Time trends and geographical variation of Helicobacter pylori antibodies in Finland were
investigated by enzyme immunoassay in 20- to 34-year-old randomly selected females from six
localities during 1969–73 (n = 375), and 15- to 45-year-old females representing nine
communities and four geographical areas in 1983 (n = 882) and 1995 (n = 842). In the six
communities investigated at three different time points, the overall prevalence declined from 38
to 12%, with an emphasis on the latter 12 years. The regionally varying rate of decrease in
helicobacter prevalence changed the pre-existing geographical variation, leaving northern
Finland with the highest rate. A 10%-units higher local helicobacter prevalence seemed to
predict a 23% (95% CI 3–44%) higher gastric cancer incidence 20 years later. The overall
decline in helicobacter seropositivity is consistent with earlier reports from Finland and other
developed countries, and supports the cohort theory as an explanation for the age-related
increase in H. pylori seroprevalence.