Epidemiology of Helicobacter pylori infection among 4742 randomly selected subjects from Northern Ireland

Background. Despite the widespread prevalence and serious clinical sequelae of infection with Helicobacter pylori, there have been few large population-based studies, using randomly selected subjects, examining the epidemiology of this infection. Aim. To examine the distribution and determinants of H. pylon infection in a developed country. Subjects and Setting. Overall 4742 subjects, aged 12-64, from Northern ireland were randomly selected. Methods. Helicobacter pylori specific IgG antibodies were measured by enzyme linked immunosorbent assay, using an acid-glycine extract antigen, in stored serum from subjects who had participated in three linked population-based surveys of cardiovascular risk factors performed in 1986 and 1987. Results. The overall prevalence of H. pylori infection was 50.5%. Prevalence increased with age from 23.4% in 12-14 year olds to 72.7% in 60-64 year olds: chi(2) for trend 518, P < 10(-4). In subjects aged greater than or equal to 25, infection was more common in males (60.9%) than females (55.2%):;chi(2) = 9.53, P < 0.01. This relation remained significant after adjusting for age, and measures of socioeconomic class: odds ratio (OR) for infection, male versus female was 1.19 (95% confidence interval [CI] : 1.02-1.40). infection was associated with social class: the adjusted OR of infection in subjects from manual social classes relative to those from non-manual classes was 1.7 (95% Ci : 1.47-1.98). Infection was significantly more common in current smokers and ex-smokers than in subjects who had never smoked: adjusted OR for infection, ex-smokers versus never smoked was 1.22 (95% CI : 1.01-1.49); for smokers of greater than or equal to 20/day versus never smoked OR = 1.33 (95% CI:1.05-1.67). Infection was not associated with height in adult males but mean height in infected women was lower than in uninfected women after adjusting for age and socioeconomic status: difference in mean height (SE), -0.85 cm (0.32), P < 0.01. There was no demonstrable relationship between H. pylori infection and current alcohol intake. Conclusions. This study demonstrated a high prevalence of infection in a population from a developed country. Previously reported associations between H. pylori infection, age, sex, social class, and reduced height in females were confirmed and smoking was identified asa possible risk factor for H. pylori infection.