Chronic cough of unknown causes and gastroesophageal reflux disease: the incidence and treatment response

Background : Gastroesophageal reflux disease (GERD) is a common cause of chronic cough. Nevertheless the incidence of GERD is low in Korea. We evaluated the necessity of tests for GERD as a cause of chronic cough and treatment responses to proton pump inhibitors. Methods : Patients with cough for more than three weeks were enrolled. Patients who were diagnosed as bronchial asthma, eosinophilic bronchitis, and posterior nasal drip were differentiated. Twenty four hour ambulatory esophageal pH monitoring was performed in patients with chronic cough of unknown causes or gastroesophageal reflux symptoms. Patients were diagnosed as GERD when DeMeester composite score was over 14.7 or symptom sensitivity index was over 10 percent. We prescribed proton pump inhibitors for patients diagnosed as GERD. Results : Sixty seven of 531 patients supposedly needed 24-hour ambulatory esophageal pH monitoring. 24-hour ambulatory esophageal pH monitoring was performed in 34 patients and eight patients were diagnosed as GERD. Symptoms improved in 5 patients on taking omeprazole 20-40 mg/day single or combined with prokinetic agents. Conclusions : Among patients with chronic cough, not many cases needed to take 24-hour ambulatory esophageal pH monitoring. The incidence of GERD, diagnosed by 24-hour ambulatory esophageal pH monitoring, in chronic cough of unknown causes was low. The effect of omeprazole was similar to the previous reports.