title: Validation of the diagnosis of autism in general practitioner records.
abstract: BACKGROUND
  We report on the validity of the computerized diagnoses of autism in a large case-control study investigating the possible association between autism and the measles, mumps and rubella vaccine in the UK using the General Practitioner Research Database (GPRD). We examined anonymized copies of all relevant available clinical reports, including general practitioners' (GP) notes, consultant, speech therapy and educational psychologists reports, on 318 subjects born between 1973 and 1997 with a diagnosis of autism or a related disorder recorded in their electronic general practice record.
  
  
  METHODS
  Data were abstracted to a case validation form allowing for the identification of developmental symptoms relevant to the diagnosis of pervasive developmental disorders (PDDs). Information on other background clinical and familial features was also abstracted. A subset of 50 notes was coded independently by 2 raters to derive reliability estimates for key clinical characteristics.
  
  
  RESULTS
  For 294 subjects (92.5%) the diagnosis of PDD was confirmed after review of the records. Of these, 180 subjects (61.2%) fulfilled criteria for autistic disorder. The mean age at first recording of a PDD diagnosis in the GPRD database was 6.3 years (SD = 4.6). Consistent with previous estimates, the proportion of subjects experiencing regression in the course of their development was 19%. Inter-rater reliability for the presence of a PDD diagnosis was good (kappa =.73), and agreement on clinical features such as regression, age of parental recognition of first symptoms, language delay and presence of epilepsy was also good (kappas ranging from.56 to 1.0).
  
  
  CONCLUSIONS
  This study provides evidence that the positive predictive value of a diagnosis of autism recorded in the GPRD is high.
authors.affiliation: McGill University, Montreal Children's Hospital, 4018 St Catherine St West, Montreal, QC, Canada, H3Z 1P2. eric.fombonne@mcgill.ca
authors.forename: Eric
authors.initials: E
authors.lastname: Fombonne
authors.forename: Lisa
authors.initials: L
authors.lastname: Heavey
authors.forename: Liam
authors.initials: L
authors.lastname: Smeeth
authors.forename: Laura C
authors.initials: LC
authors.lastname: Rodrigues
authors.forename: Claire
authors.initials: C
authors.lastname: Cook
authors.forename: Peter G
authors.initials: PG
authors.lastname: Smith
authors.forename: Linyan
authors.initials: L
authors.lastname: Meng
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Hall
mesh_terms: D017668:Age of Onset; D000465:Algorithms; D001321:Autistic Disorder / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D016022:Case-Control Studies; D002659:Child Development Disorders, Pervasive / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D002675:Child, Preschool; D015331:Cohort Studies; D016208:Databases, Factual / Q000592:standards*; D003937:Diagnosis, Differential; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005194:Family Practice / Q000592:standards* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D016347:Medical Records Systems, Computerized / Q000145:classification*; D011336:Probability; D040442:Public Health Informatics; D006113:United Kingdom / Q000453:epidemiology