Helicobacter pylori stool antigen test: clinical evaluation and cost analysis of a new enzyme immunoassay.

Noninvasive tests for Helicobacter pylori are increasingly used. Recently, an enzyme immunoassay for H. pylori detection in feces has been put on the market. Aim of this multicenter study was to evaluate the usefulness of this novel test as a predictor of H. pylori status in the pretreatment setting. Three hundred consecutive patients were enrolled. None of the patients had received any eradicating treatment in the last 12 months, and all underwent gastroscopy with biopsies of the antrum and body for histology (H) and rapid urease test (RUT). H. pylori status was defined positive (or negative) if both H and RUT were positive (or negative). When H and RUT gave conflicting results, the patients were classified as H. pylori-indeterminate. A stool specimen was collected for each patient and tested by using a novel enzyme immunoassay for H. pylori detection (HpSAT). Sensitivity, specificity, and diagnostic accuracy of the test were calculated, as was the cost of each assay. H. pylori status was positive in 159 patients, negative in 131, and indeterminate in 10. HpSAT gave evaluable results (positive or negative) in 293 patients, and doubtful results in 7 (2.3%). Sensitivity, specificity, and diagnostic accuracy of HpSAT were 96.8%, 89.7%, and 93.6% respectively. Considering the H. pylori-indeterminate patients as positive, the percentages were 95.8%, 98.7%, and 93.2% respectively. The cost for each assay was about US $27. These results suggest that HpSAT is a noninvasive, simple, reliable, fast, and cheap method for evaluating H. pylori status in the pretreatment setting.