Lower mean nocturnal baseline impedance in erosive reflux disease, Barrett's Esophagus, and elevated body mass index compared to nonerosive reflux disease.

Diagnosing gastroesophageal reflux disease (GERD) remains challenging in patients with inconclusive endoscopic findings or acid exposure time. Mean nocturnal baseline impedance (MNBI) is a diagnostic metric to delineate pathological GERD. This study evaluates MNBI in relation to GERD phenotypes, antisecretory medication use, symptomatology, and other covariates to validate its integration into recommendations in light of Lyon consensus updates. We conducted a retrospective analysis of 550 patients who underwent esophagogastroduodenoscopy and 24-hour pH-impedance testing. A multivariate linear model inferred the association between medication status and MNBI, adjusting for covariates. Interaction terms determined moderation of patient medication status on MNBI by other clinical covariates. Medication status significantly influenced MNBI, independent of covariates. Medicated patients had mean MNBI 0.52 kΩ greater (95% CI: 0.27-7.8, P < 0.001) than non-medicated patients. MNBI was 0.78 kΩ lower (95% CI: -1.2 to -0.41, P < 0.001) in patients with erosive disease and 1.0 kΩ lower (95% CI: -1.5 to -0.5, P < 0.001) in those with Barrett's esophagus. Additionally, MNBI decreased by 0.02 kΩ for every one-unit body mass index increase (95% CI: -0.04 to -0.01, P = 0.006). This study validates lower MNBI as a potential surrogate marker for GERD, particularly in more erosive presentations. Increased MNBI in medicated patients highlights antisecretory therapy as a potential confounding factor, reinforming the need for off-therapy testing. The study is strengthened by its large population, though limited by retrospectivity. The findings support both MNBI as a valuable diagnostic tool in GERD assessment and the need to further standardize MNBI cutoffs.