The CAST (Childhood Asperger Syndrome Test): test accuracy.
CAST reliably flags possible autism in school-age kids, yet half of its high scores are false alarms, so always confirm with full evaluation.
01Research in Context
What this study did
Williams et al. (2005) checked how well the Childhood Asperger Syndrome Test (CAST) spots autism traits in regular UK primary schools. Parents filled out the 37-item yes/no checklist about their child. Researchers compared scores to clinical diagnoses to see how often the test got it right.
What they found
At a cut-off of 15, CAST caught every child later diagnosed with an autism spectrum condition. It also correctly ruled out 97 % of kids without the condition. Yet only half of the children who scored above the cut-off actually had ASD; the rest were false alarms.
How this fits with other research
Allison et al. (2007) ran a direct follow-up and showed that high CAST scores stay pretty stable two months later. This backs the 2005 accuracy data: if a child scores high once, they usually score high again.
Sun et al. (2014) took the same test to China and found similar two-factor structure and good validity, proving the tool travels well across cultures.
Fitzpatrick et al. (2017) shortened the CAST to 28 items in Spanish and still kept strong sensitivity, giving busy clinics a faster option.
No contradictions appear; each new study keeps the core findings while adding practical tweaks like shorter forms or new languages.
Why it matters
You can use CAST as a first-step screener in research or clinic intake, but always follow up with full assessment. Remember the 50 % false-positive rate: a high score means “look closer,” not “autism confirmed.” If you work with multilingual families, know that validated Spanish, Mandarin, and English versions exist, letting you screen without a translator.
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Join Free →Hand the 37-item CAST to parents of any 5-11-year-old you suspect; use cut-off 15 to decide who needs a full assessment next.
02At a glance
03Original abstract
The Childhood Asperger Syndrome Test (CAST) is a parental questionnaire to screen for autism spectrum conditions. In this validation study, the CAST was distributed to 1925 children aged 5-11 in mainstream Cambridgeshire schools. A sample of participants received a full diagnostic assessment, conducted blind to screen status. The sensitivity of the CAST, at a designated cut-point of 15, was 100 percent, the specificity was 97 percent and the positive predictive value was 50 percent, using the group's consensus diagnosis as the gold standard. The accuracy indices varied with the case definition used. The sensitivity of the accuracy statistics to case definition and to missing data was explored. The CAST is useful as a screening test for autism spectrum conditions in epidemiological research. There is not currently enough evidence to recommend the use of the CAST as a screening test within a public health screening programme in the general population.
Autism : the international journal of research and practice, 2005 · doi:10.1177/1362361305049029