Centrilobular Emphysema Is Associated with Pectoralis Muscle Reduction in Current Smokers without Airflow Limitation

Abstract

Background: Physiological and prognostic associations of centrilobular emphysema (CLE) and paraseptal emphysema (PSE) in smokers with and without chronic obstructive pulmonary disease (COPD) have been increasingly recognized, but the associations with extrapulmonary abnormalities, such as muscle wasting, osteoporosis, and cardiovascular diseases, remain unestablished.

Objectives: The aim of the study was to investigate whether CLE was associated with extrapulmonary abnormalities independent of concomitant PSE in smokers without airflow limitation.

Methods: This retrospective study consecutively enrolled current smokers without airflow limitation who underwent lung cancer screening with computed tomography and spirometry. CLE and PSE were visually identified based on the Fleischner Society classification system. Cross-sectional areas of pectoralis muscles (PM) and adjacent subcutaneous adipose tissue (SAT), bone mineral density (BMD), and coronary artery calcification (CAC) were evaluated.

Results: Of 310 current smokers without airflow limitation, 83 (26.8%) had CLE. The PSE prevalence was higher (67.5% vs. 23.3%), and PM area, SAT area, and BMD were lower in smokers with CLE than in those without (PM area (mean), 34.5 versus 38.6 cm2; SAT area (mean), 29.3 versus 36.8 cm2; BMD (mean), 158.3 versus 178.4 Hounsfield unit), while CAC presence did not differ. In multivariable models, CLE was associated with lower PM area but not with SAT area or BMD, after adjusting for PSE presence, demographics, and forced expiratory volume in 1 s.

Conclusions: The observed association between CLE and lower PM area suggests that susceptibility to skeletal muscle loss could be high in smokers with CLE even without COPD.

Keywords: Chest computed tomography; Chronic obstructive pulmonary disease; Emphysema; Muscle wasting.

Fig. 1

Prevalence of centrilobular emphysema (CLE) and paraseptal emphysema (PSE). a Evaluation of CLE. The bar graph illustrates the proportions of CLE classifications (trace: 16.1%, mild: 9.4%, moderate: 1.0%, advanced destructive: 0.3%). Moderate and advanced destructive emphysema were categorized as “severe”. b Evaluation of PSE. The proportion of PSE is depicted, divided by the presence of CLE.

Fig. 2

Comparisons of extrapulmonary CT measures between smokers with and without centrilobular emphysema (CLE). a Illustration of extrapulmonary structures, including the pectoralis muscles (PM, red), subcutaneous adipose tissue adjacent to the PM (SAT, blue), erector spinae muscles (ESM, green), and epicardial adipose tissue (EAT, magenta), coronary artery calcification (CAC, yellow), and bone marrow density (BMD, cyan) on chest CT. b PM area and SAT area were significantly lower in smokers with CLE than in those without CLE. In statistical analyses, SAT was log2-transformed. c BMD was significantly lower in smokers with CLE than in those without CLE. d The rate of CAC did not differ between smokers with and without CLE. e Height-adjusted cross-sectional areas of PM, SAT, ESM, and EAT (PM index, SAT index, ESM index, and EAT index) were also compared between smokers with and without CLE. In statistical analyses, SAT index was log2-transformed. * indicates p < 0.05 compared to smokers without CLE.