Clinical identification of psychogenic nonepileptic events using combinations of psychological tests in a veteran sample.

Objective: Patients with psychogenic nonepileptic events (PNEE) exhibit heterogenous symptoms and are best diagnosed with long-term video-electroencephalogram (vEEG) data. While extensive univariate data suggest psychological tests may confirm the etiology of PNEE, the multivariate discriminant utility of psychological tests is less clear. The current study aggregated likelihood ratios of multiple psychological tests to evaluate incremental and discriminant utility for PNEE.

Methods: Veterans with vEEG-diagnosed PNEE (n = 166) or epileptic seizures (n = 92) completed self-report measures and brief neuropsychological evaluations during the 4-day vEEG hospitalization. Receiver operating characteristic (ROC) curves identified discriminating psychological tests and corresponding cut-scores (0.85 minimum specificity). Likelihood ratios from the remaining cut-scores were sequentially linked using the sample base rate of PNEE (64%) and alternative base rates (10%, 20%, 30%, 40%) to estimate posttest probabilities (PTP) of test combinations.

Results: The Health Attitudes Survey, Health History Checklist, and Minnesota Multiphasic Personality Inventory-2-Restructured Form scales FBS-r, RC1, MLS, and NUC were identified as discriminating indicators of PNEE. Average PTPs were ≥90% when three or more indicators out of six administered were present at the sample base rate. Regardless of PNEE base rate, PTP for PNEE was ≥98% when all discriminating indicators were present and 92-99% when five of six indicators administered were present. PTPs were largely consistent with observed positive predictive values, particularly as indicators present increased.

Significance: Aggregating psychological tests identified PNEE with a high degree of accuracy, regardless of PNEE base rate. Combining psychological tests may be useful for confirming the etiology of PNEE.