Association Between CT-based Mucus Plug Score and Bendopnea in Patients with Chronic Obstructive Pulmonary Disease

Association Between CT-based Mucus Plug Score and Bendopnea in Patients with Chronic Obstructive Pulmonary Disease Author:　Toshitaka Shomura1), Yosuke Wada1), Zhang Ziele1), Yuika Nakamura2), Yusuke Suzuki1), Norihiko Goto1), Yoshiaki Kitaguchi1), Atsuhito Usiki1), Masanori Yasuo2), Masayuki Hanaoka1) Institute: 1) The first department of Internal Medicine, Shinshu University School of Medicine, Matsumoto, Nagano, Japan 2)Departments of Clinical Laboratory Sciences, Shinshu University School of Health Sciences, Matsumoto, Nagano, Japan. Background and Aims Bendopnea, defined as dyspnea while bending forward, has been primarily studied in heart failure, but its significance in chronic obstructive pulmonary disease (COPD) remains unclear. Airway mucus plugging, quantified by computed tomography (CT), has emerged as an important imaging marker linked to airflow limitation and symptom burden in COPD. We hypothesized that a higher CT-based mucus plug score is independently associated with the presence of bendopnea in COPD patients. Methods We conducted a retrospective cross-sectional study of 133 patients with COPD. Bendopnea was assessed clinically and was present in 27 patients (20.3%). Mucus plug score was quantified from chest CT images. Patient demographics, pulmonary function tests, low attenuation volume percentage (LAV%), hemodynamic parameters (BNP, TRPG, EF), and symptom scores were compared between groups. Multivariate logistic regression analyses were performed to evaluate the independent association of mucus plug score with bendopnea, adjusting for %FEV1 and LAV%. Results Bendopnea-positive group exhibited significantly higher mucus plug scores compared to the Bendopnea-negative group (median 2.0 [IQR 1.0–4.0] vs. 0.0 [0.0–1.0], p < 0.001). The Bendopnea-positive group also demonstrated more severe airflow limitation (%FEV1: 51.3% vs. 73.7%, p < 0.001), greater emphysema (LAV%: 12.2% vs. 3.6%, p = 0.008). In contrast, hemodynamic parameters showed no significant between-group differences. In multivariate logistic regression analyses, mucus plug score remained a significant independent predictor of bendopnea across all models: adjusted for %FEV1, adjusted for LAV%, adjusted for both %FEV1 and LAV%. Bendopnea prevalence increased with rising mucus plug scores (P for trend < 0.001). Conclusions CT-based mucus plug score is significantly and independently associated with bendopnea in COPD patients, irrespective of the degree of airflow limitation, emphysema. These findings suggest that bendopnea may be a clinical clue to mucus-predominant airway disease in COPD.