Abstracts

Rationale: Status epilepticus (SE) is a failure of seizure termination and is a life-threatening neurologic emergency. The 2015 International League Against Epilepsy (ILAE) classification of SE distinguishes non-convulsive SE (NCSE) from SE with prominent motor phenomena such as convulsive SE (CSE). In addition, the ILAE revised the definition of CSE in 2015 as “continuous clinical seizure activity for ≥5 min and/or ≥2 discrete seizures without interictal return to baseline.” The previous definition used a 30-minute time window. The objectives of this study were to describe the epidemiology (incidence and mortality) of SE, particularly CSE, in the US population, and to evaluate the associated burden of illness (recurrence, healthcare utilization and costs). Methods: A systematic review including literature and pragmatic searches was conducted. Literature searches were performed using MEDLINE, Embase, BIOSIS and Web of Science from inception to February 2019. Pragmatic searches of the grey literature were carried out using Google, Google Scholar, conference proceedings, and the Clinicaltrials.gov website to identify additional sources. Only US-based studies or multinational studies reporting US data of interest were included. Case reports/series, non-clinical studies and phase I-II trials were excluded. Results: In total 57 publications were included. Incidence of all age SE in the US ranged from 18.3 (1965-1984) to 41 per 100,000 person-years (1989-1991). Incidence of all age CSE rose from 3.5 (1979) to 12.5 (2010) per 100,000 person-years. Incidence of CSE was higher in patients aged <5 years and >75 years than in the overall patient population (7.5 and 22.3 vs 6.2 per 100,000 person-years). SE recurrence at one and two years was 13.1% and 20.3%, respectively.SE mortality varied from 21% over 30 days to 31.2% over ten years. For CSE, two studies reported similar in-hospital mortalities (9.2% and 10.7%), and a third reported a 60-day mortality rate of 17.8%. Children (<=21 years) had lower CSE in-hospital mortality than adults (0.7-3.0% vs 3.5-14.0%). All age CSE 30-day mortality decreased over time (4.7% in 1991 to 3.2% in 1998; p=0.004). In-hospital mortality remained stable in adults (4.6% in 1991-1992 and 4.3% in 2001-2002), except in urban teaching hospitals where a decrease was observed (7.3% in 1991-1992 to 4.5% in 2001-2002; p<0.001). From 1979-2010, SE accounted for 0.07% of all US hospital admissions. For all age CSE, the 30-day all-cause readmission rate was 14% in 2013 (20% in children). Median health care costs related to SE admission were approximately $14,500 per adult and $8,000 per child (2018 cost estimate). Conclusions: There is a lack of recent data on the epidemiology and health care burden associated with SE. Reports of SE incidence in the USA are highly variable with most pre-dating the 2015 ILAE definition of SE, and new therapies, not available at the time of these reports, are likely to have an influence on these estimates. However, the available data suggest a high burden of illness in SE. Funding: Study funded by Shire Development LLC, a Takeda company.