Treatment of epilepsy using newer antiseizure medications: A retrospective cohort study of prescription patterns in Sweden 2013-2022.

Objective: This study aimed to analyze the choice of newly introduced antiseizure medications (ASMs; brivaracetam, cannabidiol, cenobamate, fenfluramine, and perampanel) by age and sex, and the use of these ASMs in relation to regulatory approval.

Methods: Patients were identified with dispensation of any ASM subsequent to at least one health care contact due to epilepsy (International Classification of Diseases, 10th Revision: G40) during 2000-2022. Incidence rate ratios (IRRs) for starting a newly introduced ASM, retention rates, number of ASM treatments preceding the first dispensation of a new ASM and concurrent ASM treatments at first dispensed new ASM, and share of patients using new ASMs as adjunctive treatment were calculated.

Results: Three percent of all patients identified with epilepsy treatment during the period 2013-2022 used at least one new ASM. IRRs for ever being dispensed a new ASM differed between age groups for all ASMs except cenobamate. The corresponding IRRs associated with sex were insignificantly different from 1, except for cannabidiol; men were more likely to start using cannabidiol. One-year retention rates were between 42% (cannabidiol, men) and 64% (brivaracetam, men). The majority (70%) of patients had used >2 ASMs prior to the first dispensation of a new ASM, and a majority (98%) of patients were treated with another ASM at first dispensation of a new ASM (≤90 days before). Similarly, 82% of the patients who started using a new ASM did so as an adjunctive treatment (ASMs dispensed ≤90 days before and ≥90 days after first new ASM).

Significance: Our observations indicate that prescription patterns of the newer ASMs comply with the currently approved indications for the respective medications for a majority of patients (prevalence of brivaracetam as adjunctive treatment is somewhat lower). Retention on the dispensed medications are in line with what would be expected for adjunctive treatment of patients with drug-resistant epilepsies.