Chest CT-scan analysis of skeletal muscles in patients with alpha-1-antitrypsin deficiency

Objectives Alpha-1-antitrypsin deficiency (AATD) is a genetic disorder commonly associated with chronic obstructive pulmonary disease (COPD). Skeletal muscle atrophy is associated with higher mortality in COPD patients, but has been scarcely evaluated in AATD. This study aimed at assessing skeletal muscle parameters in AATD patients and evaluating their association with respiratory parameters. Secondary objectives included a comparison of muscle parameters with non-AATD COPD patients. Methods A monocentric cross-sectional observational study was conducted. Skeletal muscle (pectoralis, erector spinae, psoas) surfaces and densities were measured on thoracic computed tomography (CT) scans and correlated with respiratory parameters. Muscle parameters were also measured in an independent cohort of non-AATD COPD patients (COBRA). Results Fifty-three AATD patients were included. In univariate analysis, a significant correlation was observed between pectoralis surface and FEV1; between erector spinae surface and PaO2 and LAV%; and between psoas surface and PaO2. In multivariate analysis accounting for age, sex, body surface area and number of pack-years, we identified a significant correlation between pectoralis surface and FEV1. In the paired comparison, AATD patients showed significantly reduced pectoralis and erector spinae muscle surfaces compared to age- and sex-matched non-AATD COPD patients. Moreover, erector spinae density was significantly greater and psoas density was significantly lower in the AATD group. Conclusion Thoracic muscle surfaces are moderately associated with respiratory function metrics in AATD patients, and appear to be lower than in non-AATD COPD patients. These findings underscore the need for further research into a possible specific form of muscle involvement in AATD.