Validation of a Gastric-Juice-Analysis-Based Approach to H. pylori Diagnosis

<b>Background</b>: Although the incidence of <i>H. pylori</i> infection is decreasing globally, it is not completely negligible. Because <i>H. pylori</i> infection is associated with various pathologies, ranging from peptic ulcer disease to neoplastic lesions, research into and treatment of <i>H. pylori</i> infections remain important. <b>Objectives</b>: We aimed to assess the diagnostic performance of gastric juice analysis (Endofaster^®) for the detection of <i>H. pylori</i> in patients undergoing esophagogastroduodenoscopy (EGDS), using conventional histology as the reference standard. Our secondary objectives were to identify the optimal ammonium concentration thresholds for defining positive and negative results and to propose a clinical flowchart to support patient management. <b>Methods</b>: The diagnostic accuracy of Endofaster was first analyzed using an unmatched training cohort comprising an equal number of <i>H. pylori</i>-positive patients (n = 30) and negative controls (n = 30) who underwent EGDS. The derived thresholds were subsequently evaluated in an independent validation cohort of patients who underwent EGDS with Endofaster. Histological examination is the gold standard for <i>H. pylori</i> diagnosis. <b>Results</b>: In the training cohort, an ammonium concentration cut-off of 62 ppm/mL yielded a sensitivity of 90% (95% CI: 74-97%) for ruling out <i>H. pylori</i> infection. For confirming infection, the optimal cut-off was 100 ppm/mL, corresponding to a specificity of 95% (95% CI: 83-99%). Ammonium values > 62 and <100 ppm/mL were considered indeterminate, suggesting gastric biopsy was required for confirmation. The validation cohort included 196 patients (mean age: 59.9 ± 12.7 years), with a histology-based <i>H. pylori</i> prevalence of 19%. In this cohort, Endofaster^® demonstrated a sensitivity of 70% (95% CI: 51-85%) and a specificity of 93% (95% CI: 88-97%). Indeterminate results were observed for 29 patients (15%). <b>Conclusions</b>: Endofaster^® provides a largely reliable diagnosis of <i>H. pylori</i> infection during EGDS when a decision-making approach is applied, allowing gastric biopsies to be reserved for indeterminate cases only.