To comprehensively evaluate the pulmonary rehabilitation (PR) outcomes of patients with chronic respiratory disease (CRD), and to screen biomarkers for predicting different PR outcomes of patients with CRD using metabolomics methods, and to build a prediction model.

Inclusion Criteria:

• For COPD

  1. Meets the Global initiative for chronic obstructive lung disease (GOLD) 2022 definition of stable COPD;
  2. Age 30-75 years;
  3. Lung CT images only showed chronic bronchitis and emphysema;
  4. Agree to participate in the study and is able to cooperate with exhaled breath condensate collection.

• For bronchiectasis

  1. Lung CT showed bronchiectasis;
  2. Age 18-75 years;
  3. Spirometry suggests obstructive ventilatory dysfunction: forced expiratory volume in one second (FEV1) is less than 70% of forced vital capacity (FVC) post bronchodilator inhalation.

Exclusion Criteria:

1. Asthma or other respiratory diseases
2. History of pulmonary surgery
3. α1 antitrypsin deficiency
4. Autoimmune diseases
5. Patients with acute myocardial infarction, chronic heart failure, severe cerebral infarction or cerebral hemorrhage
6. A history of malignant disease now or within 2 years
7. History of acute exacerbation or change of medication in the past 4 weeks
8. A history of blood transfusion within the last 4 weeks
9. Drugs or alcohol abuse
10. Breastfeeding or pregnant women
11. Unable to cooperate with pulmonary rehabilitation for various reasons

Outpatients in respiratory and critical care medicine department of Peking University Third Hospital