The CALIBER Study Randomized Controlled Trial of LINX Versus Double-Dose Proton Pump Inhibitor Therapy for Reflux Disease

Key Inclusion Criteria: 1. Patient seeks consultation for lack of satisfactory symptom response to once daily PPIs. 2. Age≥ 21 years old. 3. Abnormal distal esophageal pH determined by total % time pH \<4 or DeMeester Score. Testing to be completed off GERD medications for at least 7 days, with the exception of antacids, which may be taken up until the morning of assessment. 4. Suitable surgical candidate (i.e. is able to undergo general anesthesia and laparoscopic surgery). 5. Patient has provided written informed consent for participation in the randomized study. Key Exclusion Criteria: 1. Currently taking double-dose PPIs (twice daily dosing). 2. Hiatal hernia \>3cm as determined by endoscopy. 3. Distal esophageal motility (average of sensors 3 and 4) is less than 35 mmHg peristaltic amplitude on wet swallows or \<70% (propulsive) peristaltic sequences. 4. Esophagitis Grade C or D (Los Angeles classification). 5. Body mass index \>35. 6. Diagnosed with an esophageal motility disorder LES. 7. Esophageal stricture or gross esophageal anatomic abnormalities 8. History of/or known Barrett's esophagus. 9. Suspected or known allergies to titanium, stainless steel, nickel or ferrous materials.