Can the Mean Nocturnal Baseline Impedance/Acid Exposure Time Ratio Serve as a Novel Parameter for the Definitive Diagnosis of Pathological Reflux?

<b>Background:</b> According to the Lyon Consensus 2.0, acid exposure time (AET) greater than 6% is considered definitive evidence of pathological reflux, while mean nocturnal baseline impedance (MNBI) serves as supportive evidence. Given the limitations in diagnostic accuracy when MNBI and AET are used separately, this study aimed to evaluate the MNBI/AET ratio as a potential novel parameter and determine its optimal cut-off value for improving diagnostic performance. <b>Methods:</b> We assessed patients with typical gastroesophageal reflux symptoms who completed standardized reflux questionnaires and underwent upper gastrointestinal endoscopy, high-resolution esophageal manometry, and 24 h multichannel intraluminal impedance-pH monitoring. Diagnoses were established based on the Lyon Consensus 2.0 and Chicago Classification v4.0 frameworks. <b>Results:</b> A total of 213 patients were included. Based on the Lyon Consensus 2.0, 66 patients (31%) were diagnosed with definite gastroesophageal reflux disease (GERD), 58 (27%) showed no evidence of reflux, and 89 (42%) had borderline or supportive findings. The cut-off value for MNBI to differentiate between patients with definitive reflux and those without reflux was ≤3040 Ω (AUC [95% CI]: 0.902 [0.836-0.948]; <i>p</i> < 0.001; sensitivity = 87.88%; specificity = 84.48%). Receiver operating characteristic (ROC) analysis revealed that an MNBI/AET ratio of ≤624 (95% CI: ≤607.5-≤624.28) most effectively distinguished patients with definitive GERD from those without reflux (AUC = 0.970; 95% CI: 0.937-0.988), demonstrating high sensitivity (98.5%) and specificity (98.3%). <b>Conclusions:</b> An MNBI/AET ratio ≤ 624 effectively differentiates patients with definitive GERD from those without reflux and may serve as a novel diagnostic parameter. Incorporating this ratio into clinical practice could enhance diagnostic accuracy for pathological reflux.