455. SHOULD THE DIAGNOSTIC THRESHOLD FOR PH MONITORING IN GASTROESOPHAGEAL REFLUX DISEASE DIFFER BETWEEN THE EAST AND THE WEST?

Abstract Background The Montreal definition's reliance on troublesome typical symptoms alone is inadequate for diagnosing 'actionable' Gastroesophageal Reflux Disease (GERD). Lyon consensus 2.0 updated conclusive evidence of GERD, incorporating Los Angeles grade B or above esophagitis and Acid Exposure Time (AET) exceeding 6% in ambulatory reflux monitoring. The Seoul Consensus 2020 presents varied opinions on applying the same standards to the Asian population. A meta-analysis determined the Asian upper limit of AET as 3.2%. This study aims to compare Lyon 1.0 and 2.0 consensus compositions and assess the sensitivity and specificity of different AET thresholds in predicting Grade B or above esophagitis. Methods Patients with refractory GERD symptoms or considering anti-reflux surgery underwent objective GERD workup, including 24-hour catheter-based or 96-hour wireless ambulatory pH monitoring, High-Resolution Manometry, and upper endoscopy. This retrospective cohort study analyzed patient data from 2011-2023, excluding those with prior anti-reflux surgery, bariatric surgery, or myotomy for achalasia. Patients were categorized based on Lyon Consensus 1.0 and 2.0 as 'Non-GERD,' 'Borderline GERD,' 'Borderline GERD with evidence,' and 'Conclusive GERD.' Sensitivity, specificity, and Area-Under-Curve (AUC) were calculated using AET thresholds of 3.2%, 4%, 6%, and 7.2% to predict Grade B or above esophagitis. Results Between July 2011 and August 2023, 257 patients underwent pH monitoring and were included in the analysis, with 247 (93.8%) being ethnic Chinese. The number of patients categorized as conclusive GERD was significantly higher in Lyon 2.0 (134, 52.1%) compared to Lyon 1.0 (109, 42.4%), p < 0.001. Sensitivity and specificity for predicting Grade B or above esophagitis were as follows: AET 3.2% (83.3%, 48.8%), AET 4% (65.3%, 52.4%), AET 6% (73.8%, 66%), AET 7.2% (69.0, 72.1%). AET 7.2% demonstrated the highest AUC of 70.6% (Figure 1). Among patients classified as conclusive GERD, 67 (50%) underwent antireflux surgery. Conclusion Using the Asian threshold of AET 3.2% yields the highest sensitivity for detecting Grade B or above esophagitis. Additionally, the AUC is higher compared to using AET 4.0%. However, it is important to note that AET alone should not be the sole parameter for diagnosing actionable GERD, as even with the lowest AET threshold of 3.2%, 16.7% of patients with Grade B or above esophagitis would be missed.