Esophageal intraluminal baseline impedance is associated with severity of acid reflux and epithelial structural abnormalities in patients with gastroesophageal reflux disease

The esophageal intraluminal baseline impedance may be used to evaluate the status of mucosa integrity. Esophageal acid exposure decreases the baseline impedance. We aimed to compare baseline impedance in patients with various reflux events and with different acid-related parameters, and investigate the relationships between epithelial histopathologic abnormalities and baseline impedance. A total of 229 GERD patients and 34 controls underwent 24-h multichannel intraluminal impedance and pH monitoring (MII-pH monitoring), gastroendoscopy, and completed a GERD questionnaire (GerdQ). We quantified epithelial intercellular spaces (ICSs) and expression of tight junction (TJ) proteins by histologic techniques. Mean baseline values in reflux esophagitis (RE) (1752 +/- A 1018 Omega) and non-erosive reflux disease (NERD) (2640 +/- A 1143 Omega) were significantly lower than in controls (3360 +/- A 1258 Omega; p < 0.001 and p = 0.001, respectively). Among NERD subgroups, mean baselines in the acid reflux group (2510 +/- A 1239 Omega) and mixed acid/weakly acidic reflux group (2393 +/- A 1009 Omega) were much lower than in controls (3360 +/- A 1258 Omega; p = 0.020 and p < 0.001, respectively). The mean baseline in severe RE patients was significantly lower than in mild RE patients (LA-C/D vs. LA-A/B: 970 +/- A 505 Omega vs. 1921 +/- A 1024 Omega, p < 0.001). There was a significant negative correlation between baseline value and acid exposure time (AET) (r = -0.41, p < 0.001), and a weak but significant correlation (r = -0.20, p = 0.007) between baseline value and weakly AET. Negative correlations were observed between ICS and the baseline impedance (r = -0.637, p < 0.001) and claudin-1 and the baseline impedance (r = -0.648, p < 0.001). Patients with dominant acid reflux events and with longer AET have low baseline impedance. Baseline values are correlated with esophageal mucosal histopathologic changes such as dilated ICS and TJ alteration.