Chronic obstructive pulmonary disease (COPD) is the most common chronic tract disease and the third leading cause of death worldwide. The treatment effect of COPD is poor, and the disease is progressive, resulting in a serious disease burden. The key reason is that early recognition is difficult and the early pathophysiological mechanism is unclear, which leads to the difficulty of early intervention.PRISm is likely to be the precursor stage of COPD, which may provide an important research object for the study of pathophysiological characteristics, inflammation and immunomodulatory mechanisms of early COPD, and may also become a new entry point for early intervention of COPD. This study attempts to establish a PRISm prospective cohort，and collects blood, EBC and urine for analysis of inflammatory factors, metabolomics, proteomics and microbiome, and performs chest HRCT to obtain imaging indicators, and conducts 3-year dynamic follow-up observation to study the evolution characteristics of pulmonary function and the incidence of COPD in the PRISm cohort. To compare the differences in imaging, inflammatory factors, metabolomics, proteomics and microbiome among the three PRISm groups, and establish a risk prediction model for progression to COPD through PRISm. It lays a foundation for understanding the characteristics of COPD at an earlier stage and exploring new early warning indicators.

Inclusion Criteria:

• 1) Age range from 20 to 75 years old, regardless of gender; 2) Pulmonary function test: After inhaling bronchodilators, FEV1/FVC ≥ 70%, and FEV1<80% of the expected value; 3) Agree to enter this research project and sign an informed consent form 4) Able to comply with research protocols.

Exclusion Criteria:

• 1) Confirmed chronic obstructive pulmonary disease, bronchial asthma, bronchiectasis, interstitial lung disease, occupational lung disease, tuberculosis, pulmonary vascular disease, central airway stenosis and other confirmed respiratory diseases.

  2) Have undergone lobectomy and/or lung transplantation; 3) complicated with serious underlying diseases (including serious mental illness, mental retardation, neurological disease, malignant tumor, chronic liver disease, heart failure, autoimmune disease, chronic kidney disease); 4) accompanied by severe pleural disease and/or lesions of the sternum or ribs; 5) Have active tuberculosis or are receiving anti-tuberculosis treatment; 6) Pregnancy or lactation; 7) Can not be followed up for a long time or poor compliance;

The subjects are 1430 PRISm people from the PIFCOPD cohort in our center and 600 newly enrolled PRISm people in this study, totaling approximately 2000 PRISm people.