High elevation rates of the Structured Inventory of Malingered Symptomatology (SIMS) in neuropsychological patients.

The current study examined characteristics of the Structured Inventory of Malingered Symptomatology (SIMS) in a sample of 110 patients at an adult neuropsychology clinic. Subjects with especially high or low suspicion of invalid reporting were identified based on clinician-completed questions. SIMS elevation rates were examined at different cutoffs and between these groups and were correlated with other indicators of validity. High rates of SIMS elevations were found at the standard cutoff (>14) for the total sample (45.5%), low suspicion cases (24.4%), and high suspicion cases (95.7%). Other indicators of invalidity were low (secondary gain = 8.5%, clinical suspicion of exaggeration in interview M = 2.37/5, medical records concerning for invalidity = 2.4%, mixed/poor performance validity = 6.1%). Elevations correlated with clinician concern for over-reporting in interview, subject-reported cognitive concern ( = -.610) and psychological measures (BDI-II = -.602, PROMIS = -.409) but not with neuropsychological memory tests or performance validity measures (all > .23). The SIMS should be interpreted with caution, as elevations appeared largely related to cognitive concern and psychiatric distress rather than true malingering. A cutoff of > 16 could be used in neuropsychological populations, although this is still of modest specificity.