Introduction
Gastric emptying testing (GET) is used to assess gastric motility, however is non-specific and insensitive for neuromuscular disorders. Gastric Alimetry® is a new medical device combining non-invasive gastric electrophysiological mapping and validated symptom profiling.
Aims & Methods
This study aimed to assess patient-specific phenotyping using Gastric Alimetry with comparison to GET.
Patients with chronic gastroduodenal symptoms underwent simultaneous GET and Gastric Alimetry. Tests comprised a 30-minute baseline, 99mTC-labelled egg meal, and 4-hour postprandial recording. Results were referenced to normative ranges1,2. Symptoms were profiled in real-time during testing in the validated Gastric Alimetry App3, phenotyped with rule-based criteria, and compared to long-term symptom questionnaires of Rome IV criteria, Patient Assessment of Upper Gastrointestinal Symptom Severity Index (PAGI-SYM), Gastroparesis Cardinal Symptom Index (GCSI), Patient Assessment of Upper Gastrointestinal Disorders Quality of Life (PAGI-QoL), Patient Health Questionnaire-2 (PHQ-2), and State-Trait Anxiety Inventory-6 (STAI-6). Three Gastric Alimetry symptom profiles were phenotyped: i) continuous (symptoms do not correlate with meal or gastric activity); ii) gastric sensorimotor (symptoms increase within 30 minutes of the meal and decay as gastric activity decreases); and iii) Other (symptoms that do not fit the other two symptom profiles).
Results
75 patients with chronic gastroduodenal symptoms were assessed; 77% female, median age 43, median BMI 24.0. Motility abnormality detection rates were: GET 22.7% (14 delayed, 3 rapid); Gastric Alimetry spectral analysis 33.3% (14 dysrhythmic / low amplitude; 5 high amplitude; 6 abnormal frequency); combined yield 42.7%. In patients with normal spectral analysis, Gastric Alimetry symptom phenotypes included: gastric sensorimotor 17%; continuous 30%; other 53%. The sensorimotor phenotype correlated strongly with gastric amplitude (median r=0.61 vs r=0.08 and r=0.06 respectively; p=0.0002). Abnormal Gastric Alimetry phenotypes showed superior correlations with GCSI, PAGI-SYM, and STAI-6 anxiety scores (p<0.05), while Rome IV Criteria and delayed gastric emptying did not correlate (p>0.05). Delayed gastric emptying was not predictive of specific Gastric Alimetry phenotypes.
Conclusion
Gastric Alimetry generated a higher yield for motility abnormalities than GET in patients with chronic gastroduodenal symptoms. Gastric Alimetry also identified patient-specific symptom phenotypes, showing correlations with health psychology variables not observed with Rome IV and delayed gastric emptying. GET and Gastric Alimetry assess different aspects of gastric function, indicating these tests may have complementary roles.
References
1. Varghese C, Schamberg G, Calder S, et al. Normative values for body surface gastric mapping evaluations of gastric motility using gastric alimetry: Spectral analysis. American Journal of Gastroenterology 2022; Publish Ahead of Print. Epub ahead of print 2022. DOI: 10.14309/ajg.0000000000002077.
2. Abell TL, Camilleri M, Donohoe K, et al. Consensus recommendations for Gastric Emptying Scintigraphy: A joint report of the American Neurogastroenterology and Motility Society and the Society of Nuclear Medicine. Journal of Nuclear Medicine Technology; 36: 44–54.
3. Sebaratnam G, Karulkar N, Calder S, et al. Standardized system and app for continuous patient symptom logging in gastroduodenal disorders: Design, implementation, and validation. Neurogastroenterology & Motility 2022; 34. Epub ahead of print 2022. DOI: 10.1111/nmo.14331.
Disclosure
Greg O'Grady, Armen Gharibans and Peng Du hold intellectual property and grants in gastric electrophysiology and are Directors of University of Auckland spin-out companies (Greg O'Grady: Alimetry, Insides Company; Armen Gharibans: Alimetry; Peng Du: FlexiMap); Stefan Calder, Gabriel Schamberg, Stephen Waite, and Christopher N. Andrews are members of Alimetry. The remaining authors have no relevant conflicts of interest to declare.