Abstracts

Rationale: Clobazam is an efficacious medication for the treatment of epilepsy, with seizure freedom rates ranging from 10-60% at doses of 0.5-2 mg/kg/d for durations up to two years in pediatric studies. While efficacy has been demonstrated in patients with generalized and partial epilepsy, limited data exists regarding the efficacy for specific seizure types. We examined the efficacy of clobazam in a cohort of pediatric and young adult patients seen at a single US pediatric epilepsy center and compared response based on patient age, clobazam dose, and seizure type. Methods: We retrospectively reviewed the medical records of patients treated with clobazam for refractory epilepsy at Cook Children s Medical Center since 1/2007. Patients with < 2 months follow-up were excluded. Data abstracted included age at initiation, seizure type, clobazam dosing (mg/kg/d) and seizure frequency at initiation and last follow-up. For each patients seizure types, outcome was determined at last visit post-treatment initiation and categorized as >90% reduction, >50% reduction, or < 50% reduction in seizure frequency. For the purposes of this analysis, outcome was then dichotomized to >50% and <50% seizure reduction and compared versus age at initiation, seizure type, and clobazam dose at last visit (categorized as <1mg/kg/d or > 1mg/kg/d).Results: Seventy-five patients were treated with clobazam during the inclusion period. Two discontinued the medication within 2 months secondary to lack of efficacy and 6 did not have adequate data at follow-up to assess response, leaving 67 (mean age 9.21y, range 0.62-22.04y) in the final cohort. All seizure types were represented, with complex partial (21%), myoclonic (20%), generalized tonic-clonic (17%), and atonic (15%) being most common. As many patients had multiple seizure types, 130 clobazam exposures were recorded. The average initial dose of clobazam was 0.95mg/kg/d (0.25-2.37mg/kg/d) and patients were on a mean of 2.76 concomitant AEDs (range 1-5). Twenty eight (42%) patients had a vagal nerve stimulator. At last followup (mean 14.4 months, range 2.1-48.2 months), 64 cases (49%) reported >50% seizure reduction, of which 47 (73%) experienced >90% seizure reduction. There were no significant differences in outcome when compared to age at initiation, seizure type, or clobazam dosing (Table 1).Conclusions: Clobazam is efficacious for the treatment of refractory childhood epilepsy with 49% of cases experiencing >50% reduction in seizure frequency at 1 year. Amongst patients with refractory epilepsy, those that respond to clobazam have remarkable seizure reduction with 73% of responders experiencing >90% reduction in seizure frequency. Clobazam is efficacious for all seizure types and no seizure type demonstrates more favorable response. Efficacy was not impacted by patient age or low versus high dosing in our cohort.