Cohort Study of Airway Microecology and the Pathogenesis and Evolution of Chronic Obstructive Pulmonary Disease

This study will last for 5 years (2021.2.25-2025.12.31). 210 patients (70 cases in each group) will be enrolled in this study. Eight centers in China will participate in the study. The patients will be treated with bronchoscopy alveolar lavage, and 60 ml of bronchoalveolar lavage fluid will be collected for the next-generation sequencing of airway microorganisms. The patients will be followed up for 4 years to observe the changes of lung function, Fractional exhaled nitric oxide (FENO) and clinical symptoms.