A Study to Evaluate the Diagnostic Performance of Portable Oscillometry Across Chronic Respiratory Diseases

This is a prospective, multicenter, observational cohort study enrolling approximately 4,000 subjects across about 50 centers, including patients with COPD (confirmed and suspected), asthma (confirmed and suspected), bronchiectasis, interstitial lung disease (ILD), upper airway obstruction (UAO), and healthy controls. Participants will undergo standardized clinical assessments, cough search, FENO, ETCO2, impulse oscillometry, spirometry, and/or bronchodilator test, and/or bronchoprovocation test, and/or diffusion capacity test at a single baseline visit, with no investigational intervention or treatment assignment. The primary objective is to evaluate the diagnostic performance of portable impulse oscillometry in Chronic respiratory diseases and to develop an artificial intelligence diagnostic model for COPD based on oscillometry. The study duration per subject is limited to the screening/baseline visit, with no follow-up visits planned.