← Issue №11/ week of Sep 13, 2026/Endoscopy

Association of Mean Nocturnal Baseline Impedance and AFS EGJ Grading With AET-Defined Reflux Burden in Korean Patients.

From GI Signals issue №11: what this paper found, what it changes, and where it sits against the current standard of care, reviewed by Simon Mathews, MD.

Endoscopy retrospective · n=224 · Sep 7, 2026 · J Gastro Hep · IF 3.5

Association of Mean Nocturnal Baseline Impedance and AFS EGJ Grading With AET-Defined Reflux Burden in Korean Patients.

DiagnosticGERDbiomarker
Clinical takeawayIn patients with borderline acid exposure (AET 4-6%), lower MNBI (< 1618 Ω) supports diagnosis of pathological GERD and consideration of treatment; this threshold may help navigate the diagnostic gap between Lyon Consensus 2.0 (AET ≥ 6%) and East Asian standards (AET ≥ 4%). However, these cutoffs are internally derived and require external validation before routine adoption in other populations.
What it foundLower mean nocturnal baseline impedance independently predicted pathological AET ≥ 6% (OR 0.84 per 100-unit increase, p < 0.001), with an exploratory cutoff of 1618 Ω achieving AUC 0.883.
ContextMNBI is already used to characterize reflux burden, but the diagnostic gray zone between international and regional AET thresholds has created clinical uncertainty in borderline cases. This study provides a physiological marker to resolve that ambiguity in a Korean cohort, though the cutoff remains unvalidated externally.
Refinessuggested applicable standard· American College of Gastroenterology (ACG), ACG Clinical Guideline for the Diagnosis and Management of Gastroesophageal Reflux Disease (Katz PO, Dunbar KB, Schnoll-Sussman FH, Greer KB, Yadlapati R, Spechler SJ), Am J Gastroenterol 2022;117(1):27-56

Decision at stakehow to characterize GERD in patients with borderline acid exposure time in the 4-6% AET gray zone

Where GERD is suspected but unclear and endoscopy shows no objective evidence, perform reflux monitoring OFF therapy to establish the diagnosis (strong, low); conversely, do NOT perform off-therapy reflux monitoring solely as a diagnostic test in patients already known to have LA grade C or D esophagitis or long-segment Barrett's, because the diagnosis is already established (strong, low).

From our summary of this standard, unedited — the part the paper bears on. marks omitted text. Our wording, not the guideline's; read the source for its own text.

Our full summary of this standard

In patients with classic GERD symptoms (heartburn, regurgitation) and no alarm symptoms, give an 8-week trial of empiric PPI ONCE DAILY before a meal (strong, moderate evidence); administer PPI 30-60 minutes before a meal rather than at bedtime (strong, moderate). Endoscopy is the FIRST test in patients presenting with dysphagia or other alarm symptoms, the guideline names weight loss and GI bleeding, and also in patients with multiple risk factors for Barrett's esophagus (strong, low). If classic symptoms respond to the 8-week trial, attempt to discontinue the PPI (conditional, low); for patients without erosive esophagitis or Barrett's whose symptoms resolved, an attempt at discontinuation should be made; patients requiring maintenance should take the lowest effective dose. If symptoms do not respond adequately to the 8-week trial, or return on discontinuation, perform diagnostic endoscopy, ideally after PPIs are stopped for 2-4 weeks (strong, low). Where GERD is suspected but unclear and endoscopy shows no objective evidence, perform reflux monitoring OFF therapy to establish the diagnosis (strong, low); conversely, do NOT perform off-therapy reflux monitoring solely as a diagnostic test in patients already known to have LA grade C or D esophagitis or long-segment Barrett's, because the diagnosis is already established (strong, low). In refractory GERD, optimize PPI therapy first (strong, moderate); then pH monitoring OFF PPIs if GERD was not previously established by pH study, long-segment Barrett's, or LA grade C/D esophagitis, versus impedance-pH ON PPIs where GERD is already established but symptoms persist on twice-daily PPI (both conditional, low). Before antireflux surgery or endoscopic therapy, HRM is recommended to rule out achalasia and absent contractility, with provocative testing (e.g., multiple rapid swallows) to identify contractile reserve in ineffective esophageal motility; on-therapy reflux monitoring is suggested before intervention in patients with prior objective GERD findings who remain symptomatic. Antireflux surgery by an experienced surgeon is an option for patients with OBJECTIVE evidence of GERD, with severe esophagitis (LA C/D), large hiatal hernia, or persistent troublesome symptoms benefiting most; TIF is suggested only for troublesome regurgitation or heartburn in patients who do not wish to undergo antireflux surgery and who are WITHOUT severe esophagitis (LA C/D) or hiatal hernia >2 cm. For extraesophageal symptoms WITHOUT typical GERD symptoms, perform reflux testing BEFORE starting PPI therapy (strong, moderate); with concomitant typical symptoms, consider twice-daily PPI for 8-12 weeks before further testing (conditional, low). Lifestyle: weight loss in overweight/obese patients (strong, moderate); avoid meals within 2-3 hours of bedtime, avoid tobacco, avoid trigger foods, and elevate the head of the bed for nighttime symptoms (all conditional, low).

American College of Gastroenterology (ACG), ACG Clinical Guideline for the Diagnosis and Management of Gastroesophageal Reflux Disease (Katz PO, Dunbar KB, Schnoll-Sussman FH, Greer KB, Yadlapati R, Spechler SJ), Am J Gastroenterol 2022;117(1):27-56 · reviewed 2026-07-23 ↗
Chae YR … Lee YC · Journal of Gastroenterology and Hepatology · IF 3.5 · PubMed ↗Permalink
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