Validating the modified Rivermead Post-concussion Symptoms Questionnaire (mRPQ)

Objective: Response distortions in the reporting of postconcussion symptoms can occur for many reasons. The Rivermead Post-concussion Symptoms Questionnaire (RPQ) was recently modified to include an embedded symptom validity indicator to test for atypical symptoms. The present study used a simulation design to investigate the psychometric properties of the modified RPQ (mRPQ). Method: 298 adult volunteers were randomised into three groups: honest responding (Controls, C) who reported actual, current symptoms; mild traumatic brain injury (mTBI) simulators (MS) who role played being injured, and; biased mTBI simulators (BMS) who role played being injured and were asked to bias (exaggerate) their response. The MS and BMS participants received instructions to support the simulation. All participants completed the mRPQ and a modified Neurobehavioral Symptom Inventory (mNSI). Results: A 2 x 3 mixed ANOVA with one within-group variable (Symptom type: Standard or Atypical) and one between-group variable (Instruction type: C, MS, BMS) found a significant two-way interaction (p < .05, eta p2 = .08). Conclusions: The BMS group had score elevations for both standard and atypical postconcussion symptoms; therefore, both symptom types should be considered when evaluating for biased responding. The mRPQ has promising psychometric properties and should be further developed.