Abstracts

Rationale: Dravet syndrome (DS) is a rare early-onset epilepsy syndrome, characterized by a life-long form of developmental and epileptic encephalopathy (DEE) that typically begins in infancy and is marked by frequent, treatment-resistant seizures, significant developmental, motor, and behavioral impairments, and an increased risk of mortality and sudden unexpected death in epilepsy (SUDEP). Following FDA approval of the fenfluramine oral solution in June 2020 for epilepsy treatment in DS, our objective was to understand the medication persistence associated with the use of fenfluramine and compare it with valproate, a very commonly used medication among individuals with DS, and levetiracetam.

Methods: We analyzed patient-level US claims data to measure the 12-month persistence of fenfluramine, valproate, and levetiracetam following initial treatment. Individuals with prior/concomitant use of cannabidiol or stiripentol were excluded (fenfluramine use was also excluded for valproate and levetiracetam analysis). Individuals with DS were identified by International Classification of Diseases (ICD-10) diagnosis codes. Persistence was defined as the duration of continuous medication supply without a gap of more than 90 days. Kaplan-Meier survival analysis was used as an estimate and log-rank tests were used to compare persistence rates between the three treatment groups, with p < 0.05 as the threshold for significance. Censoring occurred at the end of the follow-up period.