Objective: Data from Lange and colleagues' (2013) prospective analogue simulation study were reanalysed to investigate the utility of a new embedded measure of symptom exaggeration, the Neurobehavioral Symptom Inventory (NSI) Validity-10 index. Method: Participants were 85 Australian undergraduate students who were allocated to one of three experimental conditions: Control (i.e., honest responding, n = 24), Feign Postconcussive Disorder (PCD; n = 29), and Feign Posttraumatic Stress Disorder (PTSD; n = 32). Participants completed the NSI as part of a larger test battery. Results: Participants who feigned PCD or PTSD had significantly higher NSI total scores (both p < .01; d = 3.71 and d = 2.33, respectively), and higher Validity-10 scores (more exaggeration; both p < .01; d = −3.1 and d = −1.75, respectively) compared to controls. There were no significant differences between the feigning groups for the NSI total or Validity-10 scores (both p >.05). With the data collapsed across feigning conditions, the optimal Validity-10 cut-off score to detect symptom exaggeration was ≥ 10. This cut-off score resulted in moderate sensitivity (.75) and negative predictive power (.88) and high specificity (1.0) and positive predictive power (1.0). Conclusion: The optimal cut-off score for the Validity-10 was lower than previously reported, but not dissimilar to the cut score identified in one other study (i.e., ≥ 13; Lange et al., in press). Although the diagnostic efficiency of this cut-off score is encouraging, this index has not yet been widely evaluated and it should not be used for diagnostic purposes. With further evaluation, it could prove to be a useful inclusion in a screening process.
PROFESSIONAL ISSUES: EFFORT AND MOTIVATION
An Analogue Investigation of the Utility of the Validity-10 index for the Neurobehavioral Symptom Inventory
K Sullivan, R Lange, S Edmed; PROFESSIONAL ISSUES: EFFORT AND MOTIVATION
An Analogue Investigation of the Utility of the Validity-10 index for the Neurobehavioral Symptom Inventory. Arch Clin Neuropsychol 2015; 30 (6): 587-588. doi: 10.1093/arclin/acv047.268
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