i) thoracic, esophageal or gastric surgery ii) primary or secondary esophageal motility disorders iii) use of non-steroidal anti-inflammatory drugs and aspirin iv) presence of Barrett's esophagus, erosive esophagitis, peptic stricture and duodenal or gastric ulcer on upper endoscopy v) eosinophilic esophagitis vi) underlying psychiatric illness vii) pregnancy in women viii) refusal to participate.