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.
Age：≥40
Suspected COPD：COPD-SQ≥16，and no evidence of airflow limitation after bronchodilators
Confirmed COPD：According to the diagnostic criteria in the 2021 Revised Edition of the Chinese Guidelines for the Diagnosis and Treatment of Chronic Obstructive Pulmonary Disease and the 2026 GOLD Report, a diagnosis requires the presence of symptoms (such as dyspnea, chronic cough, or sputum production), a history of exposure to risk factors (e.g., smoking, biomass fuels, occupational exposures, or air pollution), evidence of persistent airflow limitation (post-bronchodilator FEV1/FVC < 0.70), and the exclusion of alternative diagnoses.
Exclude acute exacerbation within the last month Asthma group：
• Contraindications for oscillometry testing and spirometry testing: Oscillometry testing: Severe and intolerable dyspnea, acute exacerbation of respiratory infection, uncontrolled epilepsy, oral or facial diseases or deformities preventing proper latching, tympanic membrane perforation, need for continuous oxygen therapy, indwelling gastric tube, tracheotomy with inability to close the tube, currently undergoing artificial ventilation and unable to temporarily stop the procedure; Spirometry testing: Recent severe cardiovascular disease, epileptic seizures, uncontrolled hypertension, aortic aneurysm, severe hyperthyroidism, heart rate >120 bpm, tympanic membrane perforation, other respiratory infectious diseases, etc.;
Other respiratory diseases that affect lung function results： such as lung cancer, pneumonia, active pulmonary tuberculosis, pulmonary embolism, etc.; Recent surgical history that affects lung function results, including open-chest surgery, pleural effusion surgery, etc.;
Poor cooperation during basic lung function tests, failing to meet quality control requirements;
Breastfeeding women;
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Trial groupsSee each trial group below.