title: ADHD in a representative sample of the Brazilian population: estimated prevalence and comparative adequacy of criteria between adolescents and adults according to the item response theory.
abstract: BACKGROUND
  Attention deficit hyperactivity disorder (ADHD) is a clinically significant disorder in adulthood, but current diagnostic criteria and instruments do not seem to adequately capture the complexity of the disorder in this developmental phase. Accordingly, there are limited data on the proportion of adults affected by the disorder, specially in developing countries.
  
  
  METHODS
  We assessed a representative household sample of the Brazilian population for ADHD with the Adult ADHD Self-report Scale (ASRS) Screener, and evaluated the instrument according to the Rasch model of item response theory.
  
  
  RESULTS
  The sample was comprised by 3007 individuals, and the overal prevalence of positive screeners for ADHD was 5.8% [95% confidence interval (CI), 4.8-7.0]. Rasch analyses revealed the misfitt of the overall sample to expectations of the model. The evaluation of the sample stratified by age revealed that data for adolescents showed a signficant fittnes to the model expectations, while items completed by adults were not adequated.
  
  
  CONCLUSIONS
  The lack of fitness to the model for adult respondents challenges the possibility of a linear transformation of the ordinal data into interval measures and the utilization of parametric analyses of data. This result suggests that diagnostic criteria and instruments for adult ADHD must take into account a developmental perspective. Moreover, it calls for further evaluation of currently employed research methods in light of modern theories of psychometrics.
authors.affiliation: Department of Psychiatry, University of São Paulo Medical School, Brazil.
authors.forename: Guilherme
authors.initials: G
authors.lastname: Polanczyk
authors.forename: Ronaldo
authors.initials: R
authors.lastname: Laranjeira
authors.forename: Marcos
authors.initials: M
authors.lastname: Zaleski
authors.forename: Ilana
authors.initials: I
authors.lastname: Pinsky
authors.forename: Raul
authors.initials: R
authors.lastname: Caetano
authors.forename: Luis Augusto
authors.initials: LA
authors.lastname: Rohde
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis* / Q000453:epidemiology*; D001938:Brazil / Q000453:epidemiology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods / Q000706:statistics & numerical data*; D015995:Prevalence; D011594:Psychometrics / Q000706:statistics & numerical data; D011795:Surveys and Questionnaires; D055815:Young Adult