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PTH-132 Analysis of gastric ph by endofaster in combination with standard clinical parameters can predict response to ppi in patients with gastro-oesophageal reflux disease
  1. J Hartley1,
  2. A Rattan2,
  3. B Alias1,
  4. T Nuchcheddy-Grant1,
  5. L Wernisch3,
  6. A Hobson4,
  7. M Di Pietro
  1. 1MRC CANCER UNIT – University of Cambridge
  2. 2Gastroenterology, Cambridge University Hospital
  3. 3MRC Biostatistics Unit, University of Cambridge, Cambridge
  4. 4The Functional Gut Clinic, London, UK


Introduction Up to 30% of patients with gastro-oesophageal acid reflux treated with acid suppressing drugs have pathological oesophageal acid exposure and symptoms on their own are poor predictors. Endofaster allows real time pH analysis of gastric juice during endoscopy. We hypothesised that in patients on proton pump inhibitors (PPI) or H2 receptor antagonists (H2RA) the presence of an acidic gastric pH at the time of the endoscopy, alone or in combination with other clinical factors, could predict response to medical therapy.

Method This was a prospective cohort study. We recruited patients referred for OGD and on daily medical therapy with PPI or H2RA, with stable dose in the last 2 weeks. Patients who missed the last dose of medication prior to the OGD were excluded. Symptoms were assessed by validated questionnaire (GERD-Q). Single time-point reading of gastric pH was taken by Endofaster at OGD. Immediately after the endoscopy, patients received an ambulatory pH-impedance monitoring to assess 24 hour gastric and oesophageal acid exposure. Logistic regression was used to assess for relationships between 24 hour pH readings and other clinical parameters including gastric pH by Endofaster, endoscopic findings, dose of medications and symptom pattern.

Results Of the 84 patients recruited 22 were excluded due to insufficient gastric juice at the time of the OGD, failure of pH-impedance or voluntary suspension of the PPI/H2RA. 77% of the patients were on PPI alone and the others either on H2RA or the combination of the two. In keeping with the previous evidence, 30% of the patients had pathological levels of oesophageal acid exposure. Single time-point gastric pH by Endofaster correlated significantly with 24 hour gastric pH (p=0.01), however, it did not correlate significantly with 24 hour oesophageal acid exposure (p=0.18). The logistic regression analysis identified 5 clinico-endoscopic factors that combined were predictive of 24 hour oesophageal pH (p=0.034). Endofaster pH, severity of heartburn and frequent acid taste positively correlated with oesophageal acid exposure, while high dose of PPI and frequency of heartburn were negative predictors.

Conclusion These results indicate that in patients on acid suppressing therapy single time-point gastric pH in combination with other clinical factors can predict 24 hour acid exposure and aid clinical management.

Disclosure of Interest None Declared

  • endofaster
  • Gastro-oesophageal reflux disease
  • pH-impedance
  • Proton pump inhibitors

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