Usefulness of baseline impedance in patients with proton pump inhibitor-refractory nonerosive reflux disease

Background and AimApproximately more than half of patients with non-erosive reflux disease (NERD) do not respond to proton pump inhibitor (PPI) therapy. Although NERD is a heterogeneous entity, previous study showed that multichannel intraluminal impedance (MII)-pH monitoring could distinguish reflux-related disease from PPI-refractory NERD. The aim of this study was to examine the usefulness of baseline impedance in PPI-refractory NERD patients. MethodsWe used MII-pH monitoring to analyze reflux parameters, symptom index (SI), and baseline impedance in 37 PPI-refractory NERD patients on PPI. Reflux was divided into acid (nadir pH4) and non-acid (nadir pH>4). Subjects were classified as having reflux-related disease based on abnormal reflux parameters or positive SI (50%), or non-reflux-related disease, including functional heartburn, based on negative SI with normal reflux parameters. ResultsA total of 26 of the 37 subjects were diagnosed with reflux-related disease, including eight with acid-reflux type and 18 with non-acid-reflux type, and nine with functional heartburn and two with pseudohypersalivation. There were no significant differences in the clinical characteristics of the acid-reflux type, non-acid-reflux type, and functional heartburn groups. The baseline impedance value in the acid-reflux type (1245392 ) was significantly lower than that in the non-acid-reflux type (2824 +/- 1160 ) and functional heartburn (3546 +/- 1353 ) groups. Baseline impedance values inversely correlated with reflux percent time, acid-reflux time, and acid exposure time. ConclusionAmong patients with PPI-refractory NERD, acid-reflux type was associated with lower baseline impedance compared with non-acid-reflux type and functional heartburn.