Comparison of commercial diagnostic tests for Helicobacter pylori antibodies.

A number of serological tests measuring the presence of Helicobacter pylori-specific serum immunoglobulin G (IgG) are now commercially available. The aim of this study was to evaluate the clinical accuracy of five commercial H. pylori antibody tests: GAP-IgG (Biomerica), HELpTEST (AMRAD, Kew, Victoria, Australia), HELICO-G (Porton Cambridge), Pyloriset (Orion Diagnostica), and ROCHE (Roche Diagnostics). A total of 162 subjects presenting for routine upper endoscopy were studied. H. pylori was diagnosed if culture, histology, or both were positive. Ten milliliters of venous blood was collected at the time of endoscopy for serological assessment. The sensitivity and specificity of each test (GAP-IgG, HELpTEST, HELICO-G, Pyloriset, and ROCHE) were as follows: 83 and 79%, 92 and 77%, 86 and 65%, 89 and 56%, and 98 and 69%, respectively. Positive and negative predictive values were 97 and 83%, 90 and 91%, 76 and 83%, 68 and 84%, and 86 and 97%, respectively. The specificity of most tests increased by approximately 10% when sera from subjects less than 45 years old were examined. The number of sera falling into the grey zone for each test (an indeterminate result with respect to H. pylori status) varied between 2.5 and 19%. This study highlights the need for all serological kits to be independently evaluated on the population to be studied by testing against a microbiologically defined panel of H. pylori-positive and -negative sera.