Advancements in the use of 24-hour impedance-pH monitoring for GERD diagnosis
Introduction
Gastroesophageal reflux disease (GERD) is a chronic and benign condition, affecting up to 20% of the general population in western countries while it is less prevalent in Asian populations [1]. According to the Montreal classification [2], it develops when the reflux into the esophagus of gastric contents (meals and secretions) causes troublesome symptoms and/or complications.
Until the end of the second millennium, GERD was identified with erosive esophagitis (EE), but in the past two decades we have realized that the majority of patients with this illness do not present any inflammatory lesions of the distal part of the esophagus at endoscopy [3]. This non-erosive form of GERD has been named as NERD (non-erosive reflux disease) on the exclusive basis of the absence of endoscopic damage, but subsequent functional studies have clearly shown that it is markedly heterogeneous from a pathophysiological point of view, because we can distinguish various phenotypes [4]: patients with acid excess (true NERD); patients with normal acid, but positive correlation between heartburn and reflux episodes (reflux hypersensitivity) and patients with normal acid, but without any relationship between symptoms and reflux events (functional heartburn = FH). In other words, the most typical symptom of GERD, that is heartburn, can be due not only to acid, but also to other factors not depending on increased esophageal acid exposure [5].
Beyond the typical symptoms of GERD (heartburn and regurgitation), this disorder can manifest with extraesophageal symptoms (chronic cough, hoarseness, asthma), but this association has been questioned in last years, because it seems to be much less frequent than previously estimated [6].
Section snippets
Diagnosis of GERD
Taking into consideration the above complexity of the phenotypic characterization of GERD, the diagnosis of this disease remains difficult also in 2021, because we continue to complain the lack of a “gold standard” examination, which permits to assess with certainty the detection of gastroesophageal reflux as the cause of symptoms we generally attribute to GERD, but they are shared by many other disorders. As a consequence, we have to rely on many diagnostic options, which present advantages
Conclusions
Taking in mind that a “gold standard” test to diagnose this disease is still lacking, impedance-pH monitoring over 24 h is actually considered the best method to assess GERD and has contributed to reveal the heterogeneous pathophysiology of NERD patients, who represent the majority of GERD (about 70%). In particular, impedance-pH monitoring allows to categorize NERD patients in “true” NERD, reflux hypersensitivity and FH, thus helping to exclude the latter disorder from the NERD realm and
Authors’ contribution
EM, VS, ES: design of the study, data collection, writing of the manuscript, approving final version; MG, MF, MR, BB: data collection, writing of the manuscript, approving final version.
Guarantor of the article
Edoardo Savarino.
Financial support
None.
Conflict of interest statement
ES declares lecture fees from Takeda, Janssen, MSD, Abbvie, Malesci, Sofar, and consulting fees from BMS, Gilead, Takeda, Janssen, MSD, Reckitt Benckiser, Sofar, Unifarco, SILA, Oftagest, Diadema; the remaining authors have no disclosures.
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