Abstracts

Rationale: Seizure clusters (SC) are acute episodes of consecutive seizures that occur within a short period of time with a patient regaining consciousness during the inter-ictal period. SCs are a seizure emergency, and patients with SCs are considered to be at risk for status epilepticus and increased mortality. This is expected to translate into poorer quality of life and increased economic burden in these patients. Although the burden of SC has been assessed in non-systematic reviews, this burden is under-recognized and there is a need to systematically assess the clinical, humanistic, and economic burden associated with SCs. Methods: A systematic search of the literature on Embase.com, which includes the PubMed and Embase databases, was conducted. Supplementary searches included keyword-based searches in PubMed, Google and Google Scholar, and bibliographic searches. Searches were restricted to articles in English published after 2000. All identified articles were screened using a 2-step process (title/abstract followed by full-text screening). Articles reporting data on clinical, humanistic, or economic burden of SCs were included, and the data extracted and analyzed. Results: The rate of SC within epilepsy outpatients was 3-57% (Fig. 1). The rate was higher in prospective studies. During a cluster episode, the time between seizures decreased from 131 minutes (between 1st and 2nd seizure) to <15 minutes (4th and 5th). The incidence of status epilepticus in SC patients (15-40%) was higher than in non-SC patients (6-27%). SC was associated with more severe epilepsy (high baseline seizure frequency, history of status epilepticus, and higher risk of having failed 2 or more anti-epileptic drugs). The mortality rate ranged from ~2% over 1 year to ~19% over 37 years. Overall quality of life in SC patients was lower than in seizure-free epilepsy patients. SCs negatively affected patients’ ability to drive (73% of patients), independence (67%), and travel (59%). Patients’ SCs adversely affected their caregivers in mood (55% of caregivers), travel (52%), vacation (52%), and productivity (48%). About 30% of SC patients used an emergency room over 1 year. Seizure-related hospitalization was more common in SC compared to non-SC patients (odds ratio 5.3). SCs adversely affected patients’ productivity (69%); most of these patients had experienced a seizure at work (62%), or stopped working for some time (53%) due to SCs. Conclusions: SCs are common among patients with epilepsy. Results of this analysis suggest that patients with SC have a higher risk of status epilepticus and poorer quality of life and warrant physicians’ attention to identify SC patients for treatment. Whilst the data on humanistic and economic burden are limited in this under-studied population, it is clear that SCs not only affect the quality of life of both patients and caregivers, but also significantly impact their work productivity (and cost of care). Funding: UCB Pharma-sponsored