Stool Antigen Test: A valuable tool for the diagnosis and confirmation of H. pylori eradication

Accurate diagnosis of H. pylori infection remains both crucial and challenging today. In line with current guidelines, confirming eradication after antibiotic treatment is essential. Diagnostic methods are traditionally divided into invasive and non-invasive approaches. Invasives rely on identifying the bacteria in stomach biopsies obtained through endoscopy (histology, rapid urease test, culture, and molecular techniques). Conversely, non-invasive methods, which are more widely used, do not require endoscopy. The 13C-urea breath test (UBT) is commonly used, but it is challenging for certain patients, such as children. In these population, the stool antigen test (SAT) is easier to perform and has shown to be accurate. The SAT is a promising non-invasive option for H. pylori detection. A study assessed the efficacy of a novel SAT, the monoclonal antibody-based automated LIAISON® Meridian H. pylori SA, against the established reference, the UBT. This prospective multicenter study (9 Spanish centers) enrolled patients ≥18 years needing UBT for initial diagnosis of H. pylori infection or confirmation of eradication. The analysis included 307 patients (145 naïve, 162 confirmation of eradication). Using recommended cutoffs (SAT negative < 0.90, positive ≥ 1.10) the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were 67%, 97%, 86%, 92% and 91%, respectively, obtaining an area under the ROC curve (AUC) of 0.85. Some discrepancies existed between SAT and UBT in 28 patients (7 false positives and 21 false negatives). Among the 21 false negatives, 15 had borderline UBT delta value. In 25 discordant samples, PCR targeting H. pylori DNA was performed to re-evaluate positivity and SAT accuracy was re-tested; sensitivity, specificity, PPV, NPV, accuracy and AUC were 94%, 97%, 86%, 99%, 97% and 0.96, respectively. The new LIAISON® Meridian H. pylori SA SAT showed a good accuracy for diagnosis of H. pylori infection.

 

Learning Objectives