Amarasiri LD, Pathmeswaran A, De Silva AP, Dassanayake AS, Ranasinha CD, De Silva J. Comparison of a composite symptom score assessing both symptom frequency and severity with a score that assesses frequency alone: a preliminary study to develop a practical symptom score to detect gastro-oesophageal reflux disease in a resource-poor setting. Eur J Gastroenterol Hepatol. 2010; 22: 662-8, doi: 10.1097/MEG.0b013e32832cfe12.