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Introduction Chronic gastroduodenal conditions are heterogeneous and difficult to categorise based on symptoms or gastric emptying. Body Surface Gastric Mapping (BSGM) offers a non-invasive test of gastric function, combining gastric electrophysiology, real-time symptom reporting, and psychological assessments. Using structured literature reviews and iterative expert consensus, an International Working Group derived the Auckland Classification for BSGM and applied it within a multicenter clinical cohort.Methods A systematic review synthesised evidence from clinical, translational, and validation research. Based on this, phenotype categories were established using BSGM spectral metrics, symptom tags, and Alimetry Gut Brain Wellbeing scores and mapped to putative mechanisms from the literature. The deterministic phenotyping classification was subsequently tested on a patient cohort with chronic gastroduodenal disorders, including stratifying total symptom burden and mental health scores.Results The systematic review identified 50 articles published on BSGM. Expert consensus endorsed six principal phenotypes with distinct pathophysiological correlates: ‘Dysrhythmic’ (rhythm stability <0.25, associated with gastric neuromuscular dysfunction), ‘High Frequency’ (gastric frequency >3.35, associated with vagal impairment), ‘Low Meal Response’ (low meal response ratio, linked to post-prandial hypomotility), ‘Sensorimotor’ (sensorimotor correlation >0.5, linked to visceral sensitivity), ‘Continuous’ (normal spectral metrics with meal and amplitude independent symptoms, often associated with high psychological comorbidity), and Delayed Symptom Onset (onset of symptoms after completion of gastric meal cycle, suggesting small intestinal contributions). When applied to a cohort of 364 patients (80% female), 72.3% were successfully phenotyped, with 34 (9%) Dysrhythmic, 29 (8%) High Frequency, 49 (13%) Low Meal Response, 77 (21%) Sensorimotor, 64 (18%) Continuous, and 10 (3%) Delayed Symptom Onset. Phenotyped patients had significantly higher total symptom burden scores (21.1 (IQR 11.5-31.4) vs 11.1 (IQR 3.5-20.1); p<0.001; figure 1A) and Alimetry Gut Brain Wellbeing scores (available in n=193; 20 (IQR 13-25) vs 16 (IQR 9-22); p=0.01; figure 1B).Conclusions The Auckland Classification establishes an international consensus and evidence-based framework for BSGM adoption in clinical and research contexts. This framework is suitable for use in prospective therapeutic trials to guide personalised therapy based on specific disease mechanisms.Abstract P391 Figure 1Difference in symptoms and psychological comorbidity stratified by Auckland Classification version 1.0. A) Total symptom burden in the entire cohort (n=364); B) Alimetry Gut Brain Wellbeing overall score in subset (n=193)