Value of quantitative serology for confirmation of Helicobacter pylori eradication: an 18-month follow-up study.

In this study several therapies were administered to 124 H. pylori-positive patients and IgG antibody titers were measured by ELISA at months 0, 2, 3, 6, 12, and 18 months. Serum titers of IgG antibody progressively decreased after H. pylori eradication; at 3 months, the area under the receiver operating characteristic curve for the decrease of IgG antibody titers for confirming H. pylori eradication was 0.99, with 100% sensitivity and 99% specificity (when the cutoff point was set at 3 U/mL). We conclude that a decrease in serum titers of IgG antibody to H. pylori relatively early after completion of therapy (1 month after ranitidine or bismuth therapy is completed and 2.5 months after antibiotic therapy is completed) can be used as a noninvasive, simple, and inexpensive method to confirm H. pylori eradication.