Validation of the Symptoms of Post-Concussion Syndrome Questionnaire as a Self-Report Symptom Validity Test: A Simulation Study

Symptoms of post-concussion syndrome (PCS) can occur after a mild traumatic brain injury (mTBI). Whilst specific neuropsychological tests can be used to determine cognitive disturbances, there is a reliance on the use of self-report measures to record the presence and severity of other PCS symptoms. Self-reported symptoms can be subject to over report and exaggeration, particularly in individuals involved in litigation (Mittenberg, Patton, Canyock & Condit, 2002; Larrabee, 2003).
Paper one investigated the research evidence relating to what is known about the validation of self-reported symptoms of PCS. A total of nine papers were identified and appraised, the findings were synthesised according to the following topic areas: performance validity test outcomes and symptom reporting, the application of PCS self-report measures as symptom validity tests (SVTs), and the application of new and existing SVTs. Paper two followed from a recommendation to investigate a new measure that involved the endorsement of both genuine symptoms and atypical symptoms of PCS. This paper aimed to explore the utility of the Symptoms of Post-Concussion Syndrome questionnaire (SPCS). A simulation design was employed using control participants instructed to respond genuinely, and participants instructed to malinger. An optimal cut off score of >25 was established for the measure which produced promising diagnostic classification statistics (sensitivity .90, specificity 1.00, positive predictive power = 100%, negative predictive power = 93.75%). Further validation of the proposed cut off score with a clinical sample is required. Finally, paper three provides a reflective account of the process of completing this thesis, and a discussion of the challenges that were encountered along the way.