The effects of adjunctive topiramate therapy on seizure severity and health-related quality of life in patients with refractory epilepsy—a Canadian study

Although reduction in seizure frequency is the most common endpoint used to assess the antiepileptic efficacy, seizure frequency alone does not provide a complete picture of effectiveness, particularly in patients with refractory epilepsy. The aim of our study was to assess the effects of topiramate on seizure severity and health-related quality of life (HRQL), in addition to standard efficacy measures, in an open, multicentre, 6-month trial of patients with epilepsy uncontrolled on antiepileptic drugs other than topiramate. Two hundred and nine patients were enrolled and received topiramate for up to 6 months (initiated at 50 mg/day and titrated to a recommended dose of 200-400 mg/day) in addition to existing medication. The median reduction in seizure frequency from baseline to the post-titration period was 40.9% ( P< 0.0001). Patients also demonstrated a mean reduction in the Liverpool Seizure Severity Scale (LSSS) of 5.3 ( P< 0.0001), which was considered clinically significant. Statistically significant changes in HRQL were not observed with the SF-36, a generic measure. Tolerability of antiepileptic medication was good, with a low incidence of cognitive adverse events. The results indicate that topiramate significantly reduces seizure severity---an important aspect of HRQL---when administered as adjunctive therapy to anticonvulsant therapy.