B - 138 Factors Influencing Performance Validity Test (PVT) Performance in a Clinical Multiple Sclerosis Sample

Abstract Objective Performance Validity Test (PVT) failure, originally designed to assess malingering in forensic settings, is remarkably common in the clinical setting. Though there are potentially numerous explanations for PVT failure, there is a paucity of research investigating its frequency, and contributing factors, in patients with neurological disorders. We aimed to identify factors associated with PVT failure among patients with multiple sclerosis (MS). Method A hierarchical logistic regression was performed on a dataset containing neuropsychological assessment results of 32 males (23.5%), and 104 females (76.5%) with MS (N = 106, Mean age = 47.9) to evaluate associations between depression (Patient Health Questionnaire-9, PHQ-9), anxiety (Hospital Anxiety and Depression Scale, HADS-Anxiety) (step 1), fatigue (Fatigue Scale of Motor and Cognitive Functions, FSMC) (step 2), age/years of education (step 3), and PVT failure (Test of Memory Malingering, TOMM score < 45). Results The final model was significant and explained 40.8% of the variance in TOMM failure (χ2(6) = 21, p = 0.002). The odds of PVT failure increased by 22.1% (p = 0.04) for every 1 unit increase in z-score on the PHQ-9. The odds of PVT failure increased by 66.3% for every 1 point increase in total Cognitive Fatigue (p = 0.01). Age, education, HADS-Anxiety, and Motor-Fatigue were not significantly associated with TOMM failure. Conclusion It is commonly assumed that neurology patients who fail PVTs are seeking secondary gain (e.g., disability). This study provides some support for the hypothesis that psychological factors, such as depression and cognitive fatigue, may significantly contribute to PVT failure in some clinical populations.