Comparing two models of performance validity assessment in patients with Parkinson's disease who are candidates for deep brain stimulation surgery.

Utility of standalone and embedded performance validity tests (PVTs) as well as the decision-making algorithms used to reach clinical conclusions about credible and noncredible performance can be population specific. To better understand PVT utility in Parkinson's disease candidates for deep brain stimulation (DBS) we present on two aims: 1) establishing the frequency data of below-criterion responding for the Medical Symptom Validity Test and three embedded PVTs in a sample of 47 patients with Parkinson's disease, and 2) comparing the efficacy of two models for clinical-decision making regarding noncredible performance. Consistent with expectations from previous studies and desired specificity values, our retrospective analysis indicated that in this sample of presumably well-motived patients, the rate of below-criterion responding was less than 10% for all PVTs administered. Regarding our model comparison, we compared a typical PVT battery that required administration of a standalone measure in all cases against a recently proposed low risk algorithm that attempts to lower testing burden by relying more heavily on embedded PVTs with administration of a standalone measure only in the event of below-criterion performance on an embedded indicator. Results suggest that for patients with Parkinson's disease judged to be at limited risk for noncredible performance, a low risk PVT model may prove both more efficient and less prone to error than a more typical model. Implications for clinical decision-making are discussed, as are limitations of the study and its generalizability.