Clinical utility of WAIS-IV ‘excessive decline from premorbid functioning’ scores to detect invalid test performance following traumatic brain injury

Abstract

Objective: Excessive Decline from Premorbid Functioning (EDPF), an atypical discrepancy between demographically predicted and obtained Wechsler Adult Intelligence Scale-4th Edition (WAIS-IV) scores, has been recently proposed as a potential embedded performance validity test (PVT). This study examined the clinical utility of EDPF scores to detect invalid test performance following traumatic brain injury (TBI).

Methods: Participants were 194 U.S. military service members who completed neuropsychological testing on average 2.4 years (SD = 4.0) following uncomplicated mild, complicated mild, moderate, severe, or penetrating TBI (Age: M = 34.0, SD = 9.9). Using TBI severity and PVT performance (i.e., PVT Pass/Fail), participants were classified into three groups: Uncomplicated Mild TBI-PVT Fail (MTBI-Fail; n = 21), Uncomplicated Mild TBI-PVT Pass (MTBI-Pass; n = 94), and Complicated Mild to Severe/Penetrating TBI-PVT Pass (CM/STBI-Pass; n = 79). Seven EDPF measures were calculated by subtracting WAIS-IV obtained index scores from the demographically predicted scores from the Test of Premorbid Functioning (TOPF). Cutoff scores to detect invalid test performance were examined for each EDPF measure separately.

Results: The MTBI-Fail group had higher scores than the MTBI-Pass and CM/STBI-Pass groups on five of the seven EDPF measures (p<.05). Overall, the EDPF measure using the Processing Speed Index (EDPF-PSI) was the most useful score to detect invalid test performance. However, sensitivity was only low to moderate depending on the cutoff score used.

Conclusions: These findings provide support for the use of EDPF as an embedded PVT to be considered along with other performance validity data when administering the WAIS-IV.

Keywords:

• Wechsler Adult Intelligence Scale
• test of premorbid functioning
• performance validity
• effort
• excessive decline

Acknowledgement

The authors would like to thank the service members and veterans for their time and commitment to participating in the research. The authors would also like to acknowledge the efforts of the larger team of research coordinators, research associates, research assistants, program managers, and senior management who contribute to the DVBIC 15-Year Longitudinal TBI Study.

Disclosure statement

The views expressed in this article are those of the authors and do not reflect the official policy of the Department of Army, Navy, Air Force, Department of Defense, or U.S. Government. The identification of specific products, scientific instrumentation, or organizations is considered an integral part of the scientific endeavor and does not constitute endorsement or implied endorsement on the part of the author, Department of Defense, or any component agency.

Additional information

Funding

This study is part of the larger Defense and Veterans Brain Injury Center (DVBIC) 15-Year Longitudinal TBI Study designed to respond to a Congressional mandate (Sec721 NDAA FY2007).