Estimating Premorbid Ability in Rehabilitation Patients Using the Test of Premorbid Functioning and Wide Range Achievement Test–Fourth Edition

Abstract

Objective: This study examined premorbid ability estimate concordance using Test of Premorbid Functioning predicted Full Scale Intelligent Quotient (TOPF-IQ) and Wide Range Achievement Test–Fourth Edition Word Reading (WRAT4-WR). Method: The sample ( N = 145) was 28% female with average age and education of 40.6 and 13.2 years, respectively. Outpatient neuropsychological evaluations were conducted in a rehabilitation setting. Measures included the TOPF, WRAT4-WR, Wechsler Adult Intelligence Scale–Fourth Edition, and other neuropsychological tests. Non-WAIS measures defined impairment groups. Analyses included t tests, pairwise correlations, concordance correlation coefficients, and root mean square differences. Results: TOPF-IQ, WRAT4-WR, and Full Scale Intelligent Quotient scores were not significantly different but were lower than normative mean. TOPF-IQ and WRAT4-WR showed acceptable agreement (concordance correlation coefficient = .92; root mean square difference = 5.9). Greater premorbid–current ability differences were observed in the impaired group. TOPF-IQ and WRAT4-WR showed lower but similar agreement with Full Scale Intelligence Quotient in the unimpaired group. Conclusions: Findings support the WRAT4-WR in predicting premorbid ability in rehabilitation settings.