Intramuscular and Intermuscular Abdominal Fat Infiltration in COPD: A Propensity Score Matched Study

PURPOSE: Low-attenuation muscle area (LAMA) and normal-attenuation muscle area (NAMA) indicate lipid-rich and lipid-poor skeletal muscle areas, respectively. Additionally, intermuscular adipose tissue (IMAT) indicates localized fat between muscle groups. In this study, we aimed to evaluate the intramuscular and intermuscular fat infiltration in individuals with chronic obstructive pulmonary disease (COPD) by performing quantitative assessment of the LAMA, NAMA, and IMAT observed on abdominopelvic computed tomography (APCT) images. PATIENTS AND METHODS: We performed a cross-sectional study using data of subjects who underwent a general health examination with APCT at Ulsan University Hospital between March 2014 and June 2019. We classified the subjects into control and COPD groups based on age, smoking history, and pulmonary function results. We compared the attenuation and body mass index adjusted area of intra-abdominal components between the two groups using propensity score matching. We also evaluated these outcomes in COPD subgroups (mild and moderate stage subjects). RESULTS: Overall, 6,965 subjects were initially enrolled, and 250 pairs of control and COPD subjects were selected after propensity score matching. The NAMA attenuation (unstandardized β=−1.168, P<0.001) was lower, and the IMAT (unstandardized β=0.042, P=0.006) and LAMA (unstandardized β=0.120, P<0.001) indexes were greater in the COPD group than in the control group. In subgroup analysis, those with mild and moderate COPD also had high IMAT (unstandardized β=0.037, P=0.009 and unstandardized β=0.045, P<0.001) and LAMA (unstandardized β=0.089, P=0.002 and unstandardized β=0.147, P<0.001) indexes compared to the control subjects. However, the NAMA attenuation (unstandardized β=−1.075, P<0.001) and NAMA index (unstandardized β=−0.133, P=0.015) were significantly lower in moderate COPD subjects only. CONCLUSION: Our study showed that intramuscular and intermuscular abdominal fat infiltration could be present in subjects with mild COPD, and it might be exacerbated in those with moderate COPD.