An updated review of the prevalence of invalid performance on the Immediate Post-Concussion and Cognitive Testing (ImPACT)

Objective: Performance validity assessment is an important component of concussion baseline testing and Immediate Post-Concussion and Cognitive Testing (ImPACT) is the most commonly used test in this setting. A review of invalid performance on ImPACT was published in 2017, focusing largely on the default embedded validity indicator (Default EVI) provided within the test. There has since been a proliferation in research evaluating the classification accuracy of the Default EVI against independently developed, alternative ImPACT-based EVIs, necessitating an updated review. The purpose of this study was to provide an up-to-date review of the prevalence of invalid performance on ImPACT and to examine the relative effectiveness of ImPACT-based EVIs. Method: Literature related to the prevalence of invalid performance on ImPACT and the effectiveness of ImPACT-based EVIs, published between January 2000 and May 2020, was critically reviewed. Results: A total of 23 studies reported prevalence of invalid performance at baseline testing using ImPACT. Six percent of baseline assessments were found to be invalid by the ImPACT's Default EVI, and between 22.31% and 34.99% were flagged by alternative EVIs. Six studies assessed the effectiveness of ImPACT-based EVIs, with the Default EVI correctly identifying experimental malingerers only 60% of the time. Alternative ImPACT-based EVIs identified between 73% and 100% of experimental malingerers. Conclusions: The ImPACT's Default EVI is not sufficiently sensitive, and clinicians should consider alternative indicators when assessing invalid performance. Accordingly, the base rate of invalid performance in athletes at baseline testing is likely well above the 6% previously reported.

Automated summary

This study critically reviewed literature on the prevalence of invalid performance on ImPACT and the effectiveness of ImPACT-based EVIs. It was found that the Default EVI of ImPACT is not sensitive enough, and alternative indicators should be considered when assessing invalid performance.