Quantitative CT: Associations between Emphysema, Airway Wall Thickness and Body Composition in COPD

Erica P A Rutten,Amund Gulsvik,Sreekumar G Pillai,Thomas B Grydeland,Asger Dirksen,Scott Wagers,Harvey O Coxson,Per S Bakke,Emiel F M Wouters

doi:10.1155/2011/419328

Abstract

The objective of the present study was to determine the association between CT phenotypes—emphysema by low attenuation area and bronchitis by airway wall thickness—and body composition parameters in a large cohort of subjects with and without COPD. In 452 COPD subjects and 459 subjects without COPD, CT scans were performed to determine emphysema (%LAA), airway wall thickness (AWT-Pi10), and lung mass. Muscle wasting based on FFMI was assessed by bioelectrical impedance. In both the men and women with COPD, FFMI was negatively associated with %LAA. FMI was positively associated with AWT-Pi10 in both subjects with and without COPD. Among the subjects with muscle wasting, the percentage emphysema was high, but the predictive value was moderate. In conclusion, the present study strengthens the hypothesis that the subgroup of COPD cases with muscle wasting have emphysema. Airway wall thickness is positively associated with fat mass index in both subjects with and without COPD.

Highlights

Chronic obstructive pulmonary disease (COPD) is, besides a respiratory disorder, recognized as a systemic disease with extrapulmonary manifestations
Only in the subjects with COPD, lung mass was significantly correlated with %LAA (r = −0.26, P < .01), and the correlation remained after correction for FFMI (r = −0.23, P < .01)
The results of the present study reveal that fat free mass index decreases as the level of emphysema increases in both men and women with COPD

Summary

Introduction

Chronic obstructive pulmonary disease (COPD) is, besides a respiratory disorder, recognized as a systemic disease with extrapulmonary manifestations. It has recently been shown that the extent of emphysema measured by percentage of low attenuation areas (%LAA) is inversely associated with body mass index (BMI: body weight/height2) [2] Another recent paper confirmed these data by showing an inverse correlation between the %LAA and both fat free-mass index (FFMI, a marker for skeletal muscle mass: fat free mass (FFM)/height2) and fat mass index (FMI, fat mass (FM)/height2) in subjects with COPD [3]. Both studies [2, 3] were restricted to heavy smoking men

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