Helicobacter pylori Stool Antigen Test (Clinical Evaluation and Cost Analysis of a New Enzyme Immunoassay)

Noninvasive tests for Helicobacter pylori areincreasingly used. Recently, an enzyme immunoassay forH. 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 apredictor of H. pylori status in the pretreatmentsetting. Three hundred consecutive patients wereenrolled. None of the patients had received anyeradicating treatment in the last 12 months, and all underwentgastroscopy with biopsies of the antrum and body forhistology (H) and rapid urease test (RUT). H. pyloristatus was defined positive (or negative) if both H and RUT were positive (or negative). When H and RUTgave conflicting results, the patients were classifiedas H. pylori indeterminate. A stool specimen wascollected for each patient and tested by using a novel enzyme immunoassay for H. pylori detection(HpSAT). Sensitivity, specificity, and diagnosticaccuracy of the test were calculated, as was the cost ofeach assay. H. pylori status was positive in 159patients, negative in 131, and indeterminate in 10. HpSATgave evaluable results (positive or negative) in 293patients, 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 aspositive, 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 anoninvasive, simple, reliable, fast, and cheap methodfor evaluating H. pylori status in the pretreatmentsetting.