keywords DIAGNOSTIC-VALUE ENDOSCOPIC ASSESSMENT EROSIVE ESOPHAGITIS GASTROESOPHAGEAL-REFLUX DISEASE GERD GERD QUESTIONNAIRE Gastroenterology & Hepatology Life Sciences & Biomedicine NONCARDIAC CHEST-PAIN OMEPRAZOLE TEST PPI PROTON-PUMP INHIBITORS QUESTIONNAIRE REQUEST(TM) ReQuest Science & Technology UNINVESTIGATED DYSPEPSIA endoscopy pH monitor symptoms