Seroprevalence of Helicobacter pylori in a birth cohort of 21-year-old New Zealanders

Objective: To determine the seroprevalence of Helicobacter pylori (H. pylori) in a subset of a birth cohort of New Zealanders at age 21 and examine the association with risk factors and digestion-related symptoms. Design: Assay of serum collected from members of a longitudinal study during 1993-94 and a survey of risk factors and digestion-related symptoms by interview and questionnaire. Methods: Serum from 785 sample members (413 males, 372 females) of the 950 participating in the Dunedin Multidisciplinary Health and Development Study (DMHDS) at age 21 was analysed for H. pylori antibodies. Serum samples (n=579) from the cohort at age 11 collected in 1983 were analysed for those who were seropositive at age 21. Results :The seroprevalence of H. pylori at age 21 was 4.1% (32/785), with proportionally more males in the seropositive group (chi(2)=6.7, P<0.01). Serum samples taken at age 11 were available for 19 of the seropositive group and 74% of these (11 males, three females) were seropositive. The seropositive group at age 21 was no different in the size of their families, but at age 5 contained proportionally more individuals from families of low socioeconomic status (SES) (chi(2)=6.1, P<0.05). There was no difference between the two groups in terms of upper gastrointestinal tract symptoms, recent use oi medications, smoking or alcohol consumption. Conclusion: The seroprevalence of H. pylori among a birth cohort of 21-year-old New Zealanders is significantly lower than among most populations of about the same age in other countries. Seropositivity is higher in males and among families of lower SES, and is not associated with digestion-related symptoms. The seroconversion rate after age 11 appears to be low.