The Childhood Asperger Syndrome Test (CAST): test-retest reliability in a high scoring sample.
CAST scores hold steady for two months in high-scoring kids, so you can track group progress but still need fuller tests for each child.
01Research in Context
What this study did
Allison et al. (2007) asked a simple question. If a child scores high on the Childhood Asperger Syndrome Test, will the score stay high two months later? They gave the 37-item parent checklist twice to families already flagged by the CAST. The gap between tests averaged eight weeks. No coaching or treatment happened between the two screens.
What they found
Seven out of ten children kept the same pass-fail status. The kappa was 0.41 and the rho was 0.67. Those numbers mean moderate reliability. In plain words, the CAST is steady enough for group research, but not tight enough to hang a single diagnosis on.
How this fits with other research
Williams et al. (2005) had already shown the CAST can spot autism traits with 100% sensitivity. Carrie adds the missing piece: scores don't jump around much in the short term. Sun et al. (2013) later repeated the same test-retest idea in Mandarin-speaking children and got similar kappa values (0.53-0.64). Fitzpatrick et al. (2017) then stretched the tool into Spanish and found fresh cut-offs still work. Together the papers build a bridge: first accuracy, then stability, then cross-language use.
Why it matters
You can hand the CAST to parents before and after an intervention and trust that big score changes mean something real. Don't use it alone to decide if a child qualifies for services. Pair it with other tools and keep the two-month window in mind when you re-screen.
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02At a glance
03Original abstract
The Childhood Asperger Syndrome Test (CAST) is a 37-item parental self-completion questionnaire designed to screen for high-functioning autism spectrum conditions in epidemiological research. The CAST has previously demonstrated good accuracy for use as a screening test, with high sensitivity in studies with primary school aged children in mainstream schools. This study aimed to investigate test-retest reliability of the CAST in a high scoring sample. To this end, 73 parents filled in the second CAST (CAST-2) within approximately 2 months of the first administration of the CAST (CAST-1). Agreement above and below the cut-point of 15 was investigated. The kappa statistic for agreement (<15 versus > or =15) was 0.41. It was found that 70 percent (95% CI: 58, 80) of children did not move across the cut-point of 15. The correlation between the two test scores was 0.67 (Spearman's rho). The CAST shows moderate test-retest reliability in a high scoring sample, further evidence that it is a relatively robust screening tool for epidemiological research.
Autism : the international journal of research and practice, 2007 · doi:10.1177/1362361307075710