Validity and Utility of the Miller Forensic Assessment of Symptoms Test (M-FAST) on an Inpatient Epilepsy Monitoring Unit

As overreporting of symptoms threatens the integrity and utility of the neuropsychological evaluation, symptom validity test (SVT) usage has become a standard of practice. The Miller Forensic Assessment of Symptoms Test (M-FAST) SVT has been validated in various forensic contexts, though its utility in specific medical settings remains under-explored. The current study examined the validity and diagnostic utility of the M-FAST among 123 inpatient veterans on a long-term video electroencephalogram (V-EEG) epilepsy monitoring unit (EMU). Select scores from the Structured Inventory of Malingered Symptomatology and the Minnesota Multiphasic Personality Inventory-2-Restructured Form were combined into an SVT composite used as a criterion for validating the M-FAST with receiver operating characteristic (ROC) curves. A Student’s t -test revealed significantly higher total M-FAST scores among the symptom invalidity group compared to individuals with valid symptom reports (Cohen’s d = 1.24). An optimal M-FAST cut score of ≥ 5 was identified to detect symptom overreporting, with .65 sensitivity and .85 specificity (AUC = .82). However, ROC curve analysis indicated that the M-FAST had poor diagnostic classification accuracy for V-EEG-confirmed epilepsy (ES; n = 21) versus V-EEG-confirmed psychogenic non-epileptic events (PNEE; n = 46; AUC = .56). Although diagnostic utility of the M-FAST for PNEE versus ES was not supported within our sample, results demonstrate the validity of the M-FAST as an effective SVT in an EMU. Findings highlight that various cut scores may be considered to optimize detection of symptom overreporting in settings where comorbid physiological and psychological conditions may influence response validity.