Advanced Clinical Interpretation of the WAIS-IV and WMS-IV: Prevalence of Low Scores Varies by Level of Intelligence and Years of Education

Alberta Children's Hospital and University of Calgary, Canada.
Assessment (Impact Factor: 3.29). 06/2011; 18(2):156-67. DOI: 10.1177/1073191110385316
Source: PubMed

ABSTRACT Clinicians can use the base rates of low scores in healthy people to reduce the likelihood of misdiagnosing cognitive impairment. In the present study, base rates were developed for the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) and Wechsler Memory Scale-Fourth Edition (WMS-IV) using 900 healthy adults and validated on 28 patients with moderate or severe traumatic brain injuries (TBIs). Results indicated that healthy people obtain some low scores on the WAIS-IV/WMS-IV, with prevalence rates increasing with fewer years of education and lower predicted intelligence. When applying the base rates information to the clinical sample, the TBI patients were 13 times more likely to be identified as having a low cognitive profile compared with the controls. Using the base rates information is a psychometrically advanced method for establishing criteria to determine low cognitive abilities on the WAIS-IV/WMS-IV.

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    • "ith and without cognitive impairment ( Brooks et al . , 2011 ) . Convergent validity was supported by our data . Furthermore , this study is one of the first to highlight group differences between com - plicated mild / moderate and severe TBI using the WMS ; most previous WMS – II / WMS – IV work in TBI has focused on only moderate or severe TBI ( Brooks et al . , 2011 ; Langeluddecke & Lucas , 2005 ; Skandsen et al . , 2010 ; Walker , Batchelor , Shores , & Jones , 2009 ) , has not distinguished between mild and complicated mild TBI ( Fisher et al . , 2000 ; West et al . , 2011 ) , or has not distinguished complicated mild TBI from other TBI groups ( i . e . , only exam - ined TBI relative to control"
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