CHANGES IN ESOPHAGEAL PH ASSOCIATED WITH GASTROESOPHAGEAL REFLUX - ARE TRADITIONAL CRITERIA SENSITIVE FOR DETECTION OF REFLUX

Traditionally, gastro-oesophageal reflux is deemed to have occurred wh en oesophageal pH falls below 4. Other 'non-traditional' pH changes th at do not fall below pH 4, that fall below 4 for only brief intervals, or that occur when basal pH is less than 4 are usually disregarded. T he aim of this study was to determine whether these non-traditional pH changes represent gastro-oesophageal reflux or are artefactual. The 3 -h postprandial combined oesophageal pH and manometric records of 22 p atients referred for investigation of suspected gastro-oesophageal ref lux were reviewed. All pH falls of greater-than-or-equal-to 0.5 pH uni ts were analysed for manometric evidence of reflux that was classified as definite, probable, or possible. In total, 196 traditional and 223 non-traditional pH events were scored and analysed. The majority of t raditional (80%) and non-traditional (60%) events were associated with definite manometric evidence of reflux, although a greater proportion of non-traditional events were associated with only probable evidence of reflux (33%) compared with traditional events (18%). The proportio ns of possible reflux were similar in the two groups. Limiting pH even ts to only those satisfying traditional criteria excluded an additiona l 32% with definite manometric evidence of reflux and 49% with definit e or probable evidence of reflux. Most pH falls that remained above 4 or fell across 4 for <15 sec occurred in the 1st h postprandially, com pared with traditional pH events, which occurred equally throughout th e 3-h period. We conclude that traditional criteria for scoring pH epi sodes substantially underestimate the number of reflux episodes.