This study is a randomized crossover study. COPD patients aged 40 years or older with stable disease are included. Each patient receives four weeks of treatment with either BGF or FUV followed by a one-week washout period, and then four weeks of treatment with the other drug. Respiratory symptoms are assessed using modified Medical Research Council (mMRC) dyspnea scale and COPD Assessment Test (CAT). Pulmonary function is assessed by spirometry with bronchodilator testing, and adverse events were recorded. Spirometry data, including forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and forced expiratory flow at 25-75% of FVC (FEF25-75) are also collected. Impulse oscillometry (IOS) is also performed, with results reported as R5, R20, R5-R20, X5, Fres, and Ax.
