OBJECTIVES: Tuberous sclerosis complex (TSC) is a rare disorder with substantial unmet need for treatment providing early, effective seizure control with an acceptable safety profile. This analysis evaluated the cost-effectiveness of add-on cannabidiol (Epidyolex^®; 100 mg/mL oral solution), versus placebo, in patients aged ≥2 years with treatment-refractory TSC-associated seizures managed with usual care.

METHODS: A cohort-level cost-effectiveness model with a lifetime horizon was constructed from the National Health Service (NHS) perspective in England. The model considers the impact of treatment on focal seizures, with impairment of consciousness/awareness, and generalised seizures. Health states were based on weekly seizure frequency and seizure-free days, with health state distributions derived using regression models utilising patient-level data from the GWPCARE6 trial (GWP42003-P; NCT02544763). Base-case analysis parameters included annual healthcare resource use, effect of treatment on development of TSC-associated neuropsychiatric disorders (both informed by Delphi studies of UK clinical experts and published literature), patient and caregiver utilities (estimated from a vignette study of the general population valued using time trade-off methodology), and TSC-related excess mortality rates, including sudden unexpected death in epilepsy (from published literature). Cannabidiol discontinuation and stopping rates were calculated from GWPCARE6 and the subsequent open-label extension (NCT02544750). The impact of the new National Institute for Health and Care Excellence (NICE) disease severity modifier was also examined.

RESULTS: Compared with placebo, the incremental cost-effectiveness ratio (ICER) per quality-adjusted life year of cannabidiol was £12876 and, following application of the disease severity modifier, £10730. Results were robust to sensitivity and scenario analyses. The most influential scenario was the inclusion of social and educational care resource use, which resulted in a dominant ICER. Parametric sensitivity analysis showed the ICER was most sensitive to the stopping rule assessment rate at 6 months.

CONCLUSIONS: Despite conservative assumptions, cannabidiol is a cost-effective treatment option for TSC-associated seizures compared with placebo.