To evaluate the long-term effectiveness of clobazam (CLBZ) in children with epilepsy, using treatment persistence (retention rate) without additional therapy as the primary outcome measure.

This retrospective cohort study was conducted at two US comprehensive pediatric epilepsy centers. Children ages 0-21 years starting 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 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 concomitant valproate (VPA), and patient and epilepsy characteristics were evaluated using Cox regression.

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 LGS. Median follow-up was 31 months (IQR 18-45). Probability of CLBZ continuation was at 67% at 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. LGS diagnosis 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 did not impact success rate.

Treatment persistence of CLBZ is comparable to treatment persistence of other AEDs in refractory childhood epilepsy populations.