The Prudhoe Cognitive Function Test, a scale to assess cognitive function in adults with Down's syndrome: inter-rater and test-retest reliability.
The PCFT gives highly stable cognitive scores no matter who gives it or when.
01Research in Context
What this study did
Katz et al. (2003) checked how steady the Prudhoe Cognitive Function Test (PCFT) is.
They gave the test twice to adults with Down syndrome.
Different raters also scored the same people to see if answers stayed the same.
What they found
The scores barely moved. Test-retest reliability was near perfect.
Inter-rater agreement was just as high. Specialists and non-specialists got the same numbers.
How this fits with other research
Jennett et al. (2003) released a companion paper the same year. That team warned of floor effects in profound ID. Together the papers say: PCFT is reliable, but use another tool if the client scores at the bottom.
Poppes et al. (2010) later shortened the test. They showed the brief forms match the full PCFT, so you can save time without losing accuracy.
de Korte et al. (2021) stretched the tool further. They validated an Italian short form for aging adults with any intellectual disability, proving the test travels across language and age.
Why it matters
You now have a rock-solid cognitive ruler for adults with Down syndrome. Use the full PCFT for deep profiles, or grab a short form when time is tight. Either way, you can trust the numbers you write in the report.
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02At a glance
03Original abstract
BACKGROUND: The Prudhoe Cognitive Function Test (PCFT) was designed to measure cognitive function in subjects with all degrees of intellectual disability (ID) and to be administered by non-specialist raters. The aim of the present study was to measure the test-retest and inter-rater reliability of the PCFT. METHODS: Three raters, one a specialist and two non-specialists, administered the PCFT to 14 subjects with Down's syndrome on two occasions separated by 4 weeks. RESULTS: The intra-class correlation coefficients (ICCs) between the rater pairs (n=3) were 0.99, 0.99 and 0.98 (P<0.01). Floor effects were recorded for two items. The ICC for test-retest reliability was 0.99 (P<0.01). CONCLUSIONS: The PCFT is a highly reliable instrument when used by either specialist or non-specialist raters. It has excellent temporal stability.
Journal of intellectual disability research : JIDR, 2003 · doi:10.1046/j.1365-2788.2003.00450.x