The Structured Inventory of Malingered Symptomatology (SIMS) is a psychological assessment instrument designed to screen for possible exaggeration or feigning of cognitive impairment and psychiatric disorders.
The SIMS Manual recommends a cut off score of 14 to indicate the possibility of significant exaggeration and feigning. However, subsequent research has demonstrated that this cut score produces high false positive rates, e.g., 36% in a study with personal injury litigants and disability claimants.1
Whatever you do, do NOT…
… state that a veteran is feigning or malingering based on a SIMS score alone. As the test publisher states in their computer-generated interpretative report:
The SIMS is not intended to serve as a diagnostic tool for feigning in isolation. Individuals identified as potential malingerers through the use of the SIMS should be referred for more extensive assessment. A determination of feigning should be made in the context of a comprehensive evaluation only, whereby multiple sources of data (e.g., psychosocial, psychiatric, and medical history; clinical interview; comparison of subjective reports of symptoms to objective information and observations; results from feigning-specific and psychological inventories) as well as multiple assessment devices (e.g., structured interviews, performance based tests) are employed in order to provide convergent and corroborative data in making a definitive classification of feigning.
Although the determination of feigning is dependent upon the discrimination between actual versus feigned or exaggerated symptoms, it does not preclude the presence of another disorder. As such, the suggestion of probable feigning using the SIMS should not negate the possibility of genuine disability or disorder. [emphasis added]
Screening vs. Test Battery
QUESTION: What cut score should C&P psychologists use during psychological claim exams?2
ANSWER: It depends on why you administer the SIMS. If you give the SIMS to screen for possible exaggeration or feigning, then you want to use a cut score with fairly good sensitivity, and you can accept somewhat lower specificity. (Of course, this approach assumes that you will conduct a more in-depth assessment for possible exaggeration/feigning if the veteran’s SIMS score is above the cut-off.)
On the other hand, if you administer the SIMS as part of a ‘test battery’,3 then you want high specificity.
SIMS as a Screening Instrument
In a recent systematic review and meta-analysis, the authors recommend a cut score of >16 for screening purposes, or, alternatively “combined cutoffs” of >16 and >19, with “… scores from 17 to 19 as indicating possible feigning, or relatively mild feigning. Follow-up testing is warranted.”4 [emphasis in original]
The >19 cut score is “[r]ecommended when the SIMS is employed as part of a test battery that is utilized for conclusive assessment of feigned psychopathology. It yields lower sensitivity, but higher specificity (reduced risk of false-positive classification).”5 (I encourage you to not use >19 as the cut score for a Psych C&P exam test battery – see below.)
If you want to use the SIMS as a screening instrument, a >16 cut score seems reasonable, i.e., scores of 17 and above should trigger a more comprehensive assessment of possible exaggeration/feigning.
SIMS as Part of a Test Battery
When using the SIMS as part of a test battery designed to comprehensively assess for possible exaggeration/feigning, the authors of the systematic review article state that a >24 cut score is “[o]nly recommended when the SIMS is employed as part of a test battery for conclusive assessment in populations with particularly heightened SIMS scores due to genuine psychopathology (e.g., schizophrenia, intellectual disability).”6
While veterans presenting for a Psych C&P exam generally do not suffer from schizophrenia or low intellectual ability, I nonetheless recommend (for a exaggeration/feigning test battery) using a cut score of 24 (or higher) for three (3) reasons.
First, some genuine psychiatric patients in SIMS research studies had scores of 25 to 34. In the systematic review article,7 the mean SIMS score for genuine (not exaggerating/feigning) patients across several different studies (n = 742) was 16.1 with a standard deviation of 8.8. Assuming a normal distribution of scores, this means that about 16% of the genuine patients scored at or above 25 (mean + 1.0 sd = 24.9), and approximately 2% scored at or above 34 (mean + 2.0 sd = 33.7).
Plus, we know from prior research, primarily with the MMPI-2, that genuine PTSD patients tend to overreport psychiatric symptoms to a significant degree.8,9,10
Second, in keeping with the equipoise principle in veterans law11 C&P psychologists should err on the side of cut scores that might seem too conservative, as opposed to choosing a cut score on the edge.
