To investigate and compare the value of FeNO, blood Eos, serum TIgE in predicting the airway eosinophilic inflammationin chronic cough, asthma and COPD.

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.

Inclusion Criteria:

• Candidates voluntarily participate in and abide by the relevant regulations of the study, can cooperate with corresponding inspections, follow the follow-up plan, and voluntarily sign written informed consent.

• Patients with chronic cough

  1. Coughing lasting ≥ 8 weeks,
  2. There is no obvious abnormality in the chest X-ray
  3. No clear history of upper respiratory tract infection in the past 4 weeks,
  4. Newly diagnosed or untreated in the last 4 weeks
  5. Non-smokers.

• Patients with Asthma

  1. For newly diagnosed and previously diagnosed asthma patients, the diagnosis criteria for asthma:
  2. Including various disease severity (mild, moderate, severe), various disease states (chronic duration, acute exacerbation period).
  3. Non-smokers.

• Patients with COPD 1) Including patients in stable phase and acute exacerbation phase.

Exclusion Criteria:

• Diagnose patients with ACO;
• Those who cannot cooperate with the completion of research-related test, follow-ups and other reasons cannot cooperate with the progress of the research;
• Combined with serious diseases of other systems (such as cardiovascular, metabolic, immune, neurological, etc.). With other diseases of the lung, including bronchiectasis.

Chronic cough, asthma, and COPD patients