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Observational Study
. 2025 May 20;25(1):388.
doi: 10.1186/s12876-025-03986-w.

Better diagnostic accuracy for GERD observed with the new MNBI cutoff: an observational study in Vietnam

Hang Dao Viet  1   2   3 , Hue Luu Thi Minh  4 , Long Hoang Bao  4   5 , Phuong Do Nhat  4 , Long Dao Van  6   7   4
Affiliations
Observational Study

Better diagnostic accuracy for GERD observed with the new MNBI cutoff: an observational study in Vietnam

Hang Dao Viet et al. BMC Gastroenterol. .

Abstract

Background: Mean nocturnal baseline impedance (MNBI) is a novel metric for multichannel ambulatory impedance and pH (MI-pH) monitoring used to diagnose gastroesophageal reflux disease (GERD); however, its thresholds vary among different geographic areas and measuring systems. This study analyzed MI-pH data from Vietnamese patients to assess the diagnostic utility of novel MNBI thresholds in identifying GERD.

Methods: This retrospective study included 133 patients suspected of having GERD who underwent upper gastrointestinal endoscopy, esophageal high-resolution manometry (HRM) and 24-hour MI-pH monitoring (Laborie). The subjects were divided into 3 groups based on the acid exposure time (AET) index (abnormal, inconclusive and normal AET). The mean MNBI and the prevalence of abnormal MNBI values were compared within groups, and the diagnostic accuracy of this index for diagnosing GERD was evaluated via receiver operating characteristic (ROC) curves and their area under the curve (AUC).

Results: MNBI was significantly lower in patients with abnormal AET. The prevalence of MNBI < 2292 Ohms and MNBI < 1500 Ohms were greater in patients with abnormal AET (91.2% and 79.4%, respectively). The percentage of MNBI > 2500 Ohms was 44.4% in patients with normal AET but only 2.9% in patients with abnormal AET. MNBI had the highest AUC in discriminating abnormal AET (0.90, p < 0.001) in comparison with other metrics on MI-pH monitoring. The new cutoff value of 1500 Ohms had lower sensitivity but higher specificity than the previous threshold of 2292 Ohms. A multivariable regression analysis revealed that an MNBI < 1500 Ohms and total number of reflux events > 80/day were significantly associated with abnormal AET (> 6%).

Conclusions: Among Vietnamese patients with suspected GERD, the new MNBI cutoff of > 1500 Ohms had high sensitivity and specificity in diagnosing GERD, while the cutoff of 2500 Ohms could rule out this disease.

Keywords: Esophageal pH monitoring; Gastroesophageal reflux disease; Mean nocturnal baseline impedance.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: This observational study utilized ethics approval of the mentioned-above national project by the Institutional Review Board of Dinh Tien Hoang Institute of Medicine ( Approval No.IRB-1909). The study was performed in accordance with the Declaration of Helsinki principles. All participants provided written informed consent in the first period of the study’s data collection. During the second period, no study procedures were conducted and all patients followed routine procedures at our clinic. Therefore, the data collected from this period was of retrospective nature and informed consent is not required. Consent for publication: All participants provided written informed consent for the use of data in research activities in the first period of the study’s data collection. During the second period, no study procedures were conducted and all patients followed routine procedures at our clinic. Therefore, the data collected from this period was of retrospective nature and informed consent is not required. Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Diagnostic accuracy of MNBI for diagnosing GERD: (a) ROC curves of MNBI, PSPW index, and TRs for differentiating abnormal AET from inconclusive AET from normal AET; (b) ROC curves of AET, MNBI, PSPW index, and TRs for differentiating ERD from NERD on endoscopy
See this image and copyright information in PMC

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