Serological diagnosis of Helicobacter pylori--evaluation of four tests in the presence or absence of non-steroidal anti-inflammatory drugs.

The host's humoral immune response to Helicobacter pylori has been used in the diagnosis of active infection with these organisms. Several commercial tests are available but there are few and unconfirmed reports of their efficacy. This study aimed to assess and compare the efficacy of the following H pylori serological tests in patients treated or not treated with non-steroidal anti-inflammatory drugs (NSAID): Pyloriset Latex, Helico-G, Biolab Malakit, and Bio-Rad GAP Test IgG. Venous blood was tested at random in 124 patients, 64 of whom had received NSAID and 60 who had not. H pylori IgG antibodies were detected by latex agglutination (Pyloriset), or by ELISA (the remaining tests). Endoscopic gastric antral biopsy specimens were also obtained for urease activity, culture, and histology. Detection of H pylori by at least two of these was considered as a true positive, and its absence in all biopsy specimens as a true negative. The sensitivity values in the presence (or absence) of NSAID were: Pyloriset Latex, 59 (60)%; Helico-G, 79 (74)%; Biolab Malakit, 85 (81)%; and Bio-Rad GAP Test IgG, 100 (95)%. The respective specificity values were: 50 (71)%, 47 (59)%, 50 (65)%, and 30 (29)%. The Bio-Rad GAP Test IgG has the highest sensitivity and the lowest specificity values regardless of NSAID intake. The sensitivity of the other tests, however, is less than that of the standard biopsy related tests and their specificity is even lower in chronic NSAID users.