Performance evaluation of a rapid whole-blood immunoassay for the detection of IgG antibodies against Helicobacter pylori in daily clinical practice.

Background: A growing number of rapid Helicobacter pylori antibody tests are commercially available now, however, some of these tests are often used without sufficient evaluation. The aim of this study was to evaluate the performance of a commercially available rapid whole-blood immunoassay (gabControl(®) H. pylori; gabmed GmbH, Köln, Germany), for the qualitative detection of IgG antibodies against H. pylori with the (13)C-urea breath test ((13)C-UBT) serving as a reference method.
Methods: A total of 108 consecutive outpatients, who were referred for (13)C-UBT by general practitioners and specialists, were also tested for H. pylori infection by the gabControl(®) H. pylori immunoassay. The clinical performance of this rapid whole-blood test was evaluated by determining the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) compared to the (13)C-UBT. The agreement between the two tests was calculated using Cohen's Kappa (κ) with 95 % confidence intervals (CI).
Results: The agreement between the gabControl(®) H. pylori assay and the (13)C-UBT was 0.62 [95 % confidence intervals (CIs) 0.47-0.76; P < 0.001]. With the (13)C-UBT serving as the non-invasive gold standard method of H. pylori diagnosis, the gabControl(®) H. pylori assay demonstrated a sensitivity and specificity of 91.4 and 76.7 %, respectively, with a PPV of 65.3 % and a NPV of 94.9 %. Seventeen (15.7 %) individuals with a positive H. pylori anamnesis showed a negative (13)C-UBT and were typed positive by the gabControl(®) H. pylori assay. Of these, 13 (76.5 %) and 3 individuals (17.6 %) had completed one and two eradication therapies, respectively.
Conclusions: The gabControl(®) H. pylori immunoassay is a rapid and easy to use first line screening tool for H. pylori IgG antibody detection in daily clinical practice. However, this assay should not be used for confirmation of the successful H. pylori eradication after antibiotic treatment.