Usefulness of serological IgG antibody determinations for confirming eradication of Helicobacter pylori infection

OBJECTIVE: Prior studies have suggested that IgG antibody titers may be use ful to confirm successful treatment of Helicobacter pylori (H. pylori) infe ction. However, the diagnostic value of decreasing IgG titers is limited by the necessity to perform pre and posttreatment tests in parallel which req uires stored sera. Our objective was to assess the accuracy of IgG antibody titers using the HM-CAP IgG EIA kit (Enteric Products) in monitoring treat ment of H. pylori infection and to compare the relative accuracy of paralle l versus serial determinations. METHODS: The C-14 urea breath test (UBT) was used to confirm H. pylori infe ction in 83 dyspeptic patients and eradication of the organism at 4 wk and 6 months posttreatment. IgG titers pretherapy and 6 months posttherapy were determined either serially (separate EIA plates) or in parallel (same ELA plate), and the relative percent decline in antibody titer was calculated. RESULTS: When a decline of greater than or equal to 25% at 6 months was use d as the cut-off for H. pylori eradication, mean sensitivities of serial an d parallel determinations were 87.5% and 86.8%, respectively, and mean spec ificities of both were 100%. In 68 of 75 patients in whom the organism was eradicated, the mean decrease in IgG titer at 6 months was 41.1% for serial determinations and 41.5% for parallel determinations. CONCLUSIONS: Serial or parallel IgG titers offer equivalent diagnostic accu racy for confirming H. pylori eradication after therapy. A greater than or equal to 25% decline in titer 6 months after therapy is a sensitive and spe cific marker for eradication of the infection. Serial evaluation of IgG tit ers does not require serum storage, and is a cost-effective and accurate al ternative to the UBT or endoscopy-based methods. (Am J Gastroenterol 1999;9 4:2105-2108. (C) 1999 by Am. Coll. of Gastroenterology).