Use of multiple performance and symptom validity measures: Determining the optimal per test cutoff for determination of invalidity, analysis of skew, and inter-test correlations in valid and invalid performance groups

Abstract

Objective: Discrimination of patients passing vs. failing the Word Memory Test (WMT) by performance on 11 performance and symptom validity tests (PVTs, SVTs) from the Meyers Neuropsychological Battery (MNB) at per-test false positive cutoffs ranging from 0 to 15%. PVT and SVT intercorrelation in subgroups passing and failing the WMT, as well as the degree of skew of the individual PVTs and SVT in the pass/fail subgroups, were also analyzed.

Method: In 255 clinical and forensic cases, 100 failed and 155 passed the WMT, at a base-rate of invalid performance of 39.2%. Performance was contrasted on 10 PVTs and 1 SVT from the MNB, using per-test false positive rates of 0.0%, 3.3%, 5.0%, 10.0%, and 15.0% in discriminating WMT pass and WMT fail groups. These two WMT groups were also contrasted using the 10 PVTs and 1 SVT as continuous variables in a logistic regression.

Results: The per-PVT false positive rate of 10% yielded the highest WMT pass/fail classification, and more closely approximated the classification obtained by logistic regression than other cut scores. PVT and SVT correlations were higher in cases failing the WMT, and data were more highly skewed in those passing the WMT.

Conclusions: The optimal per-PVT and SVT cutoff is at a false positive rate of 10%, with failure of ≥3 PVTs/SVTs out of 11 yielding sensitivity of 61.0% and specificity of 90.3%. PVTs with the best classification had the greatest degree of skew in the WMT pass subgroup.

Keywords:

• Performance validity
• symptom validity
• multiple indicators
• diagnostic accuracy

Disclosure statement

Drs. Larrabee and Rohling provide expert consultation in litigated matters.