METHODS: A population of 295 consecutive patients undergoing HRM and pH-study for persistent typical or atypical GERD symptoms was prospectively enrolled to build a model and a nomogram that provides a risk score for AET > 6%. Collected HRM data included IEM, EGJ-CI, EGJ type and SLR. A supplemental cohort of patients undergoing HRM and pH-study was also prospectively enrolled in 13 high-volume esophageal function laboratories across the world in order to validate the model. Discrimination and calibration were used to assess model's accuracy. Gastroesophageal reflux disease was defined as acid exposure time >6%.

RESULTS: Out of the analyzed variables, SLR response and EGJ subtype 3 had the highest impact on the score (odd ratio 18.20 and 3.87, respectively). The external validation cohort consisted of 233 patients. In the validation model, the corrected Harrel c-index was 0.90. The model-fitting optimism adjusted calibration slope was 0.93 and the integrated calibration index was 0.07, indicating good calibration.

CONCLUSIONS: A novel HRM score for GERD diagnosis has been created and validated. The MS might be a useful screening tool to stratify the risk and the severity of GERD, allowing a more comprehensive pathophysiologic assessment of the anti-reflux barrier.

DESIGN: Of 541 studies performed worldwide using two different systems (Diversatek, USA, and Laborie, Netherlands), 150 tracings with oesophageal diagnoses, behavioural disorders and study-related artefacts were excluded. The remainder studies were subject to two reviewer consensus analysis, in-person or through video conference, consisting of editing meals and pH drops, identification of impedance reflux and postreflux swallow-induced peristaltic wave (PSPW) using strict pre-established criteria and measurement of distal mean nocturnal baseline impedance (MNBI).

RESULTS: Consensus analysis was performed in 391 tracings (age 32.7 years, range 18-71, 54.2% female). Normative thresholds were significantly different between Diversatek and Laborie (total acid exposure time: 2.8% and 5%; reflux episodes: 55 and 78; MNBI at 3 cm: 1400 and 1500 ohms, at 5 cm: 1400 and 1800 ohms). Males had higher acid exposure, more reflux episodes and lower MNBI. Significant regional differences were identified, including higher PSPW scores in Western countries, and higher MNBI in Asia using Diversatek, and higher acid exposure in the Netherlands, higher MNBI in Asia and South Africa, and lower MNBI in Turkey using Laborie.

METHODS: Adult patients with persistent gastroesophageal reflux disease (GERD) symptoms undergoing HRM and pH-impedance or wireless pH study off proton pump inhibitor were prospectively studied between July 2021 and March 2022. After the HRM Chicago 4.0 protocol, patients were requested to elevate 1 leg at 45º for 5 seconds while supine. The SLR maneuver was considered effective when intra-abdominal pressure increased by 50%. IEPs were recorded 5 cm above the lower esophageal sphincter at baseline and during SLR. GERD was defined as AET greater than 6%.

RESULTS: The SLR was effective in 295 patients (81%), 115 (39%) of whom had an AET greater than 6%. Hiatal hernia (EGJ type 2 or 3) was seen in 135 (46%) patients. Compared with patients with an AET less than 6%, peak IEP during SLR was significantly higher in the GERD group (29.7 vs 13.9 mm Hg; P < .001). Using receiver operating characteristic analysis, an increase of 11 mm Hg of peak IEP from baseline during SLR was the optimal cut-off value to predict an AET greater than 6% (area under the receiver operating characteristic curve, 0.84; sensitivity, 79%; and specificity, 85%), regardless of the presence of hiatal hernia. On multivariable analysis, an IEP pressure increase during the SLR maneuver, EGJ contractile integral, EGJ subtype 2, and EGJ subtype 3, were found to be significant predictors of AET greater than 6% CONCLUSIONS: The SLR maneuver can predict abnormal an AET, thereby increasing the diagnostic value of HRM when GERD is suspected.