Performance of Two Immunosorbent Assay Kits for the Detection of Serum Immunoglobulin G to Helicobacter pylori in Untreated Greek Patients

Abstract

Background: The performance of serological methods used to detect Helicobacter pylori varies with the ethnicity and prevalence of the infection in the community. We have prospectively evaluated the performance of two commercially available serum enzyme immunoassays (EIA) detecting H. pylori immunoglobulin G (IgG) antibodies in the sera of untreated Greek patients. Methods: One-hundred-and-thirty consecutive untreated dyspeptic patients underwent endoscopy with biopsies from the gastric body ( n = 2) and antrum ( n = 2). Serum samples were also obtained from each patient. Serum H. pylori IgG antibody titres were determined with two EIA kits (Pyloriset EIA-G and Milenia H. pylori IgG). Sensitivities, specificities and optimal cut-off values of serum EIAs were determined for the population under investigation by using receiver operating characteristic (ROC) curve analysis and histology as gold standard. Results: Ninety-seven patients were defined H. pylori -positive and 33 negative by histology. ROC curve analysis for the Pyloriset kit yielded 86% (95% CI, 78%-92%) sensitivity and 85% (68%-95%) specificity at an optimal cut-off value of S 358 units/ml. The respective values for the Milenia kit were 86% (78%-92%) and 82% (65%-93%) at an optimal cut-off value of S 51 units/ml. The suggested cut-off values of the manufacturers for Pyloriset and Milenia kits are S 300 and S 44 EIA units, respectively, which yield 2% and 4% higher sensitivity, but 9% lower specificity for both EIA kits. Conclusions: Both serum EIA kits performed well in our study. Our data show that EIA cut-off values should be optimized for the population under investigation.