Do Effortful Epilepsy Patients Fall Below Performance Validity Test Cutoffs At Higher Rates Than Is Considered Acceptable?

Abstract Objective Factors specific to an epilepsy population (e.g., medications, psychiatric comorbidities, localization) may result in higher false positive rates on performance validity tests (PVT), rendering the results more equivocal. This study examined whether specificity is reduced in effortful epilepsy patients on the Warrington Recognition Memory Test - Words (WRMT-W) and Test of Memory Malingering (TOMM). Method 53 epilepsy patients referred for neuropsychological evaluation through the University of Washington Regional Epilepsy Center were examined. Patients were majority male (56.6%) and Caucasian (79.2%). Average age and education were 36.1 (SD = 13.03) and 13.4 years (SD = 2.39), respectively. Patients with an intelligence quotient of <70, history of brain surgery, and those who seized during testing were excluded. Patients clinically observed to have reduced effort with 2+ PVT failures were excluded (n = 3). Frequency tables for WRMT-W and TOMM performances were utilized to examine specificity based on prior cutoffs identified for these measures. Results The WRMT-W cutoff of ≤42 was associated with 88.7% specificity. TOMM Trial 2 and Retention cutoffs of <45 were associated with 98.1% and 100% specificity, respectively. The WRMT-W cutoff was associated with 91.7% specificity in language dominant hemisphere onset epilepsy patients (n = 16). None performed below cutoffs on the TOMM. All nondominant hemisphere onset patients (n = 8) performed above WRMT-W and TOMM cutoffs. Conclusions Use of the WRMT-W and TOMM in an epilepsy population is associated with an acceptable false positive rate (specificity around 90%). However, future studies examining the sensitivity of these measures in epilepsy patients should be performed.