Zack Z Cernovsky, James D Mendonça, Jack R Ferrari, Yves RJ Bureau
Objective: The Structured Inventory of Malingered Symptomatology (SIMS) is a test widely used by psychologists when testifying in insurance litigation. We evaluated the content validity of SIMS Low Intelligence scale (LI).Method: Three clinical psychologists with more than 35 years of experience each rated the content validity of all items of SIMS LI scale with respect to their capacity to separate malingerers from persons with genuinely impaired cognitive functioning after motor vehicle accidents (MVAs). Post-MVA factors endured by the latter such as post-concussion syndrome, persistent pain, pain related insomnia, and fatigue interfere with attentional focus and other aspects of cognitive performance. Furthermore, scores on the LI scale of 23 survivors of high impact MVAs were evaluated to estimate the rates of false positives. Results: The 3 raters concluded that none of the 15 items of SIMS LI scale appears suited to differentiate malingerers from real patients. Most of its items seem sensitive to post-MVA impairments such as the post-concussion syndrome and fatigue. Patients with more extensive cognitive impairment are likely to obtain higher scores on the LI scale and thus, falsely diagnosed as “malingerers” than those less impaired. Average LI score (4.8 points, SD=4.4) of the 23 injured survivors of high impact MVAs was within the “malingering” category and 65.2 %, were classified by SIMS LI scale as “malingerers.” It seems more plausible that their elevated LI scores reflect their post-concussion syndrome, chronic fatigue from pain, and pain related insomnia.Conclusions: None of SIMS LI items appears to have an adequate capacity to differentiate malingerers from real patients. Patients with post-MVA cognitive impairment are likely to be misclassified as “malingerers.