Tu1105 Gastric Acid Output Suppression in Response to Proton Pump Inhibitor Therapy in Symptomatic Versus Asymptomatic GERD Patients: Results of a Prospective Study Measuring Control and Meal-Stimulated Gastric Acid Secretion

Abstract

Background: Gastro-esophageal reflux disease (GERD) is a common acid-related disorder affecting 10-20% of people. GERD is often under-investigated and over-treated, especially in refractory cases. Symptoms are used to guide management despite data showing many acid reflux events are asymptomatic, and many symptomatic events are unrelated to acid reflux. Proton pump inhibitors (PPIs) effectively treat GERD, but are often over-prescribed as non-invasive, accurate methods to measure gastric acid output (GAO) and guide PPI therapy are lacking. Such data might enhance management of patients who remain symptomatic despite appropriate PPI therapy. Recently, a new method for measuring meal-stimulated GAO using a wireless pH-sensing capsule, SmartPill (SP), was validated (Weinstein et al. Aliment Pharmacol Ther 2013). Aim: To evaluate the control and stimulated GAO of GERD patients who are symptomatic (SX) vs. asymptomatic (ASX) on PPI therapy, using traditional aspiration methods and SP, respectively. Methods: A prospective, single center study of symptoms and GAO response to PPI therapy was conducted in non-erosive GERD patients with typical GERD symptoms. GERD symptoms, duration (months) and PPI use were historically recorded. Fasting serum gastrin (pg/mL) was determined. Patients withGI surgery, motility disorders, or H. pylori infection were excluded. Control acid output (CAO; mEq/ hr) was determined by titration of gastric secretions collected by nasogastric tube or EGD just prior to the next PPI dose. Fasting patients ingested a SP, followed by Ensure Plus (240 ml) (EP) diluted to either 1⁄2 or 1⁄4 strength. Meal stimulated acid output, (SP GAO (mEq/ hr)) was calculated from the time to acidify the EP meal from pH 5 to 2. Gastric emptying time (GET; minutes) was measured by SP. Results: Twenty four patients taking PPIs were enrolled; 16 had SX GERD. Mean age was similar for SX vs ASX (44.6 vs 46.1, p=0.75). SX and ASX groups did not differ in mean values for GERD duration (71.4 vs 111.4, p= 0.40), fasting gastrin (149.9 vs 157.8, p=0.90), or GET (135.3 vs 118.8, p=0.63). A nonsignificant trend toward a higher mean PPI dose was seen in SX patients (1.31 vs 1.25 X the standard dose of PPI, p=0.86). Mean CAO (2.31 vs 1.16, p=0.40) and SP GAO (28.2 vs 44.6, p=0.2) were similar in SX and ASX GERD patients. Compared to normal untreated volunteers, SP GAO was significantly lower in both SX (53 vs 28.3, p=0.0004) and ASX (53 vs 30, p=0.0095) groups. Conclusions: SX and ASX GERD patients on PPI therapy have similar CAO and SP GAO, which are significantly lower than untreated volunteers. This suggests less acid suppression is required to relieve symptoms in a subset of GERD patients, who may be less sensitive to acid reflux. Therefore, higher PPI doses may be needed to further suppress acid and relieve symptoms in unresponsive patients.