title: Estimating adjusted prevalence ratio in clustered cross-sectional epidemiological data.
abstract: BACKGROUND
  Many epidemiologic studies report the odds ratio as a measure of association for cross-sectional studies with common outcomes. In such cases, the prevalence ratios may not be inferred from the estimated odds ratios. This paper overviews the most commonly used procedures to obtain adjusted prevalence ratios and extends the discussion to the analysis of clustered cross-sectional studies.
  
  
  METHODS
  Prevalence ratios(PR) were estimated using logistic models with random effects. Their 95% confidence intervals were obtained using delta method and clustered bootstrap. The performance of these approaches was evaluated through simulation studies. Using data from two studies with health-related outcomes in children, we discuss the interpretation of the measures of association and their implications.
  
  
  RESULTS
  The results from data analysis highlighted major differences between estimated OR and PR. Results from simulation studies indicate an improved performance of delta method compared to bootstrap when there are small number of clusters.
  
  
  CONCLUSIONS
  We recommend the use of logistic model with random effects for analysis of clustered data. The choice of method to estimate confidence intervals for PR (delta or bootstrap method) should be based on study design.
authors.affiliation: State University of Feira de Santana, Feira de Santana, Brazil. carlosateles@yahoo.com.br
authors.forename: Carlos Antônio S T
authors.initials: CA
authors.lastname: Santos
authors.forename: Rosemeire L
authors.initials: RL
authors.lastname: Fiaccone
authors.forename: Nelson F
authors.initials: NF
authors.lastname: Oliveira
authors.forename: Sérgio
authors.initials: S
authors.lastname: Cunha
authors.forename: Maurício L
authors.initials: ML
authors.lastname: Barreto
authors.forename: Maria Beatriz B
authors.initials: MB
authors.lastname: do Carmo
authors.forename: Ana-Lucia
authors.initials: AL
authors.lastname: Moncayo
authors.forename: Laura C
authors.initials: LC
authors.lastname: Rodrigues
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Cooper
authors.forename: Leila D
authors.initials: LD
authors.lastname: Amorim
mesh_terms: D002648:Child; D016000:Cluster Analysis; D003198:Computer Simulation; D003430:Cross-Sectional Studies; D016021:Epidemiologic Studies; D006801:Humans; D016015:Logistic Models; D016017:Odds Ratio; D015995:Prevalence