Long-term response of Helicobacter pylori antibody titer after eradication treatment in middle-aged Japanese: JPHC-NEXT Study.

BACKGROUND Helicobacter pylori (H. pylori) is an established causative factor of gastric cancer. Although the expansion of insurance coverage has led to an increase in the number of patients treated for H. pylori, the population impact of eradication treatment for H.pylori has been scarcely investigated. This study aimed to clarify the long-term responses of H. pylori antibody titer after eradication treatment using large scale cross-sectional data from the Japan Public Health Center-based Prospective Study for the Next Generation (JPHC-NEXT Study). METHODS A total of 55,282 Japanese participants aged 40 to 74 years residing in 16 areas provided blood samples between 2011 and 2016. From these, treated (n=6,276) and untreated subjects who were seropositive for H. pylori or had serological atrophy (n= 22,420) formed the study population (n=28,696). Seropositivity was defined as an anti-H. pylori IgG titer of ≥10 U/mL. Antibody level was compared among subjects according to self-reported treatment history as untreated, and treated for less than one year (<1Y), one to five years (1-5Y), and more than six years ago (6Y+). RESULTS Median serum antibody titer was 34.0 U/mL, 7.9 U/mL, 4.0 U/mL, and 2.9 U/mL for the Untreated, <1Y, 1-5Y, and 6Y+ groups, respectively. While those treated for H.pylori within the previous year had a 76.8% lower antibody titer compared to untreated subjects, approximately 41% of subjects were still seropositive. CONCLUSIONS A significant reduction in H.pylori antibody titer occurs within one year after eradication treatment, but that a long period is needed to achieve complete negative conversion.