Utility of the Standardized Assessment of Concussion (SAC) to Detect Insufficient Effort in Independent Medical Examinations and Civil Litigation Cases

Abstract

Objective: The Standardized Assessment of Concussion (SAC) is a standardized mental status screening instrument initially developed for assessment and tracking of concussion symptoms in athletes. The purpose of the current study was to validate the utility of the SAC as an embedded screening measure for insufficient effort in independent medical examinations (IME) and personal injury cases. Method: A known-groups design was used to examine the SAC’s utility for the detection of insufficient effort in 75 de-identified private IME and civil litigation evaluations. Initial classifications of insufficient effort were made independently of SAC scores, on the basis of having two or more scores falling below established cut-offs on previously validated neuropsychological measures. Results: Results suggest that the total score on the SAC significantly distinguishes effortful respondents from those exhibiting insufficient effort. Empirically derived cut-off scores yielded adequate sensitivity (.62–.95) and negative predictive power (.93–.97). Conclusions: While optimal cut-off scores depend upon intended use, our data suggest that the SAC is useful as a potential screener for insufficient effort, after which one can employ additional measures to rule out false—positives. Further research is required before cut-off scores can be recommended for clinical use.

Keywords:

• Malingering
• Insufficient effort
• Neuropsychology
• IME
• Civil Litigation
• Standardized assessment of concussion (SAC).

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

¹ Others (e.g. Reznek, 2005) have argued that for a diagnosis of malingering—a “damning diagnosis” (Reznek, 2005)—one would choose a test with the highest possible positive predictive validity, such that no honest responders are misclassified by the test. Of course, the trade-off is the failure to identify some malingerers. We do not disagree with this position when the purpose of the evaluation is solely to diagnose malingering. If the goal is to maximize overall accuracy in evaluations, however, one would prefer to catch all malingerers and rule out false positives, in which case a test (or cut-off score) yielding high NPP is preferred. The caveat, of course, being that the clinician must remain aware that a screener is not diagnostic and should never interpret a positive score on a screener as diagnostic.

² We anticipate a concern among clinicians about our implication that a “pass” on the SAC should satisfactorily “rule-out” malingering. However, if an individual passes a malingering screen that has a very high NPP, administering additional malingering measures increases the risk of false positives (e.g. Frederick & Bowden, 2009; McGrath, 2008).