title: Estimates of premorbid ability in a neurodegenerative disease clinic population: comparing the Test of Premorbid Functioning and the Wide Range Achievement Test, 4th Edition.
abstract: OBJECTIVE
  Two frequently used measures to assess premorbid intellectual ability include the Wide Range Achievement Test, 4th Edition Reading Subtest (WRAT-4 READ) and the Test of Premorbid Functioning (TOPF). The present study compared estimates obtained from these measures in a neurodegenerative disease population.
  
  
  METHODS
  Records from 85 referrals seen for neuropsychological evaluation in a neurodegenerative disorders clinic were reviewed. Evaluations included TOPF, WRAT-4 READ, and measures of memory, reasoning, language, and executive functioning. Pairwise correlations and concordance correlation coefficients (CCC) were calculated between raw scores and predicted intelligence estimates. Discrepancy scores were calculated between estimates and data were divided into three groups based on size of standardized discrepancy score: Equal, WRAT-4 READ > TOPF, and TOPF > WRAT-4 READ. analysis of variances compared groups on demographic characteristics and cognitive performance.
  
  
  RESULTS
  Despite strong Pearson correlation, CCC between predicted IQ estimates showed poor agreement between measures, with evidence of both fixed and proportional bias. Discrepancies ranged from -24.0 to 22.0 (M = 1.78, SD = 6.65), with TOPF generating higher estimates on average. Individuals performing better on WRAT-4 READ were significantly older (M age = 76.26, SD = 7.53) than those performing similarly on both measures and those performing better on TOPF (F (2, 82) = 7.31, p < .001). All other comparisons between groups on demographic variables and cognitive measures were non-significant.
  
  
  CONCLUSIONS
  Estimates of premorbid intelligence obtained from the TOPF and WRAT-4 READ have a strong linear relationship, but systematically generate inconsistent estimates in a neurodegenerative disease clinical sample and should not be used interchangeably.
authors.affiliation: a Cleveland Clinic Lou Ruvo Center for Brain Health , Las Vegas , NV , USA.
authors.forename: Jody-Lynn
authors.initials: JL
authors.lastname: Berg
authors.affiliation: a Cleveland Clinic Lou Ruvo Center for Brain Health , Las Vegas , NV , USA.
authors.forename: January
authors.initials: J
authors.lastname: Durant
authors.affiliation: a Cleveland Clinic Lou Ruvo Center for Brain Health , Las Vegas , NV , USA.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Banks
authors.affiliation: a Cleveland Clinic Lou Ruvo Center for Brain Health , Las Vegas , NV , USA.
authors.forename: Justin B
authors.initials: JB
authors.lastname: Miller
mesh_terms: D000124:Achievement; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000523:psychology; D003071:Cognition; D056344:Executive Function; D005260:Female; D006801:Humans; D007361:Intelligence Tests; D007807:Language Tests; D008297:Male; D008568:Memory; D008606:Mental Processes; D008875:Middle Aged; D019636:Neurodegenerative Diseases / Q000175:diagnosis* / Q000523:psychology*; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D011932:Reading; D015203:Reproducibility of Results
keywords: Premorbid ability; Test of Premorbid Functioning; Wide Range Achievement Test; neurodegenerative disease