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

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. 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, (13)C-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. 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 (13)C-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. 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.