Nih toolbox premorbid ability adjustments: Application in a traumatic brain injury sample.
James A Holdnack, David S Tulsky, Jerry Slotkin and 4 others
PMID 29265870WHAT IT FOUND
In NIH Toolbox cognitive testing after TBI, oral reading adjustments changed individual scores and flagged slightly different people, but did not increase overall identification of cognitive difficulties.
Key findings
01Reading scores and education level often give different premorbid estimates: 26.1% of low-education controls scored above the mean of the highest education group, 43.5% of those with less than high school scored above the mean of those with some college, and 14.8% of college graduates scored below the mean of those with less than high school.
02Reading-adjusted fluid scores can move an individual's score by as much as -21 to +23 standard-score points on the age-and-reading Fluid Composite, and by -12 to +11 T-score points on the demographic-and-reading Fluid Composite.
03Age-and-reading scores did not increase the overall rate of identifying cognitive difficulties, but they identified slightly different people and made rates more similar across low, average, and high premorbid ability.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The reading-referenced scores are not normative data; they are a specific reference group. The standardization sample was not stratified by reading ability, so it may not fully represent reading ability in the general population. The TBI sample may not represent all levels of premorbid ability by age, education, or ethnicity. Injury severity groups were unequal, and the small number of moderate injuries limits generalizability. Neither sample was screened for performance validity, so non-credible effort could affect reading and fluid scores and change interpretation. Severe TBI participants had lower reading scores, so reading may underestimate premorbid ability in severe injury, especially when demographically adjusted reading T-scores are below 40.
Declared interests
The authors reported no financial interest in the NIH Toolbox.
The easy way to misread this
Do not use the reading-adjusted scores as a stand-alone diagnosis. They are a reference-group comparison, not normative data, and low reading scores may reflect severe injury or poor effort rather than premorbid ability, especially when demographically adjusted reading T-scores are below 40.