Abstract
Objective: To evaluate predictors of performance validity testing (PVT) and clinical outcome in patients presenting to a specialty clinic with a mild traumatic brain injury (mTBI).
Setting: An outpatient mTBI specialty clinic.
Participants: Seventy-six (47% female) patients aged 16 to 66 (mean = 40.58, SD = 14.18) years within 3 to 433 days (mean = 30.63, SD = 54.88, median = 17.00) of a suspected mTBI between 2018 and 2019.
Design: A cross-sectional, observational study comparing patients who passed PVT (n = 43) with those who failed (n = 33). A logistic regression (LR) was conducted to evaluate factors that predicted failed PVT. Independent-samples t tests and general linear model were used to evaluate PVT groups on clinical outcomes. The LR with a receiver operating characteristic (ROC) curve was conducted to evaluate embedded validity indicators.
Main Measures: Performance validity testing, computerized neurocognitive testing, vestibular/oculomotor screening, symptom reports.
Results: At their initial clinic visit 43% of patients failed PVT. PVT failure was predicted by presence of secondary gain (odds ratio [OR] = 8.11, P = .02), while a history of mental health predicted passing of PVT (OR = 0.29, P = .08). Those who failed PVT performed significantly worse on computerized neurocognitive testing (P < .05) and took an average of 33 days longer to return to work (P = .02). There was no significant difference (P = .20) in recovery time between failed/passed PVT groups when covarying for those who sustained a work injury. Word memory learning percentage less than 69% and design memory learning percentage less than 50% accurately classified patients who failed PVT (area under the ROC curve = 0.74; P < .001).
Conclusion: Secondary gain was the best predictor of failed PVT. Patients presenting for mTBI evaluation and rehabilitation who fail PVT demonstrate worse performance on cognitive testing and take longer to return to work post-injury, but recover in a similar time frame compared with those who pass PVT. Clinicians should be cautious in discounting patients who yield invalid test results, as these patients appear to be able to achieve recovery in a treatment setting.