Efficacy of Proton Pump Inhibitor for Chronic Cough Caused by Gastroesophageal Reflux; Double-blind, Placebo-controlled, Randomized Clinical Trial

Inclusion Criteria: ages of 18 and 70 years had chronic cough of \>8 weeks in duration Exclusion Criteria: 1\. abnormal chest X ray, PNS view 2. previous surgical or endoscopic antireflux procedure 3. previous aerodigestive malignancy or Barrett's oesophagus 4. current smokers or ex-smok-ers (defined as those who quit smoking \<3 months prior to study enrolment or those who have quit, but have a 20 pack year smoking history) 5. Malignancy History (lung cancer, esophageal cancer etc.) 6. upper respiratory infection within 8 weeks of study enrolment 7. currently using a PPI, H2 blocker, beta-blocker, angiotensin-converting enzyme inhibitor, corticosteroid, methylxanthine, inhaled beta-agonist, anti-inflammatory agent or anticholinesterase drug at time of enrolment