Time esophageal pH &lt; 4 overestimates the prevalence of pathologic esophageal reflux in subjects with gastroesophageal reflux disease treated with proton pump inhibitors

Lauren B Gerson,Philip B Miner,Peyman Sahbaie,Winston Young,Sheldon Sloan,Jerry D Gardner,George Triadafilopoulos,Malcolm Robinson

doi:10.1186/1471-230x-8-15

Abstract

BackgroundA Stanford University study reported that in asymptomatic GERD patients who were being treated with a proton pump inhibitor (PPI), 50% had pathologic esophageal acid exposure.AimWe considered the possibility that the high prevalence of pathologic esophageal reflux might simply have resulted from calculating acidity as time pH < 4.MethodsWe calculated integrated acidity and time pH < 4 from the 49 recordings of 24-hour gastric and esophageal pH from the Stanford study as well as from another study of 57 GERD subjects, 26 of whom were treated for 8 days with 20 mg omeprazole or 20 mg rabeprazole in a 2-way crossover fashion.ResultsThe prevalence of pathologic 24-hour esophageal reflux in both studies was significantly higher when measured as time pH < 4 than when measured as integrated acidity. This difference was entirely attributable to a difference between the two measures during the nocturnal period. Nocturnal gastric acid breakthrough was not a useful predictor of pathologic nocturnal esophageal reflux.ConclusionIn GERD subjects treated with a PPI, measuring time esophageal pH < 4 will significantly overestimate the prevalence of pathologic esophageal acid exposure over 24 hours and during the nocturnal period.

Highlights

A Stanford University study reported that in asymptomatic GERD patients who were being treated with a proton pump inhibitor (PPI), 50% had pathologic esophageal acid exposure
We considered the possibility that the high prevalence of pathologic esophageal reflux in the Stanford study might have resulted from calculating acidity as time pH < 4
In the present analyses we used these cut-points (8.1 mmol.hr/L for integrated acidity and 4.3% for time pH < 4) to compare the prevalence of pathologic esophageal reflux defined by the different measures of esophageal acidity in the index study

Summary

Introduction

A Stanford University study reported that in asymptomatic GERD patients who were being treated with a proton pump inhibitor (PPI), 50% had pathologic esophageal acid exposure. In 2004, a group from Stanford University reported that in asymptomatic GERD patients who were being treated with a PPI, 50% had pathologic esophageal acid exposure [1]. The authors of this paper stated that they were surprised by this high prevalence of pathologic esophageal acid exposure and an accompanying editorial pointed out that the findings were difficult to reconcile with a large body of evidence supporting the outstanding therapeutic efficacy of PPIs in GERD [2]. We considered the possibility that the high prevalence of pathologic esophageal reflux in the Stanford study might have resulted from calculating acidity as time pH < 4. The present paper reports the results of these analyses as well as analyses of results from another study of GERD subjects that were conducted to test hypotheses that were generated from the Stanford data

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