of QCT parameters in asthmatic patients and patients with COPD combined determined 3 components, with %WA, air trapping, and Perc15 values being the highest loading factors. Cluster analysis identified 3 clusters with mild, moderate, or severe lung function impairment with corresponding decreased lung density (Perc15 values) and increased air trapping.

Conclusions

In asthmatic patients and patients with COPD, lung function impairment is strongly associated with air trapping, with a contribution from proximal airway narrowing in asthmatic patients.