Clinical Research Directory

Inclusion Criteria: * Age 18 to 80 years. * Phase 1: Participants from respiratory and critical care medicine outpatient clinics, physical examination centers, and community health centers; conscious, with basic communication and comprehension ability, able to cooperate with questionnaires and IOS/spirometry examinations; willing to sign written informed consent. * Phase 2: Patients with confirmed stable COPD (meeting GOLD criteria) or asthma (meeting GINA criteria); stable disease defined as no acute exacerbation within the past 4 weeks, without the need for systemic glucocorticoids or increased routine medication; willing to sign written informed consent. Exclusion Criteria: * Phase 1: Respiratory infection within the past 4 weeks; other severe pulmonary diseases affecting lung function (e.g., active tuberculosis, extensive bronchiectasis, pulmonary fibrosis, chest wall deformity, lung cancer); severe dysfunction of heart, brain, liver, or kidney (e.g., NYHA class III-IV, severe arrhythmia, uremia) or uncontrolled malignancy; cognitive impairment or psychiatric disorders; pregnancy or lactation; contraindications to pulmonary function tests. * Phase 2: Comorbid severe respiratory diseases (e.g., bronchiectasis, pulmonary fibrosis, lung cancer, active tuberculosis); severe heart, liver, or kidney dysfunction (e.g., NYHA class III-IV, end-stage liver disease, dialysis-dependent renal disease); conditions affecting pulmonary function test accuracy (e.g., chest wall deformity, pneumothorax, recent thoracic or abdominal surgery); severe cognitive impairment, psychiatric disorders, or communication barriers; planned relocation within 1 year or inability to complete regular follow-up; pregnancy or lactation.