Screening for intellectual disability in Dutch psychiatrically disturbed detainees: Assessing the psychometric properties of the Screener for Intelligence and Learning Disability (SCIL).
Ankie Yvonne Maria van Esch, Jolanda de Vries, Erik David Marco Masthoff
PMID 32578391WHAT IT FOUND
A brief screen for possible intellectual disability in psychiatrically disturbed Dutch detainees worked, but less well than in regular prisoners.
The authors recommended a score threshold of 20.5 to flag more people at risk.
Key findings
01The SCIL discriminated between at-risk and not-at-risk detainees with an area under the curve of 0.84 in the 214 who also had WAIS-IV IQ scores.
02At the original cut-off of 19.5, the SCIL caught 72.0% of people with IQ below 85 and correctly cleared 77.0% of people not at risk; at 20.5, it caught 76.7% and correctly cleared 72.9%.
03Internal consistency was Cronbach's alpha 0.72, lower than 0.83 in regular prison populations.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study used retrospective files. From 2,221 initial files, only 492 remained after exclusions, and only 214 had WAIS-IV IQ scores for validation. Diagnoses were made using DSM-IV-TR, not DSM-5, and the screen was validated against IQ alone, not adaptive functioning. Test-retest reliability could not be examined, and inter-rater reliability was not calculated in the usual way because each SCIL was done by one psychologist. The sample was 93.9% male and came from psychiatric detention centres, so it may not apply to other groups. The recommended threshold of 20.5 may increase false positives.
The easy way to misread this
Do not read the SCIL as a diagnosis of intellectual disability. It is a screen. In this mentally ill detainee sample, the recommended cut-off of 20.5 caught 76.7% of people with IQ below 85, and validation used IQ scores alone rather than adaptive functioning.