369 Impact of Selective Criteria for Esophageal Acid Exposure in Patient on PPI Therapy

Abstract

INTRODUCTION: The Lyon consensus defined diagnostic guidelines and criteria for GERD and NERD. pH impedance testing is a mainstay of diagnostic confirmation of GERD, but use of PPI prior to pH impedance testing can confound results if esophageal acid exposure (EAE) interpretation is not adjusted for this variable. We sought to demonstrate the necessity of selective EAE criteria in those on PPIs to improve diagnostic accuracy of pH impedance testing. METHODS: 117 consecutive adult patients referred for medication (H2RA, PPI) refractory GERD-symptoms were included. Patients completed RSI, GERDQ, and then 24 hour pH impedance. Patients were divided into 2 groups, those on PPI (n = 82) and those off PPI (n = 35). EAE was interpreted first with uniform off therapy criteria; then the PPI group was re-interpreted with selective on therapy cutoffs. On therapy cutoffs for normal acid exposure were < 1.5% upright and < 0.5% recumbent; off therapy cutoffs were < 6.3% upright and < 1.2% recumbent. RESULTS: In group 1 (on PPI), when on-therapy criteria were applied, 37% (31/82) of patients had abnormal EAE, while with the uniform criteria 25.6% (21/82) had abnormal EAE. In group 2 (off PPI), 13/35 (37%) had abnormal pH-impedance results. There was a significant difference between the two groups (P = 0.02). Those on PPI did not have significantly improved abnormal upright EAE (23% vs 11%, P = 0.44), recumbent EAE (16% vs 11%, P = 0.53). Those on PPI therapy had a greater number of abnormal GERDQ (56.1% vs 45.7%, P = 0.30) and RSI (74.4% vs 60.0%, P = 0.12). CONCLUSION: Application of selective criteria for EAE interpretation improves diagnostic accuracy of pH impedance testing, though those with abnormal EAE are not significantly more likely to have positive GERDQ or RSI results. PPI use does not decrease individual abnormal upright or recumbent esophageal acid exposure when selective criteria for PPI use are applied.