Validation of Lyon 2.0 Gastroesophageal Reflux Disease Consensus: Limited Clinical Utility of Mean Nocturnal Basal Impedance in Koreans.

Background/aims: The Lyon Consensus 2.0 (Lyon 2.0) revised gastroesophageal reflux disease (GERD) definitions, incorporating Los Angeles (LA) grade B as diagnostic and mean nocturnal basal impedance (MNBI) as supplementary evidence. Asian populations show differing impedancepH thresholds, with lower acid exposure time (AET) and higher MNBI values. The clinical validity of MNBI in Asian GERD patients remains uncertain. This study evaluated Lyon 2.0's applicability to Korean patients.

Methods: From January 2021 to August 2023, GERD-suspected patients underwent endoscopy, manometry, and pH testing. MNBI was measured 5 cm above the lower esophageal sphincter. Patients with major motor disorders, organic diseases, or prior foregut surgery were excluded. GERD was defined by AET ≥ 4% or LA grades B-D; non-GERD by AET < 4%, LA grade A or normal Z line with < 40 reflux episodes/day. The optimal MNBI threshold was determined via receiver operating characteristic curve analysis.

Results: Among 427 patients (mean age 57.7 ± 13.8 years, 37.2% male), 59 (13.8%) had GERD (10 endoscopically confirmed, 54 by AET ≥ 4%). Non-GERD accounted for 63.5% (n = 271), with 22.7% (n = 97) in the borderline group. MNBI correlated negatively with AET (r = -0.482, P < 0.01) and LA grade (r = -1.390, P = 0.005). The optimal MNBI threshold for GERD was 2167 Ω (sensitivity 0.86, specificity 0.75). Three LA grade A cases were reclassified as GERD-positive using this threshold.

Conclusion: MNBI significantly correlated with AET and LA grades, highlighting its diagnostic value in Korean GERD patients. However, regional variations suggest higher MNBI thresholds than Lyon 2.0 recommendations, warranting further studies to refine criteria for Asian populations.