Stool antigen tests in the diagnosis of Helicobacter pylori infection before and after eradication therapy

Aim: To evaluate two enzyme immunoassay-based stool antigen tests, Premier Platinum HpSA and Amplified IDEIA HpStAR, and one rapid test, ImmunoCard STAT! HpSA, in the primary diagnosis of Helicobacter pylori (H pylori) infection and after eradication therapy.METHODS: Altogether 1 574 adult subjects were screened with a whole-blood H pylori antibody test and positive results were confirmed with locally validated serology and 13C-urea breath test. All 185 subjects,confirmed to be H pylori positive, and 97 H pylorinegative individuals, randomly selected from the screened study population and with negative results in serology and UBT, were enrolled. After eradication therapy the results of 182 subjects were assessed.RESULTS: At baseline, the sensitivity of HpSA and HpStAR was 91.9% and 96.2%, respectively, and specificity was 95.9% for both tests. ImmunoCard had sensitivity of 93.0% but specificity of only 88.7%. After eradication therapy, HpSA and HpStAR had sernsitivity of 81.3% and 100%, and specificity of 97.0% and 97.6%,respectively. ImmunoCard had sensitivity of 93.8% and specificity of 97.0%. HpSA, HpStAR, and ImmunoCard had PPV 77%, 80%, and 75%, and NPV 98%, 100%,and 99%, respectively.CONCLUSION: In primary diagnosis, the EIA-based tests performed well. After eradication therapy, negative results were highly accurate for all the three tests.HpStAR had the best overall performance.