Prospective evaluation of a new stool antigen test for the detection of Helicobacter pylori, in comparison with histology, rapid urease test, (13)C-urea breath test, and serology

Background and Aims: This study aimed to evaluate the efficacy of a new polyclonal enzyme immunoassay for the detection of Helicobacter pylori (H. pylori) antigen in stool by determination of the optimal cut‐off value in the screening population. Methods: A consecutive 515 patients undergoing a routine health check‐up were prospectively enrolled. H. pylori infection was defined if at least two of four tests (histology, rapid urease test, ¹³C‐urea breath test, and serology) were positive. A stool antigen test (EZ‐STEP H. pylori) was performed for the detection of H. pylori. The optimal cut‐off value was determined by the receiver–operator characteristic curve. The diagnostic performance of each test was evaluated with regard to the histological diagnosis of atrophic gastritis (AG)/intestinal metaplasia (IM), degree of AG/IM, and old age. Results: Sensitivity, specificity, positive and negative predictive values, and accuracy of the stool antigen test were 93.1%, 94.6%, 95.1%, 92.3%, and 93.8%, respectively. The sensitivity of histology, rapid urease test, and the ¹³C‐urea breath test ranged from 89.1% to 97.6%, and their specificity was > 98%, while serology had high sensitivity, but low specificity. The accuracy of the stool antigen test was comparable to that of other methods (93.6–95.9%), whereas it was higher than that of serology. The stool antigen test still showed good diagnostic performance in the setting of progression of AG/IM and in patients over 40 years. Conclusions: The performance of a new stool antigen test was comparable to that of other methods in the diagnosis of H. pylori infection for the screening population, even with the presence of AG/IM.