Four-year trends in Helicobacter pylori IgG serology following successful eradication

PURPOSE: Detection of anti-Helicobacter-pylori antibodies is accurate in the diagnosis of the infection, and there is a decline in IgG titers after successful eradication. It is not known whether these titers continue to decline during the next 3 to 4 years. PATIENTS AND METHODS: Patients had been successfully treated for H pylori with triple therapy (metronidazole, tetracycline, and bismuth subsalicylate) during 1990 and 1991. Those who had frozen serum samples available from that time were contacted to have follow-up serum collected in 1994. A simultaneous [C-13]urea breath test was done to confirm H pylori infection status. Serology was determined by quantitative enzyme-linked immunosorbent assay (ELISA) and qualitative immunoassay. RESULTS: All 29 patients who agreed to participate were free of H pylori infection. The-ii had a mean decrease in H pylori IgG titers of 51% from baseline (P <0.001). Titers remained stable from 1 year to a mean of 3.5 years after therapy (range 2.5 to 4.4). Of the 29 patients, 21 (72%) remained seropositive by ELISA 3.5 years after successful H pylori treatment, and 18 (62%) remained positive by rapid serum immunoassay. CONCLUSION: IgG titers against N pylori plateau at a 50% decrease after therapy. Helicobacter pylori serology, either quantitative or qualitative, will yield false positive results in patients who have previously been treated for H pylori and should not be used to determine infection status in this population. (C) 1998 by Excerpta Medica, Inc.