Overground and Virtual Reality Gait Speed Are Associated With Atypical Symptom Reporting in Active Duty Service Members With a History of Mild to Moderate Traumatic Brain Injury.

Objective: Physical therapy following traumatic brain injury (TBI) can be negatively impacted by psychological symptoms, atypical symptom reporting, and response bias. We examined rates of Symptom Validity Test (SVT) failure in active duty military service members with a history of mild-moderate TBI and its impact on gait speed.

Setting: Intensive Outpatient Program at the National Intrepid Center of Excellence at Walter Reed National Military Medical Center.

Participants: Participants were 84 active duty service members with a history of mild-moderate TBI classified as SVT pass ( n = 49) or SVT fail ( n = 35).

Design: Retrospective study.

Main Measures: Overground preferred and fast walking speed as well as Computer Assisted Rehabilitation Environment (CAREN) gait speed were recorded. Participants completed the Neurobehavioral Symptom Inventory and the Validity-10 was used to assign patients into the SVT pass and SVT fail groups. Gait speed metrics were compared across these groups and test operating characteristics were calculated.

Results: Approximately 42% of the sample was classified into the SVT fail group. All 3 gait speed measures were significantly slower in the SVT fail group than in the SVT pass group ( P s < .001, d s = 0.60-0.80). Gait speed cutoffs for screeners or indicators of atypical reporting were identified.

Conclusions: The potential for response bias is a critical area for the clinician to consider when conducting physical therapy evaluations. Participants in the SVT fail group had slower walking speed on all 3 measures assessed. Several useful cutoffs were identified to serve as screeners or indicators of SVT failure, though these preliminary findings have limitations and need to be replicated.