Association of Lung Function With Visceral Adiposity and Skeletal Muscle Mass Considering Myosteatosis.

Background: Changes in body composition, including loss of muscle mass and obesity, adversely affect lung function.

Research Question: What is the relationship between lung function, visceral adiposity, and skeletal muscle mass, considering myosteatosis measured using CT scans in middle-aged Korean adults?

Study Design And Methods: We reviewed 15,827 participants (9,237 men and 6,590 women) with a mean (SD) age of 52.5 (8.3) years who underwent comprehensive health examinations, including abdominal CT imaging and spirometry. Selected CT scans were segmented automatically to quantify total abdominal muscle area (TAMA), visceral fat area (VFA), and subcutaneous fat area. Muscle quality was assessed by categorizing TAMA into 3 regions based on CT scan density: good-quality muscle (normal attenuation muscle area [NAMA]), fatty muscle (low attenuation muscle area), and intermuscular and intramuscular fat areas. Low lung function was defined as FVC % predicted and FEV < 80% predicted. Standardized residuals for CT scan-derived measurements, adjusted for age and BMI using linear regression, were calculated and stratified into quartiles for lung function comparison. Multivariate logistic regression was used to analyze associations between low lung function and variables.

Results: NAMA was positively correlated with FVC and FEV, whereas VFA was negatively correlated with both. In men, low FVC and FEV were significantly associated with lower NAMA and higher VFA. Among women with obesity (BMI ≥ 25 kg/m), low FVC and FEV were associated significantly with higher VFA and lower NAMA (FVC only); among women without obesity, low FVC and FEV were negatively associated with NAMA.

Interpretation: Lung function was significantly associated with visceral adiposity and skeletal muscle quality, which differed according to sex and BMI. Improving lung function may require tailored management, including reducing visceral fat, enhancing skeletal muscle quality, or both, based on CT scan-body composition analysis.