The Role of Distal Mean Nocturnal Baseline Impedance in Differentiating GERD Phenotypes

Background & Aims: Gastroesophageal reflux disease (GERD) is one of the most frequent digestive pathologies. The current diagnosis of GERD either by trial of proton pump inhibitors (PPIs), endoscopy or by multichannel impedance pH study (MII/pH) has limitations. Our study aims to show if mean nocturnal baseline impedance (MNBI) can differentiate between the GERD phenotypes.Methods: We recruited 62 patients who underwent upper digestive endoscopy and MII/pH, with some patients undergoing esophageal manometry to exclude motility disorders. Patients were separated into 4 GERD phenotypes: erosive reflux disease (ERD), non-erosive reflux disease (NERD), reflux hypersensitivity (RH) and functional heartburn (FH). Proximal MNBI was calculated as the mean value of the proximal 2 channels (Z1 and Z2), and distal MNBI was calculated as the mean value of the distal 4 channels (Z3, Z4, Z5, Z6).Results: Distal MNBI can help distinguish the abnormal acid exposure time (AET) phenotypes (ERD, NERD) from normal AET phenotypes (RH, FH) with a decent performance (AUROC 0.857). Distal MNBI has good accuracy in separating ERD from other phenotypes (AUROC 0.872). Furthermore, distal MNBI can differentiate FH from ERD, NERD, RH with good accuracy (AUROC 0.879), and on top of that is able to separate FH from RH (AUROC 0.817).Conclusions: Our study showed that distal MNBI is a good method of differentiating GERD phenotypes and should be taken into consideration in future studies to assess its validity in helping physicians make the correct diagnosis.