Background: Serology is a good alternative, minimally invasive, diagnostic and screening test for Helicobacter pylori infection. Several immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) commercial kits have been evaluated. Information on IgA ELISAs is relatively poor, and on the combined use of IgG and IgA ELISAs very scarce.
Objective: We intended to evaluate the sensitivity, specificity and predictive values of two quantitative commercial IgG and IgA ELISAs (Helico-G and GAP, respectively) and more particularly the accuracy of their combined use.
Patients and methods: Serum samples and gastric biopsy specimen culture findings from 400 patients were evaluated.
Results: The sensitivity, specificity, positive and negative predictive values of the IgG ELISA Helico-G test in detecting IgG antibodies to H. pylori were 97.2, 85.4, 98.3 and 77.8%, respectively, when compared with those of the reference method used. The corresponding findings for detection of IgA antibodies with the GAP test were 96.4, 80.5, 97.7 and 71.1%, respectively. When considering a patient infected with H. pylori when both tests were positive, the sensitivity, specificity, positive and negative predictive values were 94.1, 85.3, 98.2 and 62.5%, respectively. On the other hand, when at least one test was positive, the corresponding values were 99, 80, 97 and 94%, respectively.
Conclusion: The IgG ELISA Helico-G and IgA ELISA GAP, taken separately, are good and reliable tests for the detection of antibodies to H. pylori. Furthermore, the combined use of both serological methods provided more useful information compared with single IgG and IgA determinations.