title: Multilevel analysis of hepatitis A infection in children and adolescents: a household survey in the Northeast and Central-west regions of Brazil.
abstract: BACKGROUND
  The objectives were to estimate the prevalence of hepatitis A among children and adolescents from the Northeast and Midwest regions and the Federal District of Brazil and to identify individual-, household- and area-levels factors associated with hepatitis A infection.
  
  
  METHODS
  This population-based survey was conducted in 2004-2005 and covered individuals aged between 5 and 19 years. A stratified multistage cluster sampling technique with probability proportional to size was used to select 1937 individuals aged between 5 and 19 years living in the Federal capital and in the State capitals of 12 states in the study regions. The sample was stratified according to age (5-9 and 10- to 19-years-old) and capital within each region. Individual- and household-level data were collected by interview at the home of the individual. Variables related to the area were retrieved from census tract data. The outcome was total antibodies to hepatitis A virus detected using commercial EIA. The age distribution of the susceptible population was estimated using a simple catalytic model. The associations between HAV infection and independent variables were assessed using the odds ratio and corrected for the random design effect and sampling weight. Multilevel analysis was performed by GLLAMM using Stata 9.2.
  
  
  RESULTS
  The prevalence of hepatitis A infection in the 5-9 and 10-19 age-group was 41.5 and 57.4%, respectively for the Northeast, 32.3 and 56.0%, respectively for the Midwest and 33.8 and 65.1% for the Federal District. A trend for the prevalence of HAV infection to increase according to age was detected in all sites. By the age of 5, 31.5% of the children had already been infected with HAV in the Northeast region compared with 20.0% in the other sites. By the age of 19 years, seropositivity was approximately 70% in all areas. The curves of susceptible populations differed from one area to another. Multilevel modeling showed that variables relating to different levels of education were associated with HAV infection in all sites.
  
  
  CONCLUSIONS
  The study sites were classified as areas with intermediate endemicity area for hepatitis A infection. Differences in age trends of infection were detected among settings. This multilevel model allowed for quantification of contextual predictors of hepatitis A infection in urban areas.
authors.affiliation: State University of Pernambuco, School of Medical Sciences, Oswaldo Cruz University Hospital, Recife, PE, Brazil. Ricardo.ximenes@pq.cnpq.br
authors.forename: Ricardo Arraes
authors.initials: RA
authors.lastname: de Alencar Ximenes
authors.forename: Celina Maria Turchi
authors.initials: CM
authors.lastname: Martelli
authors.forename: Edgar
authors.initials: E
authors.lastname: Merchán-Hamann
authors.forename: Ulisses Ramos
authors.initials: UR
authors.lastname: Montarroyos
authors.forename: Maria Cynthia
authors.initials: MC
authors.lastname: Braga
authors.forename: Maria Luíza Carvalho
authors.initials: ML
authors.lastname: de Lima
authors.forename: Maria Regina Alves
authors.initials: MR
authors.lastname: Cardoso
authors.forename: Marília Dalva
authors.initials: MD
authors.lastname: Turchi
authors.forename: Marcelo Abrahão
authors.initials: MA
authors.lastname: Costa
authors.forename: Luiz Cláudio Arraes
authors.initials: LC
authors.lastname: de Alencar
authors.forename: Regina Célia
authors.initials: RC
authors.lastname: Moreira
authors.forename: Gerusa Maria
authors.initials: GM
authors.lastname: Figueiredo
authors.forename: Leila Maria Moreira Beltrão
authors.initials: LM
authors.lastname: Pereira
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D004522:Educational Status; D005260:Female; D006306:Health Surveys; D006506:Hepatitis A / Q000453:epidemiology*; D017957:Hepatitis A Virus, Human; D006801:Humans; D008297:Male; D055361:Multilevel Analysis; D011203:Poverty; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology*; D015995:Prevalence; D014505:Urban Population; D055815:Young Adult