Body composition in stable COPD: associations with disease severity and early sarcopenia prediction

To investigate body composition changes in patients with stable chronic obstructive pulmonary disease (COPD) and their correlation with disease severity, and to assess the value of body composition indices for early identification of concomitant sarcopenia.

Patients with stable COPD were stratified according to the comprehensive disease severity assessment method in the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines, changes in body mass index (BMI), skeletal muscle index (SMI), body fat mass index (BFMI), and fat-free mass index (FFMI) were observed across groups. Factors associated with concomitant sarcopenia in COPD were analyzed, and Receiver Operating Characteristic (ROC) curves were plotted to evaluate the predictive value of the body composition indices for early screening of concomitant sarcopenia in patients with stable COPD.

A total of 237 patients with stable COPD (including 40 with concomitant sarcopenia) and 270 healthy controls were enrolled. In the stable COPD group, BMI, SMI, and FFMI were all positively correlated with FEV₁%pred and FEV₁/FVC (all p < 0.05), with correlation coefficients ranging from 0.142 to 0.194, and negatively correlated with modified Medical Research Council (mMRC) dyspnea score, COPD Assessment Test (CAT) score, and number of acute exacerbations in the past 1 year (r = -0.405, -0.405, -0.174, p < 0.01; r = -0.336, -0.298, -0.208, p < 0.01). SMI and FEV₁%pred were independent predictors of concomitant sarcopenia (OR = 0.011, 0.868; p < 0.05). The combined SMI and FEV₁%pred showed superior diagnostic performance (AUC = 0.990, 95%CI: 0.981-0.998).

Body composition alterations occur during the stable phase of COPD, especially a reduction in skeletal muscle mass. Changes in skeletal muscle indices in patients with stable COPD are significantly correlated with disease severity. Body composition analysis has potential clinical value for early identification of skeletal muscle impairment and disease assessment in stable COPD patients, and may be considered as a supplementary component of routine follow-up.