How sandbag-able are concussion sideline assessments? A close look at eye movements to uncover strategies

ABSTRACT

Background: Sideline diagnostic tests for concussion are vulnerable to volitional poor performance (“sandbagging”) on baseline assessments, motivated by desire to subvert concussion detection and potential removal from play. We investigated eye movements during sandbagging versus best effort on the King-Devick (KD) test, a rapid automatized naming (RAN) task.

Methods: Participants performed KD testing during oculography following instructions to sandbag or give best effort.

Results: Twenty healthy participants without concussion history were included (mean age 27 ± 8 years). Sandbagging resulted in longer test times (89.6 ± 39.2 s vs 48.2 ± 8.5 s, p < .001), longer inter-saccadic intervals (459.5 ± 125.4 ms vs 311.2 ± 79.1 ms, p < .001) and greater numbers of saccades (171.4 ± 47 vs 138 ± 24.2, p < .001) and reverse saccades (wrong direction for reading) (21.2% vs 11.3%, p < .001). Sandbagging was detectable using a logistic model with KD times as the only predictor, though more robustly detectable using eye movement metrics.

Conclusions: KD sandbagging results in eye movement differences that are detectable by eye movement recordings and suggest an invalid test score. Objective eye movement recording during the KD test shows promise for distinguishing between best effort and post-injury performance, as well as for identifying sandbagging red flags.

KEYWORDS:

• Concussion
• king-Devick
• rapid Automatized Naming Tasks
• saccades
• inter-saccadic Interval
• sandbagging

Authors’ contributions

Conception and design of the study: JRR, TEH, LJB, SLG, JCR

Acquisition and analysis of data: JRR, TEH, JM, WD, OI, YC, IS, JCR

Substantial manuscript drafting: JRR, TEH, JCR

Editing and approval of final manuscript: all authors

Disclosure of interest

No author has received any financial compensation or consultant fees from King-Devick Test, Inc. No author has other disclosures pertinent to this study.

Consent to participate

Written informed consent for participation was obtained from each participant.

Consent for publication

Written informed consent for publication was obtained from each participant. No private health information is included for publication.

Data availability

Original data will be made available if requested.

Ethics approval

All research protocols were approved by the NYU Institutional Review Board.

Additional information

Funding

5K12HDOO1097 NICHD and NCMRR, National Institutes of Health Rehabilitation Medicine Scientist Training Program (JRR). Empire Clinical Research Investigator Program (ECRIP);Empire Clinical Research Investigator Program (ECRIP).;NICHD and NCMRR, National Institutes of Health Rehabilitation Medicine Scientist Training Program [5K12HDOO1097];