Increased risk of Helicobacter pylori associated with birth in wartime and post-war Japan.

BACKGROUND Helicobacter pylori infection is now widely recognized as a cause of stomach cancer. We assessed trends in H. pylori infection in Japan, a population with high rates of gastric malignancy. METHODS Using an enzyme-linked immunosorbent assay (ELISA), we tested sera collected between 1980 and 1993 from Tokyo University Hospital patients for anti-H. pylori IgG. Patients ranged in age from 0 to 94 years. Helicobacter pylori prevalence was then assessed for age and/or birth cohort effects. RESULTS Of 1207 sera, 470 (38.9%) were positive for H. pylori IgG. By univariate analysis, both older age and birth in an earlier decade were associated with an increased risk of infection. Age-specific prevalence of H. pylori by birth cohort suggested increases in infection during the decades from 1900 to 1959, and age-specific decreases since 1960. In multivariate analysis, H. pylori infection increased with age and was most prevalent among those born in the 1940s and 1950s. CONCLUSION Relative to other birth cohorts, people born in the 1940s and 1950s have a higher prevalence of H. pylori. This increased prevalence of infection among those born in wartime Japan likely attests to the impact of compromised living conditions on acquisition of H. pylori, and may portend continued high rates of gastric cancer in forthcoming years.