Introduction

The definition of actionable GERD according to the Lyon v2.0 Consensus in patients with inconclusive diagnosis of GERD (acide exposure time [AET] that ranges among 4 and 6%) requires adjunctive metrics such as mean nocturnal baseline impedance (MNBI), total number of reflux events and reflux/symptom association (RSA) indices.

Aims & Methods

The aim of this study was to identify patients most likely to have a positive metrics on prolonged 96 hours wireless pH monitoring (PWPM) among patients with inconclusive AET values on 24 hours pH-impedance monitoring (MII-pH) off PPI. Secondary aim was to identify other MII-pH parameters predictive of GERD diagnosis.
This was a retrospective study that collected a series of patients with typical GERD presentation. All patients underwent:

• Endoscopy, to exclude the presence of erosive esophagitis (grade B or higher according to Los Angeles classification);
• Esophageal HRM to rule out motility disorders and calculate: esophago-gastric junction contractile integral (EGJ-CI), esophagogastric junction (EGJ) morphology, and Milan Score.
• MII-pH monitoring to assess AET values, total reflux events, MNBI, RSA and Lyon Score.
• PWPM performed for 96 hours within 1 month after MII-pH.
• Treatment (PPI) response was evaluated with VAS scale during follow-up.

Patients were categorized into 2 different groups: those with vs. without conclusive GERD on PWPM. MII-pH and HRM parameters were compared between the two groups.

Results

51 consecutive patients (24 female; median age 51yrs) were included: 15 patients (8 female, 49yrs, BMI 22.8) had non-conclusive PWPM for GERD (negative), while GERD was confirmed (positive) in 36 patients (16 female, 53yrs, BMI 26.8). There were no significant demographic differences. Prevalence of heartburn and regurgitation were comparable in both groups. Patients with confirmed GERD were more likely to respond to PPI treatment (positive 69% vs negative 59%, p=0.014).
Patients with confirmed GERD on PWPM had a higher AET (p<0.001), total reflux events (p < 0.001), and lower MNBI (p < 0.001) on MII-pH; lower EGJCI, and higher prevalence of hiatal hernia (p<0.001) on HRM; higher Milan SCORE (p < 0.001), and higher Lyon Score (p<0.01) compared to negative PWPM. See Table 1.

	Negative PWPM 96h (15)	Positive PWPM 96h (36)	P
PPI response (VAS)	59 (39, 69)	59 (39, 69)	0.014
Hiatal Hernia	0 (0%)	18 (50%)	<0.001
EGJ-CI	63 (46, 87)	20 (11, 30)	<0.001
MILAN SCORE	48 (42, 53)	196 (173, 234)	<0.001
AET (MIIpH)	1.60 (1.10, 2.90)	5.20 (3.75, 5.85)	<0.001
N REFLUX	25 (19, 29)	44 (36, 54)	<0.001
Symptom Index (+)	0 (0%)	10 (28%)	0.024
MNBI	2871 (2269, 3165)	1055 (910, 1247)	<0.001
LYON SCORE	1.00 (0.00, 2.00)	5.00 (3.00, 6.00)	<0.001

ROC analysis showed that MNBI is the strongest predictor of GERD (AUC 1.0), followed by the Milan (AUC 0.99, Sens 100%, Spec 93%) and Lyon Scores (AUC 0.97, Sens 80%, Spec 100%), total number of reflux events (AUC 0.9, Sens 86%, Spec 93%)
A subgroup of 13 patients (7 female) with an AET<4% but MNBI values <1500 Ohms on MII-pH, all (100%) were confirmed as having GERD on 96h PWPM.

Conclusion

We demonstrate that a low MNBI value on MII-pH is the strongest predicting factor of conclusive GERD diagnosis in patients with borderline or normal AET values. A sub-group of patients with AET <4% but very low MNBI (<1500 Ohms) on MII-pH showed conclusive GERD during subsequent 96 hour PWPM, establishing its longitudinal role in confirming reflux disease.

Disclosure

Conference Speech: Reckitt Benckiser; Malesci; Dr Falk, PharmaLine, AlfaSigma, Sanofi-Genzyme.
Advisory Board: Dr Falk; Astra Zeneca; Sanofi Genzyme, AlfaSigma
Research grant: Dr Falk; Sanofi Genzyme