The prevalence* of childhood autism and related disorders in the UK may be substantially higher than previously thought, according to an article in this week's issue of The Lancet.
Autism is a lifelong developmental disability that affects the way a person communicates and relates to other people. All people with autism have impaired social interactions, communication, and imagination. People with related disorders, know as autism spectrum disorders (ASDs), usually have a mixture of autistic features. Accurate ASD prevalence estimates are needed for the planning of educational, social, and medical services for this group. Prior to the 1990s, researchers estimated that there were four to five cases of autism per 10 000 people but recent reports suggest that the prevalence is much higher.
To investigate, Gillian Baird (Guy's and St Thomas' Hospital, London, UK) and colleagues calculated the prevalence of ASDs in children aged 9-10 years in South London, UK. In 2001 they identified children with any form of ASD (255) and those with special educational needs (1515) as possible unidentified cases of ASD from a special needs register. 255 children were randomly selected for in depth clinical assessment. The researchers found 39 children per 10 000 had autism and 77 per 10 000 had ASD, making the total prevalence of all types of ASD 116 per 10 000. The prevalence based on previous locally identified children with ASD would have been 44 per 10 000, state the authors. The findings indicate that children with some form of ASD constitute 1% of the child population in the UK.
Professor Baird states: "Prevalence of autism and related ASDs is substantially higher than previously recognised. Whether the increase is due to better ascertainment, broadening diagnostic criteria, or increased incidence is unclear. Services in health, education, and social care will need to recognise the needs of children with some form of ASD, who constitute 1% of the child population."
The study highlights the need for agreed definitions in prevalence studies and for designs that are not reliant on local systems to identify children with ASD, conclude the authors.
*Prevalence refers to the number of cases present in a population, whereas incidence is the number of new cases in a population.
See also accompanying Comment.
Katie Fleming or Catriona Richardson,
Communications Department, Guy's and St Thomas' NHS Foundation Trust, London, UK.
T) 020 7188 5577.
Notes to editors
Definition of autism from The National Autistic Society http://www.nas.org.uk/
Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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