title: Pervasive developmental disorders in preschool children.
abstract: BACKGROUND
  Prevalence rates of autism-spectrum disorders are uncertain, and speculation that their incidence is increasing continues to cause concern.
  
  
  OBJECTIVE
  To estimate the prevalence of pervasive developmental disorders (PDDs) in a geographically defined population of preschool children.
  
  
  METHODS
  Survey conducted July 1998 to June 1999 in Staffordshire, England. The area's 15 500 children aged 2.5 to 6.5 years were screened for developmental problems. Children with symptoms suggestive of a PDD were intensively assessed by a multidisciplinary team, which conducted standardized diagnostic interviews and administered psychometric tests.
  
  
  METHODS
  Prevalence estimates for subtypes of PDDs.
  
  
  RESULTS
  A total of 97 children (79.4% male) were confirmed to have a PDD. The prevalence of PDDs was estimated to be 62.6 (95% confidence interval, 50.8-76.3) per 10 000 children. Prevalences were 16.8 per 10 000 for autistic disorder and 45.8 per 10 000 for other PDDs. The mean age at diagnosis was 41 months, and 81% were originally referred by health visitors (nurse specialists). Of the 97 children with a PDD, 25.8% had some degree of mental retardation and 9.3% had an associated medical condition.
  
  
  CONCLUSIONS
  Our results suggest that rates of PDD are higher than previously reported. Methodological limitations in existing epidemiological investigations preclude interpretation of recent high rates as indicative of increased incidence of these disorders although this hypothesis requires further rigorous testing. Attention is nevertheless drawn to the important needs of a substantial minority of preschool children.
authors: MRC Child Psychiatry Unit, Institute of Psychiatry/King's College London, Denmark Hill, London SE5 8AF, England.
authors: S
authors: S
authors: Chakrabarti
authors: E
authors: E
authors: Fombonne
mesh_terms: D001321:Autistic Disorder / Q000453:epidemiology; D002648:Child; D002659:Child Development Disorders, Pervasive / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology*; D002675:Child, Preschool; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D008607:Intellectual Disability / Q000150:complications; D008297:Male; D015995:Prevalence