The added diagnostic value of postreflux swallow-induced peristaltic wave index and nocturnal baseline impedance in refractory reflux disease studied with on-therapy impedance-pH monitoring

Background: On-therapy impedance-pH monitoring in proton pump inhibitor (PPI)-refractory gastroesophageal reflux disease (GERD) yielded conflicting results. We aimed to assess the diagnostic value of postreflux swallow-induced peristaltic wave (PSPW) index and mean nocturnal baseline impedance (MNBI) in PPI-refractory heartburn. Methods: On-therapy impedance-pH tracings from 189 consecutive patients with PPI-refractory heartburn were blindly reviewed. Patients were subdivided into refractory reflux esophagitis (RRE), healed reflux esophagitis (HRE), non-erosive reflux disease (NERD), and functional heartburn (FH) according to endoscopic and conventional impedance-pH findings. The diagnostic accuracy of PSPW index and MNBI in separating NERD from FH was assessed with receiver-operating-characteristic (ROC) analysis. Objectively documented persistent reflux remission at 3-year follow-up in 53 patients who underwent laparoscopic fundoplication served to evaluate PSPW index and MNBI as independent predictors of PPI-refractory GERD confirmed by positive surgical outcome. Key Results: Median PSPW index and MNBI values were significantly lower in 39 RRE (16%; 1145Ω) than in 41 HRE (25%; 1741Ω) and in 68 NERD (29%; 2374Ω) patients, and in all three GERD subgroups compared to 41 FH cases (67%; 3488Ω) (P