Declining trends in prevalence of Helicobacter pylori infection by birth‐year in a Japanese population

Gastric cancer incidence and mortality have been decreasing in Japan. These decreases are likely due to a decrease in prevalence of Helicobacter pylori infection. Our aim was to characterize the trends in prevalence of H. pylori infection focused on birth‐year. We carried out a cross‐sectional study that included 4285 subjects who were born from 1926 to 1989. We defined H. pylori infection by the serum H. pylori antibody titer. Individuals having H. pylori infection and those with negative H. pylori antibody titer and positive pepsinogen test were defined as high‐risk individuals for gastric cancer. We estimated the birth‐year percent change (BPC) of the prevalence by Joinpoint regression analysis. The prevalence of H. pylori infection among the subjects born from 1927 to 1949 decreased from 54.0% to 42.0% with a BPC of −1.2%. It was followed by a rapid decline in those born between 1949 (42.0%) and 1961 (24.0%) with a BPC of −4.5%, which was followed by those born between 1961 (24.0%) and 1988 (14.0%) with a BPC of −2.1%. The proportion of high‐risk individuals for gastric cancer among the subjects born from 1927 to 1942 decreased from 62.0% to 55.0% with a BPC of −0.8%. A subsequent rapid declining trend was observed in those born between 1942 (55.0%) and 1972 (18.0%) with a BPC of −3.6%, and then it became stable. These remarkable declining trends in the prevalence of H. pylori infection by birth‐year would be useful to predict the future trend in gastric cancer incidence in Japan.