Differential Impact of Low Fat-Free Mass on Prognosis of Patients With Chronic Obstructive Pulmonary Disease (COPD)

Chronic obstructive pulmonary disease (COPD) is a heterogeneous lung condition characterized by chronic respiratory symptoms (dyspnea, cough, sputum production and \ or exacerbations) due to abnormalities of the airways (bronchitis, bronchiolitis) and\ or alveoli (emphysema) that cause persistent, often progressive, airflow obstruction.

COPD is characterized by a progressive and irreversible decline in lung function. In addition, COPD is recognized as a systemic disease with significant extra pulmonary effects.

Loss of skeletal muscle mass is a well described and clinically relevant systemic consequence of COPD. Across the disease severity spectrum of COPD, the prevalence of abnormally low muscle mass (i.e. sarcopenia or cachexia) is estimated to be ∼23%.

The etiology of muscle dysfunction in COPD is complex and multifactorial. Proposed pathophysiological mechanisms include 1) disease-related factors such as systemic inflammation; 2) ageing; and 3) behavior modification, particularly less time spent physically active and more time spent sedentary.

The rate of age-related decline in skeletal muscle function is accelerated in people with COPD compared to that of otherwise healthy adults (Limpawattana et al., 2018). Additionally, loss of muscle function begins early in the disease course, with ostensible muscle dysfunction observed in people with mild COPD.