Psychometric evaluation of a measure of cognitive decline in elderly people with mental retardation.
The Short IQCODE is too unreliable for elderly clients with ID—use newer screeners like s-PCFT-I or DIAB.
01Research in Context
What this study did
The team tested the Short IQCODE on elderly adults with intellectual disability.
They wanted to see if the short questionnaire could track cognitive decline.
The study was a small case series with no control group.
What they found
Internal consistency was only moderate.
Test-retest and inter-rater reliability were poor.
Validity was weak, so the tool is not ready for use.
How this fits with other research
Drijver et al. (2025) and de Korte et al. (2021) now offer better tools.
Their short tests show excellent reliability for aging clients with ID.
Vassos et al. (2023) reviewed nine mental-health measures and also found only four with solid data.
Together these papers show the field has moved past the 1998 IQCODE.
Why it matters
If you screen older clients with ID, skip the Short IQCODE.
Pick the Italian s-PCFT-I or the new DIAB instead.
Both take about ten minutes and give scores you can trust.
Update your assessment list today so you do not rely on a shaky tool.
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02At a glance
03Original abstract
Forty elderly persons with mental retardation were assessed by their care providers on a modified version of the Short Informant Questionnaire on Cognitive Decline in The Elderly (IQCODE) an instrument designed to quantify cognitive decline in elderly people in the general population. They were also assessed for IQ, aberrant behavior, and current mental status; test-retest and interrater reliability were evaluated as well. Internal consistency, as assessed by coefficient alpha, was moderately high (alpha = .86). Test-retest reliability was mediocre and interrater reliability levels did not reach statistical significance. The Short IQCODE was not correlated with a variety of demographic features or with behavior ratings, showing evidence of divergent validity. However, the Short IQCODE was only weakly (nonsignificantly) correlated with a measure of current mental status, which challenges its concurrent validity. The Short IQCODE probably needs to be modified further for satisfactory psychometric performance in people with mental retardation. However, some features of this study may have resulted in suboptimal estimates of the Short IQCODE's psychometric characteristics.
Research in developmental disabilities, 1998 · doi:10.1016/s0891-4222(97)00029-2