There are difficulties in recruiting patients

Cough is a common symptom that leads patients worldwide to seek medical attention. Subacute cough refers to a cough of 3-8-week duration, and is typically refractory to standard anti-tussive therapy, and a tendency to spontaneous healing was common. Few clinical trials have evaluated therapeutic options for subacute cough. Airway inflammation is an important feature of most of subacute cough, Cysteinyl leukotrienes and FeNO correlates with airway inflammation. Subacute cough often represents a prolonged post-viral response. Cysteinyl leukotrienes increase in virus infection. Airway inflammation induce epithelial cells produce iNOS(inducible nitric oxide synthase,iNOS), and FeNO increase in theory. Montelukast is a cysteinyl leukotriene type 1 receptor antagonist that is reported to improve cough16 and reduces FENO and prevents increases in FENO during reduction of inhaled corticosteroid dose, But A meta-analysis of the effectiveness of LTRA( leukotriene receptor antagonist,LTRA)in treating children with prolonged non-specific cough concluded that, with the lack of evidence, the routine use of LTRA in treating children with non-specific cough cannot be recommended. A randomised, placebo-controlled trial showed montelukast is not an effective treatment for postinfectious cough. Non-specialists or general practitioners of Japan prescribe LTRA very often, which increase. The aim is to research whether FeNO can be used as a biomarker to direct montelukast treatment and optimize treatment regimen of sub-acute cough.

This project is a prospective, open label, randomized and controlled trial. All subacute cough patients that met the inclusion/exclusion criteria were recruited after signing the consent form. Patients were randomized into biomarker treatment armand standard treatment arm.

Patients in biomarker treatment arm and FENO≥25ppb were given Montelukast Sodium Tablets (p.o., 10mg, q.d.) . Patients in biomarker reatment arm and FENO<25ppb were given placebo (p.o., 10mg, qd). Patients in standard treatment arm and FENO≥25ppb were given placebo (p.o., 10mg, qd). Patients in standard treatment arm and FENO<25ppb were given Montelukast Sodium Tablets (p.o., 10mg, q.d.) .All treatment regimens lasted for 10 days and no other antitussive/decongestant or bronchodilators are given to any patients.

Examine results of all patients from all arms were recorded before and after the 10 day treatment. The examine recorded are FENO levels, cough symptom assessment, cough visual assessment, Leicester cough questionnaire, total white blood cell count, neutrophil blood percentage, eosinophil blood percentage. Patient cough free days after treatment and Montelukast Sodium Tablets . Follow up was carried out at the 8th week after first record of symptom and 2 month after treatment.

Inclusion Criteria:

• Cough is the main or only clinical symptom and was persistent for 3-8 weeks Chest X-ray reveals no noticeable pathological changes
• more than 18 year old, regardless of gender and ethical background
• Not taking angiotensin-converting enzyme inhibitor
• Patients must join the programme voluntarily and are able to attend examination and follow-up sessions

Exclusion Criteria:

• Patients diagnosed with allergic rhinitis, chronic nasosinusitis or bacterial respiratory tract infections
• Patients diagnosed with severe reportorial disease of other severe systemic disease
• Patients who are allergic to any drugs to be tested
• Patients who are non-cooperative during examination sessions or other steps of the trial
• Patients who are not able to or refuse to sign consent