title: Case definition in epidemiologic studies of AD/HD.
abstract: OBJECTIVE
  Propose a five-step multigating, multimodal procedure for research case definition and identification of attention-deficit/hyperactivity disorder (AD/HD) in population-based epidemiologic studies.
  
  
  METHODS
  Subjects included a birth cohort of all children born between 1976 and 1982 who remained in Rochester after age 5. Screening for AD/HD required 4 steps, using these sources: school/medical records, computerized diagnostic index, and private psychiatry records. In step 5, research criteria were applied to potential cases. The model for defining cases used combinations of three categories of information (DSM-IV, questionnaire, clinical diagnosis). Validity was tested by comparing medication treatment, substance abuse, school outcomes, and comorbidities between cases who did or did not meet DSM-IV criteria.
  
  
  RESULTS
  Among 5718 subjects, 1344 potential cases were identified; 379 met research criteria. No difference in gender, treatment, school outcome, or professional making clinical diagnoses was found between cases who did (N=228) and did not (N=151) meet DSM-IV criteria. However, cases not meeting DSM-IV criteria were more inattentive (33.8% vs. 17.1%; p < 0.001), older (age 12.8 vs. 10.5 years; p=0.01), with less substance abuse (15.2% vs. 26.3%; p < 0.001) and psychiatric comorbidities (43.1% vs. 54.4%; p=0.031).
  
  
  CONCLUSIONS
  If only DSM-IV criteria were applied, 151 cases would not have been identified. This study underscores the importance of using multiple sources and combinations of documented information for case definition and identification.
authors.affiliation: Department of Health Sciences Research, Division of Epidemiology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA. katusic.slavica@mayo.edu
authors.forename: Slavica K
authors.initials: SK
authors.lastname: Katusic
authors.forename: William J
authors.initials: WJ
authors.lastname: Barbaresi
authors.forename: Robert C
authors.initials: RC
authors.lastname: Colligan
authors.forename: Amy L
authors.initials: AL
authors.lastname: Weaver
authors.forename: Cynthia L
authors.initials: CL
authors.lastname: Leibson
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Jacobsen
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000453:epidemiology*; D002648:Child; D015331:Cohort Studies; D039721:Diagnostic and Statistical Manual of Mental Disorders; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening; D008910:Minnesota / Q000453:epidemiology