Abstracts

Rationale: The effects of seizure clusters in epilepsy patients can be critical and include increased health care utilization and adverse outcomes. The purpose of this study was to investigate clinical factors associated with seizure clusters in pediatric patients. Methods: This was a retrospective study of baseline data obtained in an ongoing prospective observational study conducted at two tertiary epilepsy centers. Patients 1 month to 18 years of age with a documented diagnosis of epilepsy were included. Those with psychogenic/non-epileptic seizures, epileptic spasms, or a very high baseline frequency of seizures (more than one seizure per hour) were excluded. We defined clusters as two or more seizures in 24 hours (day clusters). Patients were categorized into three groups based on their reported seizure frequency in the year prior to enrollment: 1- “Prior clusters”: Patients reporting at least one seizure cluster, 2- “Active epilepsy”: patients reporting seizures but without clustering, and 3- “Seizure Free”: patients who were seizure free during the prior year. Results: Of the 251 patients enrolled, 53.8% were female, and the median age was 10 years (IQR: 7-14). Overall, 70.1% identified as white, 10.8% as Black/African American, 4.4% as Asian, and 14.7% unknown. Median age at seizure onset was 2 years (IQR: 0-5). The median number of previously trialed anti-epileptic drugs (AEDs) was 1 (IQR: 0-3). 86 patients (34.3%) were categorized in group 1 (prior clusters), 86 (34.3%) in group 2 (active epilepsy), and 79 (31.4 %) in group 3 (seizure free). Patients in the prior clusters group were younger than the other two groups (Table 1). Age of seizure onset was not different amongst the three groups (Kruskal-Wallis rank test, p=0.16). Median baseline seizure frequency per month was 28 (IQR: 4-84) in the prior clusters group, and 0.17 (IQR: 0.083-2.42) in patients with active epilepsy without clusters (p < 0.001). Specific risk factors for seizures, including family history of epilepsy, mesial temporal sclerosis, dysplasia/neuronal migration disorder were not different among the three groups (Table 1). Patients with prior clusters had failed more AEDs on average (Table 1). History of status epilepticus was more frequent in groups 1 (40.2%) and group 2 (50%) compared with group 3 (22.5%) (p= 0.003). Overall, 59.3% of patients (149/251) had a rescue plan, including 59.3% (51/86) of the “Prior clusters” group, and 78.1% of (64/82) patients with a history of status epilepticus.In the multivariate logistic regression analysis, a history of seizure clusters was associated with younger age, higher seizure frequency at baseline, and greater number of failed AEDs (Table 2). Conclusions: Seizure clusters are common in pediatric epilepsy patients. Younger age and refractory epilepsy were associated with seizure clusters. Results have further implications for best selection of patients for individualized seizure action plans and seizure monitoring devices. Funding: This study was supported by Upsher-Smith Laboratories.