Cough is the most common symptom in respiratory specialist clinics of tertiary hospitals and outpatient clinics of primary health care facilities. In China, patients with chronic cough account for at least one third of all patients referred to respiratory specialist clinics. Chronic cough without significant abnormal chest radiographic findings is often misdiagnosed as chronic bronchitis or chronic pharyngitis. Misdiagnosis of cough results in unnecessary repetitive testing, such as chest radiographs or computed tomography (CT), and widespread abuse of antibiotics or antitussives with little improvement, and potential adverse effects. Chronic cough impair quality of life badly cause severe economic burden in China (1-5).