Comparison of mucosal impedance measurements throughout the esophagus and mucosal eosinophil counts in endoscopic biopsy specimens in eosinophilic esophagitis

Background and Aims: Assessing eosinophilic esophagitis (EoE) activity from limited esophageal mucosal biopsy samples has been questioned. Here our aim was to compare mucosal impedance (MI) throughout the esophagus and eosinophil counts in endoscopic biopsy samples in EoE. Methods: We compared 20-site MI using a balloon catheter in the esophagus and eosinophils per high-power field (eos/HPF) in esophageal mucosal biopsy samples. Data are summarized as median (interquartile range) comparing control subjects and EoE using Mann-Whitney rank sum test and between endoscopic reference score and MI (minimal and average) using rank Spearman correlation. Results: Ten adult control patients (ages 38-70) and 23 EoE patients (ages 21-80, 18 active) were studied. The mean (range) pan-esophageal MI in control subjects was significantly higher (6435 ohms [4546-7301]) compared with EoE patients (2004 ohms [1437-2546],P <.001). In control patients 172 of 180 (95.6%) individual impedance measurements (18 per patient) were normal when compared with 126 of 432 (29.2%) measurements in EoE. No EoE patient had uniformly normal MI. MI varied widely, with 19 of 23 patients having values above and below 2300 ohms (normal) regardless of EoE activity. Correlation of maximim eos/HPF with minimum and average MI per patient was r=.243, P=.072 and r=.358, P=.086, respectively. Of 5 patients with inactive EoE, 3 had >50% abnormal MI segments. Correlation coefficients of the endoscopic reference score with minimum and average MI were r=.154, P=.47 and r=.27, P=.20, respectively. The procedure was <5 minutes without adverse events. Conclusions: MI is lower in the esophagus of EoE patients compared with control subjects with poor correlation between peak esophageal eosinophil counts, EoE activity, and MI. Segmental esophageal MI provides a unique marker of esophageal dysfunction in EoE. (Clinical trial registration number: NCT02995395")