Cough is the most common complaint in the respiratory department, while asthma and chronic obstructive pulmonary disease(COPD) are two major respiratory disease that seriously endanger human health. The common test to identify the cause and evaluate the therapeutic effect such as induced sputum, pulmonary ventilation function test, bronchial provocation test, etc. are time-consuming and laborious. There is an urgent need for an easily detectable index in the clinic to quickly identify airway eosinophilic inflammation in chronic cough, asthma and COPD, which will provide important guidance for clinical treatment.~As a new marker of airway inflammation, exhaled nitric oxide(FeNO) can reflect eosinophilic airway inflammation. Mean while, FeNO has the advantages of non-invasive, simple operation, time-saving, labor-saving, and good reproducibility, which is suitable for clinical application.~This prospective, multi-center study aims to explore the value of FeNO in predicting airway eosinophilic inflammation and compare it with blood Eos and TLgE in patients with chronic cough, asthma and COPD.
To investigate and compare the value of FeNO, blood Eos, serum TIgE in predicting the airway eosinophilic inflammationin chronic cough, asthma and COPD.