Background

There is a lack of prior studies assisting the diagnostic yield of parameters like percent acid exposure time (AET), DeMeester score, and MNBI in post bariatric surgery patients. Our study aims to compare these diagnostic variables between patients with and without bariatric surgery.

Methods

A retrospective analysis of Creighton University Medical Center patients aged 19-89 who underwent multichannel intraluminal impedance pH (MMI-pH) or Bravo (48 or 96 hours) monitoring between January 1, 2017 - August 31, 2023. Exclusions included motility disorders, prior anti-reflux procedures and monitoring on PPI. Patient characteristics and monitoring outcomes were stratified by bariatric surgery history ('Not Bariatric' vs 'Bariatric'). Comparisons utilized logistic regression, Poisson regression, or two-part models, presented for unadjusted and adjusted models controlling for patient characteristics.

Results

AET, DeMeester and MNBI were statistically similar between bariatric and non-bariatric patients (Table 2). Bariatric cases exhibited higher AET while supine (3.50% vs 1.69%, p = 0.013), weakly acid refluxes (37.07 vs 17.79, p < 0.001), and total refluxes (52.89 vs 40.76, p < 0.001), but lower acid and nonacid refluxes than non-bariatric cases (Table 2). Among 31 post-bariatric patients with negative total AET and DeMeester scores, 20 had a positive MNBI.

Conclusions

AET and DeMeester seem to have similar diagnostic utility in patients with and without bariatric surgery. Incorporating MNBI enhanced GERD detection by 42% in post-bariatric patients. Considering MII-pH testing alongside standard Bravo testing may improve diagnoses and treatment in this population.