Evaluation of whole blood antibody kit to detect active Helicobacter pylori infection.

OBJECTIVES

To evaluate the sensitivity and specificity of a whole blood antibody test (Helisal Rapid Blood test) for the detection of Helicobacter pylori using endoscopic diagnostic criteria of histology and urease tests as the "gold standard."

METHODS

A prospective trial of Helisal Rapid Blood (HRB) test was carried out in patients undergoing investigations for dyspepsia that included endoscopic biopsy for rapid urease test, microbiological culture, and histology. Blood samples were obtained at the time of endoscopy and were tested for the presence of antibody to H. pylori using the HRB test. In a separate patient group, results of antibody tests in whole venous and capillary blood were compared (n = 25).

RESULTS

The rapid blood test was carried out immediately after the endoscopic examination with a result available in under 10 min in all cases. In 203 patients examined, the HRB test detected 70 of 203 to be H. pylori positive as compared with 71 of 203 using urease/histology. Against combined urease/histology tests, the HRB test achieved 82% sensitivity and 91% specificity. Five patients were judged to be "false negative" on endoscopic tests for H. pylori (extensive intestinal metaplasia n = 3; recent use of antimicrobials) yet the HRB test diagnosed the presence of infection, which could be shown to resolve on treatment. The HRB achieved 89% sensitivity and 91% specificity upon correctly including these five patients in the calculations. In all 25 patients tested, venous and capillary blood results concurred giving HRB test positivity in each case.

CONCLUSIONS

Whether using whole venous or capillary blood, the HRB test is a quick, convenient, and accurate test for the diagnosis of active H. pylori infection in patients previously not treated. In a subgroup of patients with low level infection due to recent antimicrobials or intestinal metaplasia negative to all endoscopic tests, the blood test can still correctly diagnose H. pylori infection. Because blood samples require no centrifugation before testing, the greatest usefulness of this test will be that of a primary office diagnostic device.