Third, if one uses the SIMS along with other symptom validity tests, e.g., the Personality Assessment Inventory (PAI), Minnesota Multiphasic Personality Inventory-2 Restructured Form (MMPI-2-RF), Miller Forensic Assessment of Symptoms Test (M-FAST ), Structured Inventory of Reported Symptoms (SIRS ), etc., one must take into account several factors in order to accurately gauge the Positive Predictive Power (PPP) of the test battery as a whole.12,13
These factors include the:
- correlations between and among all the symptom validity tests (to determine independence of the measures);
- sensitivity and specificity for each test;
- the proportion of test results indicating significant exaggeration/feigning from the total of all SVTs administered, e.g., 2/4, or 3/5, etc.;
- estimated base rate (prevalence) of significant exaggeration/feigning in the population being evaluated (that could be the base rate for all veterans presenting for a Psych C&P exam (PTSD and other mental disorders); or, more specifically, the prevalence rate for veterans presenting for a PTSD C&P exam; or the base rate of significant exaggeration/feigning for veterans claiming depression secondary to Parkinson’s disease, etc.)
⇒ All of these points are discussed in the articles by Berthelson, et al. (2013)12 and Odland, et al. (2015).13
Other important considerations include:
- the extent to which the C&P psychologist has kept up with the scientific literature on evidence-based psychological assessment in general, and psychological disability evaluations with veterans in particular;
- the C&P psychologist’s willingness to hand-score test results when the standard scoring software does not do so, e.g., on the MMPI-2-RF, Ds-rf and F-r T-scores over 120, both of which demonstrate very high specificity and PPP, but are not scored via the standard MMPI-2-RF scoring software.
- whether the C&P examiner selects which SVTs he or she will administer a priori (including using a priori decision-trees) or on the fly.
1. Nick M. Wisdom, Jennifer L. Callahan, & Terry G. Shaw, Diagnostic Utility of the Structured Inventory of Malingered Symptomatology to Detect Malingering in a Forensic Sample, 25 Aʀᴄʜ. Cʟɪɴ. Nᴇᴜʀᴏᴘsʏᴄʜᴏʟ. 118, 122 (2010).
2. The Veterans Benefits Administration (VBA) recently began using the terms claim exam or VA claim exam instead of compensation and pension exam. See my previous post, 5 Lessons from VBA’s New C&P Exam Fact Sheets for more information.
3. Test battery is a traditional psychological term referring to a group of psychological tests administered to assess different facets of an individual’s cognitive functioning, personality, or behavior. In turn, a test battery is one part of an overall evidence-based psychological assessment, which involves multiple methods, e.g., structured diagnostic interviews, collateral interviews, record reviews, mental status exam, and psychological tests. In other words, a test battery is a component of evidence-based assessment, not the whole enchilada.
4. Alfons van Impelen, Harald Merckelbach, Marko Jelicic, & Thomas Merten, The Structured Inventory of Malingered Symptomatology (SIMS): A Systematic Review and Meta-Analysis, 8 Cʟɪɴ. Nᴇᴜʀᴏᴘsʏᴄʜᴏʟ. 1336, 1357 (2014).
7. Id. at 1352.
8. Lee Hyer et al., Vietnam Veterans: Overreporting Versus Acceptable Reporting of Symptoms, 52 J. Pᴇʀs. Assᴇss. 475 (1988).
9. B. Christopher Frueh et al., Apparent Symptom Overreporting in Combat Veterans Evaluated for PTSD, 20 Cʟɪɴ. Psʏᴄʜᴏʟ. Rᴇᴠ. 853 (2000).
10. C. Laurel Franklin et al., Differentiating Overreporting and Extreme Distress: MMPI-2 Use with Compensation-Seeking Veterans with PTSD, 79 J. Pᴇʀs. Assᴇss. 274 (2002).
11. Gilbert v. Derwinski, 1 Vet. App. 49 (1990).
12. Lena Berthelson et al., False Positive Diagnosis of Malingering Due to the Use of Multiple Effort Tests, 27 Bʀᴀɪɴ Iɴᴊ. 909 (2013).
13. Anthony P. Odland et al., Advanced Administration and Interpretation of Multiple Validity Tests, 8 Psʏᴄʜᴏʟ. Iɴᴊ. L. 46 (2015).