LAUSR

Abstract Background Helicobacter pylori infection, chronic gastritis (CG) and atrophic gastritis (AG) are a continuum of consecutive events in the stomach mucosa. We studied the birth cohort and age group-specific prevalence rates of ‘healthy’ (N) and ‘diseased’ stomachs with CG or AG in endoscopic biopsies in adult people born in Finland in 1890–1977. Materials and methods Study series consisted of 690 and 1608 adults with a diagnostic gastroscopy in 1972–1997. All subjects were divided to 10-year age groups and birth cohorts. Based on biopsy histology, relative frequencies (prevalences) of N, CG and AG were estimated by the observed number of cases with N, CG and AG in each study category. Results Prevalence rate of a histologically ‘diseased’ stomach (CG or AG) decreased and that of ‘healthy’ stomach (N) increased, cohort-by-cohort, from 1900 onward by rate 9–12% per every 10-year period in the two study subpopulations, respectively. Prevalences of CG remained unchanged over study groups when N, CG and AG were noted concurrently. By noting ‘diseased’ stomachs only, the prevalence rate of AG increased, and that of CG decreased with age, at rate 9–13% per every 10 years of calendar age. Conclusions Over 70-year period from 1900 onward, the prevalence rate of ‘diseased’ stomach (CG or AG) decreased and that of ‘healthy’ (N) stomach increased in birth cohorts over 50%, by rate about 10% over every 10-year period of time. In birth cohorts, CG progressed to AG with aging of the subjects at a rate of about 10% over every 10 years of calendar age.