Subjective seizure counts by epilepsy clinical drug trial participants are not reliable

Self-reported seizure counts of patients with epilepsy guide individual treatment decisions and often represent the primary outcome measure of pharmacological trial in epileptology. The validity of these data has recently been challenged and the question is whether this applies to participants of clinical studies as well. Here we compared self-estimated seizure counting and documentation accuracy in participants and nonparticipants of former epilepsy clinical drug trials.

Adult participants (N=100) from a total of twenty-two phase II, III or IV clinical drug studies performed at our unit (2002-2015) underwent a structured telephone interview on self-estimated seizure awareness and seizure documentation accuracy. Data were compared to data from a recent study in adult epilepsy patients (N=132) who never participated in clinical trials and who answered the same questions (Blachut et al., Seizure 2015; 29:97-103).

Reported seizure frequencies, self-estimated seizure documentation accuracy (at best 46-53%), and the motivation for seizure-documentation were almost identical in both groups and no group effect was found except for higher self-reported awareness for nocturnal seizures in former study participants.

Epilepsy patients having participated in clinical drug trials report comparable erroneous seizure counts as do epilepsy patients in general. These data further corroborate the notion that most clinical trials in epileptology are based on inaccurate measures. Implications and possible solutions for patients, physicians, and research are discussed.