Rogers's RS und SC Malingering Scales Derived from the SIMS

Background: Recent studies have shown conclusively that the Structured Inventory of Malingered Symptomatology (SIMS) lacks in content validity and criterion validity. Rogers, Robinson, and Gillard (2014) used an innovative statistical procedure to extract those SIMS items that could still usefully differentiate legitimate psychiatric patients instructed to respond honestly from those instructed to exaggerate symptoms. Their procedure resulted in their Rare Symptoms (RS) scale and Symptom Combination (SC) scale. The present study applied the RS and SC scales to patients injured in high impact motor vehicle accidents (MVAs) and also critically evaluates the content of these scales.

Method: An ANOVA was calculated to compare RS and SC data of 3 groups: (1) 23 survivors of high impact MVAs, (2) data collected by Rogers’s team on their 54 psychiatric patients instructed to respond honestly, and (3) data collected by Rogers’s team on their 53 psychiatric patients instructed to exaggerate symptoms.

Results and Discussion: All except four of the 23 post-MVA patients, i.e., 82.6%, obtained scores below Rogers’s cutoff of > 6, i.e., at a “non-malingering” level, on the RS scale and all except one of the 23, i.e., 95.7% scored below Rogers’s cutoff of > 6, i.e., at a “non-malingering” level, on the SC scale. Damaging evidence against the RS scale comes from the ANOVA: the RS scores of post-MVA patients did not differ significantly from psychiatric patients instructed to exaggerate: both groups scored significantly higher than psychiatric patients responding honestly. The SC scores of post-MVA patients did not differ significantly in the ANOVA from psychiatric patients responding honestly: both groups scored significantly lower than psychiatric patients instructed to exaggerate. Clinical content analysis of RS scale suggests irremediable flaws. A third of the RS items are logical or algebraic reasoning tasks on which patients with severe post-concussive symptoms and fatigue from insomnia (such as caused by persistent pain) could perform less well. Patients with extensive microvascular injuries and axonal shearing from their accident are more likely to score higher on the RS and be misclassified as “malingerers” than less injured persons. Another third of RS scale items lists delusional symptoms or those of thought disorder: psychotic patients are more likely to be branded as “malingerers” and deprived of pharmacotherapy. The SC scale is based on a precarious assumption that correlations among its symptoms remain the same across varied groups of genuine medical patients, regardless of the type and intensity of their own symptoms. Patients more severely disabled by their symptoms might be less consistent in their responses and thus more often misclassified as “malingerers” by the SC.

Furthermore, Rogers’s psychiatric sample on which the RS and SC scales were developed was diagnostically mixed, too heterogeneous, mainly diagnosed with PTSD (>77%) and/or mood disorders (>32%): this makes generalizations of RS and SC cutoffs to other diagnostic groups of psychiatric patients uncertain. Generalizations to yet other medical patients would need to be tested carefully, separately for each diagnostic group and on larger samples to satisfy APA requirements.