title: Prevalence, incidence and risk factors for Helicobacter pylori infection in a cohort of Portuguese adolescents (EpiTeen).
abstract: BACKGROUND
  Helicobacter pylori infection is acquired mainly during childhood, but it may occur throughout life. Understanding the determinants of infection at different ages is essential to clarify dynamics of H. pylori related diseases and to design preventive strategies.
  
  
  OBJECTIVE
  To estimate the prevalence of H. pylori infection at the age of 13 and the incidence after a 3-year follow-up and to identify risk factors for infection.
  
  
  METHODS
  Adolescents born in 1990 were recruited in schools from Porto. Whole-cell anti-H. pylori IgG antibodies were quantified by ELISA. Prevalence ratios (PR) and incidence rate ratios (RR) adjusted for parental education were computed at baseline (n = 1312) and at follow-up (n = 280).
  
  
  RESULTS
  The prevalence was 66.2%, lower in subjects with more educated parents (PR = 0.72, 95%CI: 0.63-0.82), and higher for those having more than one sibling (PR = 1.10, 95%CI: 1.02-1.19) and for smokers (PR = 1.11, 95%CI: 1.02-1.20). The incidence was 4.1/100 person-years. Smoking (RR = 2.35, 95%CI: 1.16-4.75) and type of school (RR = 0.38, 95%CI: 0.16-0.95) were associated with the incidence of infection.
  
  
  CONCLUSIONS
  Prevalence and incidence of H. pylori infection were high, suggesting that gastric cancer will remain an important public health problem in this generation of Portuguese. We identified smoking as a modifiable risk factor for infection.
authors.affiliation: Department of Clinical Epidemiology, Predictive Medicine and Public Health, University of Porto Medical School, Porto, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Bastos
authors.forename: Bárbara
authors.initials: B
authors.lastname: Peleteiro
authors.forename: Hugo
authors.initials: H
authors.lastname: Pinto
authors.forename: Ana
authors.initials: A
authors.lastname: Marinho
authors.forename: João T
authors.initials: JT
authors.lastname: Guimarães
authors.forename: Elisabete
authors.initials: E
authors.lastname: Ramos
authors.forename: Carlo
authors.initials: C
authors.lastname: La Vecchia
authors.forename: Henrique
authors.initials: H
authors.lastname: Barros
authors.forename: Nuno
authors.initials: N
authors.lastname: Lunet
mesh_terms: D000293:Adolescent; D003441:Crowding; D004522:Educational Status; D005191:Family Characteristics; D016481:Helicobacter Infections / Q000097:blood / Q000453:epidemiology* / Q000382:microbiology; D016480:Helicobacter pylori / Q000276:immunology; D006801:Humans; D007136:Immunoglobulins / Q000097:blood; D015994:Incidence; D010290:Parents; D011174:Portugal / Q000453:epidemiology; D015995:Prevalence; D012111:Residence Characteristics; D012307:Risk Factors; D012574:Schools; D012907:Smoking / Q000453:epidemiology*
chemical_list: D007136:Immunoglobulins