Long‐term Follow up of Helicobacter pylori IgG Serology After Eradication and Reinfection Rate of H. pylori in South Korea

BACKGROUND: Serology is widely used for epidemiologic research of Helicobacter pylori. However, there is limited information on the long-term follow up of H. pylori titers after eradication. In addition, it is presumed that the reinfection rate decreases as the H. pylori infection rate decreases. The aim of this study was to investigate the long-term follow up of H. pylori IgG, and to evaluate the reinfection rate of H. pylori in Korea. METHODS: Among 247 patients, who were enrolled during 2003-07, 185 patients with invasive H. pylori test positive received proton pump inhibitor-based triple therapy, and follow-up H. pylori testing, including histology, CLOtest, culture, and serology, were evaluated 2, 10, and 18 months after H. pylori eradication. RESULTS: The initial H. pylori IgG optical density (OD(450 nm)), 2.06, gradually decreased to 0.63 (67% reduction) at 18 months after H. pylori eradication. The seroreversion rate was 5, 10, and 45% at 2, 10, and 18 months after H. pylori eradication, respectively. The recrudescence of H. pylori was 3.49%, and the annual reinfection rate was 2.94% per year. H. pylori IgG titers abruptly increased in cases with recrudescence and reinfection, and correlated with the results of the invasive H. pylori tests. CONCLUSION: The results of this study showed that H. pylori IgG serology could be used for the determination of reinfection of H. pylori, but not for the diagnosis of H. pylori eradication. The reinfection rate of H. pylori, in Korea, was found to be very low, 2.94% per year.