Stool antigen test for diagnosis of Helicobacter pylori infection in children with symptomatic disease:: A prospective study

Objective: Noninvasive tests for the diagnosis of Helicobacter pylori (Hp) infection in children are limited by low accuracy rates and lack of validation. Existing studies indicate that the stool antigen test (HpSA) has an acceptable level of accuracy for the diagnosis of Hp infection in adults but not children. The aim of this study was to evaluate the accuracy of the HpSA test for the detection of Hp infection in U.S. children. Methods: Children requiring upper endoscopic procedures were prospectively recruited from two pediatric gastroenterology clinics. Stool samples were collected from each participant before endoscopy. The presence of Hp infection was determined by positive histologic findings and positive rapid urease test (RUT). The presence of Hp organisms in stool was determined by an enzyme-linked immunosorbent assay using a commercially available polyclonal antibody kit (Meridian Diagnostics, Cincinnati, OH, U.S.A.). Results of the stool antigen test were compared with histology findings and RUT results. Results: One hundred twenty-one children (mean age, 10.1 +/- 3.7 years) participated, of whom 9 (7.4%) had Hp infection. Histologic findings and RUT results were concordant in 95% of the children. Per study protocol, HpSA had a sensitivity, specificity, positive and negative predictive value, and accuracy rate of 67%, 99%, 86%, 97%, and 96.5%, respectively. Conclusion: HpSA, a polyclonal antibody test, had a low sensitivity for infection in children in the United States and at present cannot replace histologic findings as the gold standard for the diagnosis of Hp infection in the pediatric population.