Counting seizures: The primary outcome measure in epileptology from the patients' perspective

Purpose: Patient-reported seizure counts represent a key outcome measure for individual treatments and clinical studies in epileptology. Video-EEG based research, however, demonstrated lack of validity due to underreporting. Here we examined the practice of keeping seizure diaries and the patients' attitudes toward seizure counting.

Methods: Anticipating a low return rate, a comprehensive survey was mailed to 1100 adult outpatients. Besides methods and reasons to document or not to document seizures, the questionnaire addressed clinical, personality and sociodemographic characteristics as well as the subjective experience of seizures.

Results: Questionnaires from 170 patients (15%) could be included in our analysis. Patients estimated to be aware of 5.3 out of 10 daytime seizures (nocturnal seizures: 2.6) while they supposed that relatives/colleagues noticed 7.1 (nocturnal: 4.6). Almost two-thirds of the patients reported to keep a seizure diary with a self-estimated documentation rate of 8.7 out of 10 noticed daytime seizures (nocturnal: 7.7). Documenters and non-documenters showed only marginal group differences with regard to clinical, personality and sociodemographic characteristics. Importantly, patients were more committed to keep a seizure diary when they judged it to be relevant for clinical treatment decisions.

Conclusion: Patients appear to know that they underreport seizures. According to their view, seizure unawareness as induced by seizures themselves seems to be a more important factor than omitting documentation of noticed seizures. Thus, the potential to improve the validity of seizure diaries of electronic devices which facilitate documenting noticed seizures appears limited.