The Mild Brain Injury Atypical Symptoms (mBIAS) scale in a mixed clinical sample.

INTRODUCTION: The Mild Brain Injury Atypical Symptoms (mBIAS) scale was developed as a symptom validity test (SVT) for use with patients following mild traumatic brain injury. This study was the first to examine the clinical utility of the mBIAS in a mixed clinical sample presenting to a Department of Veterans Affairs (VA) neuropsychology clinic.

METHOD: Participants were 117 patients with mixed etiologies (85.5% male; age: M = 39.2 years, SD = 11.6) from a VA neuropsychology clinic. Participants were divided into pass/fail groups using two different SVT criteria, based on select validity scales from the Minnesota Multiphasic Personality Inventory-2 (MMPI-2): first, Infrequency Scale (F) scores: (a) MMPI-F-Fail (n = 21) and (b) MMPI-F-Pass (n = 96); and, second, Symptom Validity Scale (FBS) scores: (a) MMPI-FBS-Fail (n = 36) and (b) MMPI-FBS-Pass (n = 81).

RESULTS: The mBIAS demonstrated good internal consistency, and each item contributed meaningfully to the total score. At a symptom exaggeration base rate of 35%, an mBIAS cutoff of ≥11 was optimal for screening symptom exaggeration when groups were classified using both F and FBS scales. This cutoff score resulted in very high specificity (.89 to .94); moderate-high positive predictive power (.71 to .75) and negative predictive power (.72 to .79); and low-moderate sensitivity (.31 to .57). At all base rates of probable somatic exaggeration, a cutoff of ≥16 resulted in perfect specificity and positive predictive power, but very low sensitivity.

CONCLUSIONS: The mBIAS has potential for use in samples outside of mild traumatic brain injury. In settings where the symptom exaggeration base rate is 35%, a cutoff of ≥11 may be used as a "red flag" for further evaluation, but should not be relied on for clinical decision making. At all base rates of probable somatic exaggeration, psychologists with patients who score ≥16 can be confident that those patients were exaggerating. Importantly, however, this cutoff may fail to identify a large proportion of patients who are exaggerating.