Biomarker of Acute Exacerbation of COPD

For stable COPD:

Inclusion criteria

• Over 40 years old.
• in line with the diagnostic criteria in GOLD 2018.
• with the ability to sign informed consent.
• can be followed up according to the study protocol.

Exclusion criteria

• with other pulmonary diseases (such as lung cancer, sarcoidosis, tuberculosis, pulmonary fibrosis, cystic fibrosis) and severe α1-antitrypsin deficiency.
• with other inflammatory diseases (such as rheumatoid arthritis and inflammatory bowel disease, etc.).
• a history of pulmonary surgery, or a diagnosis of malignant tumor recently.
• a history of blood transfusion in 4 weeks.
• participating in a double-blind drug clinical trial.
• unable to walk.
• using oral or intravenous steroid therapy.
• with acute exacerbation in 4 weeks.

For AECOPD:

Inclusion criteria

Patients who were over 40 years old were eligible for inclusion if they had a diagnosis of COPD in their primary care clinical record and were presenting with an acute exacerbation of respiratory symptoms.

Exclusion criteria

• Other specific diseases that may account for sudden changes in respiratory symptoms should be excluded by clinical or laboratory tests.
• The remaining exclusion criteria were consistent with the above five criteria in stable COPD.

The control group:

Inclusion criteria

Healthy people over 40 years old.

Exclusion criteria

with chronic airway diseases and other lung diseases, and heart, kidney, liver, and other important organ diseases.