Can Esophageal Baseline Impedance Predict Proton Pump Inhibitor Response in Gastroesophageal Reflux Disease?

c 2018 The Korean Society of Neurogastroenterology and Motility J Neurogastroenterol Motil, Vol. 24 No. 1 January, 2018 www.jnmjournal.org Gastroesophageal reflux disease (GERD) is characterized by reflux of stomach contents and causes unpleasant symptoms and complications. Proton pump inhibitors (PPIs) are widely used to treat GERD and significantly reduce gastric acid secretion. However, despite PPI therapy, up to 40% of patients report persistent GERD symptoms. Some studies have attempted to predict which patients will have a poor response to PPI treatment. A recently published review article reported that poor response to PPI treatment is related to a PPI-metabolizer genotype, CYP, and requires combined adjunctive therapy. Adjusting treatment in patients with the PPI-metabolizer genotype or switching to a CYP2C19-independent PPI is a simple way to increase the PPI response. In addition, the use of adjunctive agents may be considered when the physiological mechanism of PPI nonresponse is suspected. For such patients, recent research focused on whether the diagnosis is truly correct and the degree of treatment response can be predicted. According to the recent implementation of a pH monitoring method combined with baseline impedance (BI), and depending on the degree of acid exposure and esophageal hypersensitivity highlighted in the Rome IV criteria for functional esophageal disorders, patients with suspected GERD with typical chest pain and regurgitation are divided into 4 subtypes: erosive esophagitis, non-erosive reflux disease (NERD), reflux hypersensitivity, and functional heartburn (FH). Especially when using mean nocturnal BI in the distal esophagus for patients with heartburn, several studies showed that the value of BI and degree of reflux showed a negative correlation and the mean BI level was statistically significantly lower in the PPI-responsive group than in the non-responsive group. Therefore, esophageal BI is used to predict the therapeutic effect of PPI related to severity of acid exposure. However, there is still insufficient evidence to standardize this strategy. Along with the BI, the concept of intercellular space diameter (ISD) has recently been studied. Histologically, dilated intercellular space (DIS) is frequently observed in GERD patients. In addition, JNM J Neurogastroenterol Motil, Vol. 24 No. 1 January, 2018 pISSN: 2093-0879 eISSN: 2093-0887 https://doi.org/10.5056/jnm17138 Editorial Journal of Neurogastroenterology and Motility