FORSKNINGSABSTRACT, PRÆVALENS & INCIDENS

Prævalens af autismespektrumforstyrrelser i en population af børn i South Thames: Special Needs and Autism Project (SNAP)

Forskere har undersøgt udbredelsen – prævalensen – af autisme blandt 9-10 årige børn i det sydlige London. I alt indgår næsten 57.000 børn i undersøgelsen. Ud over de børn, der allerede havde en autismediagnose har forskerne udredt et udsnit af børn, der ikke tidligere var diagnosticeret, men som var i risikogruppen, fordi de modtog vidtgående specialundervisning. Resultatet er, at ikke mindre end 1,16 % af alle 9-10 årige har autisme eller andre gennemgribende udviklingsforstyrrelser. Det svarer til 1 barn ud af 86. Udbredelsen af diagnosen klassisk (infantil) autisme er 3,9 ‰, mens andre gennemgribende udviklingsforstyrrelser tegner sig for 7,7 ‰. Disse prævalenstal er betydelig højere end man tidligere har fundet. Det er dog uklart om disse høje tal skyldes en bredere screening, reviderede diagnosekriterier eller en voksende incidens (hyppighed).

Emneord: incidens; prævalens; skolebørn; 9 år; 10 år; screening; specialundervisning;

Baird, G., Simonoff, E., Pickles, A., Chandler, S., Loucas, T., Meldrum, D., et al. (2006) . Prevalence of disorders of the autism spectrum in a population cohort of children in South Thames: the Special Needs and Autism Project (SNAP). Lancet, 368(9531), 210-215.

BACKGROUND: Recent reports have suggested that the prevalence of autism and related spectrum disorders (ASDs) is substantially higher than previously recognised. We sought to quantify prevalence of ASDs in children in South Thames, UK. METHODS: Within a total population cohort of 56 946 children aged 9-10 years, we screened all those with a current clinical diagnosis of ASD (n=255) or those judged to be at risk for being an undetected case (n=1515). A stratified subsample (n=255) received a comprehensive diagnostic assessment, including standardised clinical observation, and parent interview assessments of autistic symptoms, language, and intelligence quotient (IQ). Clinical consensus diagnoses of childhood autism and other ASDs were derived. We used a sample weighting procedure to estimate prevalence. FINDINGS: The prevalence of childhood autism was 38.9 per 10,000 (95% CI 29.9-47.8) and that of other ASDs was 77.2 per 10,000 (52.1-102.3), making the total prevalence of all ASDs 116.1 per 10,000 (90.4-141.8). A narrower definition of childhood autism, which combined clinical consensus with instrument criteria for past and current presentation, provided a prevalence of 24.8 per 10,000 (17.6-32.0). The rate of previous local identification was lowest for children of less educated parents. INTERPRETATION: Prevalence of autism and related ASDs is substantially greater 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.

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Digital Object Identifier: 10.1016/S0140-6736(06)69041-7

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Joi Bay / 16.08.2006)