Budget impact analysis of cenobamate, a novel adjunctive therapy for the treatment of drug resistant focal onset seizures, from the Belgian healthcare payer perspective.

Cenobamate has recently been introduced as new anti-seizure medication (ASM) for patients with focal onset seizures (FOS) who are insufficiently controlled despite the use of three previous ASMs. To date, few evaluations have addressed the budgetary impact for the healthcare payer of add-on ASMs in patients with drug-resistant epilepsy (DRE). This study aims to assess the budgetary implications for the Belgian health insurer, the National Institute for Health and Disability Insurance (NIHDI), if cenobamate were reimbursed for the adjuvant treatment of FOS in adults with DRE. A prevalence-based budget impact model (BIM) was developed from the perspective of the Belgian NIHDI, considering all direct healthcare costs over a three-year time horizon. A standardized expert elicitation process with experienced epileptologists was conducted to collect data on Belgian clinical practice. Source data uncertainty impact was investigated through a one-way sensitivity analysis (OWSA). Over a three-year period, considering the cumulative drug costs of cenobamate, replacement of other third-generation ASMs, and savings generated at medical cost level, the introduction of cenobamate as adjunctive treatment for the target population was estimated to reduce the NIHDI budget by -€8 105 616. The robustness of these savings was confirmed through an OWSA. The savings at medical cost level fully offset the impact of cenobamate on the drug budget, leading to an overall healthcare budget saving of -€8 105 616 for NIHDI. This favourable outcome is largely due to cenobamate's high efficacy reflected in its high response rate and significant effect on reducing seizure frequency.