Validating the Communication and Symbolic Behavior Scales-Developmental Profile Infant-Toddler Checklist (CSBS-DP ITC) Beyond Infancy in the CDKL5 Deficiency Disorder.
Jacinta Saldaris, Helen Leonard, Kingsley Wong and 6 others
PMID 37184758WHAT IT FOUND
The CSBS-DP ITC accurately distinguishes children with CDKL5 deficiency disorder by communication and motor abilities, but scores cluster at the bottom.
Use the total score, not the three subscales, and expect limited sensitivity to small changes.
Key findings
01The three subscales (Social, Speech, Symbolic) are too highly correlated to be used separately in this population; the total score is the valid measure.
02Total scores significantly distinguished children by their ability to walk, feed, grasp objects, and communicate, confirming the tool measures functional status.
0357.4% of all checklist items scored zero, and the distribution was heavily skewed, indicating a floor effect that may mask subtle improvements.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
The study found a significant floor effect, with over half of the items scored as zero, which limits the tool's ability to detect small changes in severely impaired children. The three subscales (Social, Speech, Symbolic) could not be used independently because they were too highly correlated, reducing the diagnostic utility of the profile. The sample was recruited from a specific database (ICDD), which may not represent all children with CDKL5 deficiency disorder globally. The tool does not address the use of Augmentative and Alternative Communication (AAC) devices, potentially underestimating communication in children who use them.
Declared interests
Funded by the International Foundation for CDKL5 Research, National Institutes of Health, Stan Perron Charitable Foundation, and Curtin University.
The easy way to misread this
Do not interpret the high test-retest reliability (ICC 0.96) as evidence that the tool is sensitive to change. It indicates stability in a static population, not the ability to detect improvement. The floor effect means many children will score near zero regardless of small therapeutic gains.