The patients with or without GERD symptoms presenting to gastrointestinal clinic of Maharaj Nakorn Chiangmai Hospital from November 2009 to November 2010 were invited to participate in this study. All patients completed 2 validated questionnaires (RDQ: reflux diagnostic questionnaire and HRQL: Health-related quality-of-life GERD questionnaire) after giving written informed consent. Patients were enrolled if they were 18 to 80 years of age and had ability to provide written informed consent.