title: Epidemiology of Helicobacter pylori infection among 4742 randomly selected subjects from Northern Ireland.
abstract: 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.
  
  
  OBJECTIVE
  To examine the distribution and determinants of H. pylori infection in a developed country.
  
  
  METHODS
  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 > or = 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 > or = 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 as a possible risk factor for H. pylori infection.
authors.affiliation: Department of Epidemiology and Public Health, Queen's University of Belfast, Royal Group of Hospitals, Northern Ireland.
authors.forename: L J
authors.initials: LJ
authors.lastname: Murray
authors.forename: E E
authors.initials: EE
authors.lastname: McCrum
authors.forename: A E
authors.initials: AE
authors.lastname: Evans
authors.forename: K B
authors.initials: KB
authors.lastname: Bamford
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000428:Alcohol Drinking; D001827:Body Height; D015992:Body Mass Index; D002648:Child; D005260:Female; D006306:Health Surveys; D016481:Helicobacter Infections / Q000453:epidemiology*; D016480:Helicobacter pylori; D006801:Humans; D008297:Male; D008875:Middle Aged; D009660:Northern Ireland / Q000453:epidemiology; D015995:Prevalence; D011897:Random Allocation; D012307:Risk Factors; D012698:Serologic Tests; D012737:Sex Factors; D012907:Smoking; D012923:Social Class