PFT (FEV1%, FEV1/FVC), 6MWD, clinical symptom score, QoL score(“Zhong Shan COPD questionnaire”), ABGA (PaO2, PaCO2), number of AECOPD, immune cytokines (TNF-α, IL-8, IL-6). Here, CXCL8 is linked to chronic obstructive pulmonary disease.