Diagnostic Utility of Impedance-pH Monitoring in Refractory Non-erosive Reflux Disease

BACKGROUND/AIMS: Approximately one-third of non-erosive reflux disease (NERD) patients are refractory to proton pump inhibitors (PPI) and face a therapeutic challenge. Therefore, it is important to differentiate between pathological and non-pathological reflux utilizing multichannel intraluminal impedance-pH (MII-pH) to analyze symptom-reflux association and diagnose true NERD versus hyper-sensitive esophagus (HE) and functional heartburn (FH). Herein, we evaluated the diagnostic yield of MII-pH in refractory NERD and sub-classified it based on quantity and quality of acid/non-acid reflux and reflux-symptom association. METHODS: Sixty symptomatic NERD patients on twice daily PPI for > 2 months were prospectively evaluated by MII-pH. Distal and proximal refluxes, bolus exposure time (BET), esophageal acid exposure time, symptom index (SI) and symptom association probability (SAP) were measured. RESULTS: Thirty-two (53%) patients had BET > 1.4% (MII-pH positive-true NERD), while 28 (47%) had BET < 1.4% (MII-pH negative NERD) where SI and SAP were negative in 15/60 (25%; categorized as FH) and SI or SAP were positive in 13/60 (22%; identified as HE). Thirty-eight (63%) patients reported significant SI or SAP parameters where > 80% of symptoms were associated with non-acid reflux. The number of distal refluxes in true NERD versus FH or HE were significantly different, but not between FH and HE. CONCLUSIONS: Approximately 60% of refractory PPI NERD patients had positive reflux-symptom association, primarily due to non-acid reflux. Nearly half of NERD patients on PPI had normal MII-pH monitoring, sub-divided further into FH and HE equally.