Association of Airway Mucus Plugs and Physical Activity, Exercise Tolerance, Sarcopenia, and Frailty in Patients With COPD and Pre‐ COPD

BACKGROUND AND OBJECTIVE: Airway mucus plugs on computed tomography (CT) are an imaging biomarker of chronic obstructive pulmonary disease (COPD) associated with airflow limitation, respiratory symptoms, and poor prognosis. However, clinical phenotypes relevant to mucus plugs, including sarcopenia and frailty, are not fully elucidated. This study aimed to investigate the association between mucus plugs, sarcopenia, and frailty using a prospective observational COPD-enriched smoker cohort. METHODS: In this cross-sectional analysis, patients with COPD and pre-COPD were classified into no-, low-, and high-mucus groups according to mucus scores on CT. The risks of frailty and sarcopenia, and relevant clinical, functional, and imaging factors including 6-min walk distance (6MWD), physical activity, body compositions via bioelectrical impedance analysis (BIA), and intra- and extrapulmonary CT indices were compared between groups. RESULTS: Among 175 patients (142 COPD, 33 pre-COPD, and n = 106, 48, and 21 in the no-, low-, and high-mucus groups), the high-mucus group was associated with increased odds ratio for sarcopenia independent of age, sex, height, smoking, and forced expiratory volume in 1 s, or emphysema and wall area percentage (WA%). The high-mucus group demonstrated increased airtrapping and WA%, reduced total airway count, and decreased muscle and fat mass (assessed by both BIA and CT), while emphysema was not different. Furthermore, 6MWD deteriorated in the high-mucus group independent of age, sex, height, and smoking, whereas physical activity did not differ. CONCLUSION: In patients with COPD and pre-COPD, mucus plugs are associated with reduced muscle and fat mass and a heightened sarcopenia risk.