title: The effect of misclassification error on risk estimation in case-control studies.
abstract: BACKGROUND
  In epidemiological studies, misclassification error, especially differential misclassification, has serious implications.
  
  
  OBJECTIVE
  To illustrate how differential misclassification error (DME) and non-differential misclassification error (NDME) occur in a case-control design and to describe the trends in DME and NDME.
  
  
  METHODS
  Different sensitivity levels, specificity levels, prevalence rates and odds ratios were simulated. Interaction graphics were constructed to study bias in the different settings, and the effect of the different factors on bias was described using linear models.
  
  
  RESULTS
  One hundred per cent of the biases caused by NDME were negative. DME biased the association positively more often than it did negatively (70 versus 30%), increasing or decreasing the OR estimate towards the null hypothesis.
  
  
  CONCLUSIONS
  The effect of the sensitivity and specificity in classifying exposure, the prevalence of exposure in controls and true OR differed between positive and negative biases. The use of valid exposure classification instruments with high sensitivity and high specificity is recommended to mitigate this type of bias.
authors.affiliation: Infection and Cancer Group, School of Medicine, Universidad de Antioquia, Medellín, Colombia.
authors.forename: Armando
authors.initials: A
authors.lastname: Baena
authors.affiliation: Epidemiology Group, National School of Public Health, Universidad de Antioquia, Medellín, Colombia.
authors.forename: Isabel Cristina
authors.initials: IC
authors.lastname: Garcés-Palacio
authors.affiliation: Demography and Health Group, National School of Public Health, Universidad de Antioquia, Medellín, Colombia.
authors.forename: Hugo
authors.initials: H
authors.lastname: Grisales
mesh_terms: D015982:Bias; D016022:Case-Control Studies; D003198:Computer Simulation; D016017:Odds Ratio