Examination of volunteer bias in research involving patients diagnosed with psychogenic nonepileptic seizures.

There is some evidence to suggest that the same personality and emotional features observed in patients diagnosed with psychogenic nonepileptic seizures (PNES) may be related to nonparticipation in studies aimed at determining the most effective interventions for treating this patient population. This study aimed to document the frequency with which patients referred to an epilepsy monitoring unit (EMU) for video/EEG telemetry who are diagnosed with PNES or epileptic seizures (ES) participate in survey research. Of the 139 patients approached, 16 patients declined and 23 produced invalid or incomplete surveys. There was no significant difference in participation rates between patients diagnosed with PNES and those diagnosed with ES. These findings argue against a volunteer bias in research involving PNES and suggest that the results of other studies with these patients generalize to the population as a whole.