Cost-Effectiveness of Cannabidiol Adjunct Therapy versus Usual Care for the Treatment of Seizures in Lennox-Gastaut Syndrome
Cannabidiol (CBD) is a novel therapy for the treatment of Lennox-Gastaut Syndrome (LGS), a rare, treatment-refractory epileptic encephalopathy. Two pivotal trials found CBD 20 mg/kg/day conferred a reduction from baseline in median drop seizure frequency of 44% and 42%, respectively, compared with 22% and 17%, respectively, in the usual care arms. No economic evaluations have been published to date. This analysis assessed the cost effectiveness of CBD adjunct therapy compared with usual care alone in LGS from the US payer perspective. We developed a lifetime horizon Markov decision analytic model. Efficacy, healthcare costs (2020 US$), and health state utilities were ascertained from published clinical trials, retrospective analyses, and time trade-off interviews conducted in the UK, respectively. Fifteen-year-old patients entering the model transitioned to states representing a percentage reduction in drop seizure frequency from baseline, where they remained until reverting back to baseline drop seizure frequency, or death. One-way and probabilistic sensitivity analyses were conducted to evaluate parameter uncertainty, and scenario analyses investigated the impact of various assumptions. Costs and outcomes were discounted at 3%. Compared with usual care alone, CBD yielded 0.7 additional quality-adjusted life-years (QALYs) and $314,900 additional healthcare expenditure, resulting in $451,800 per QALY. Uncertainty in health state utilities were the largest contributor to uncertainty in the results. Results from the 5000-simulation probabilistic sensitivity analysis indicated a 0% chance of CBD being cost effective at a $150,000 per QALY willingness-to-pay threshold, with a 95% credible range for the incremental cost-effectiveness ratio of $325,300–$690,000 per QALY. CBD does not appear to be a cost-effective therapeutic option in LGS patients at a willingness-to-pay threshold of $150,000/QALY.