Abstracts

Rationale: To evaluate the long term effectiveness of clobazam in children with intractable epilepsy, using treatment persistence (retention rate) without additional therapy as the primary outcome measure, and to assess the impact of concomitant AEDs on retention rate. Methods: This is a retrospective cohort study conducted at two U.S. comprehensive pediatric epilepsy centers. Children ages 0 to 21 years who initiated clobazam for the first time between 1/1/2012 and 1/1/2017, outside of a clinical trial, with at least one follow up visit were included. Kaplan-Meier survival curves were generated for time to CLBZ discontinuation, and time to CLBZ failure, defined as discontinuation of CLBZ or addition of another antiepileptic therapy. The impact of use of concomitant valproate (VPA) and patient and epilepsy characteristics were evaluated using Cox regression. Results: Queries of the electronic medical records found 1601 potentially eligible patients. For this work in progress, 400 charts were reviewed resulting in 196 eligible patients (97 female) included in the analysis cohort. Median age at CLBZ initiation was 10 years (IQR 5-15). Fifty-six (30%)  had a diagnosis of Lennox Gastaut Syndrome (LGS). Median follow up was 31 months (IQR 18-45). Probability of CLBZ continuation was at 67% 12 months, and 53 % at 24 months. Median time to CLBZ discontinuation was 27 months. Probability of CLBZ success (continuation without addition of another therapy) was 44% % at 12 months, and 29 % at 24 months. Median time to CLBZ failure was 10.5 months. Diagnosis of LGS did not impact CLBZ success rate (HR 0.83, 95%CI 0.59-1.2, p=0.346). Concurrent treatment with VPA and/or the ketogenic diet were not associated with a change in success rate. Conclusions: This study provides observational evidence of treatment persistence of CLBZ in children with intractable epilepsy, using time to treatment failure (CLBZ discontinuation or increase/addition of other therapy) as the primary outcome measure, similar to treatment persistence of other AEDs in refractory childhood epilepsy populations.References:1 Kessler et al. Epilepsy Res. 2015;112:18-26.2 McGinnis and Kessler. Epilepsia. 2016;57(9):1416-1425. Funding: None