Abstracts

Rationale: Despite treatment with antiepileptic drugs (AEDs), 20-40% of patients on AEDs are refractory to therapy and remain uncontrolled. Medical care for uncontrolled patients is particularly costly, incurring an additional $14,500 in average annual healthcare costs compared to non-refractory partial-onset seizure patients. The objective of this model was to compare the cost-effectiveness of eslicarbazepine acetate (ESL) to other branded AEDs indicated solely for the adjunctive treatment of partial-onset seizures in adults. Methods: A decision-analytic Markov model was developed to compare the outcomes (response-months, seizures avoided, and quality-adjusted life years [QALYs]) and costs (in 2013 dollars) from a commercial payer perspective over a 3-year time horizon. The model assumes all patients start out with adjunctive treatment with one of the comparator AEDs (ESL, perampanel, oxcarbazepine XR, ezogabine, lacosamide, levetiracetam XR) or placebo (no adjunctive therapy). Patients with a response have a 50% reduction in seizure frequency and continue to experience this reduction in seizure frequency until they discontinue treatment, at which time they revert to the baseline seizure rate. Effectiveness inputs were obtained from a network meta-analysis of the phase III trials of the active comparators. AED cost was determined using US wholesale acquisition cost and market share data (as of April 1, 2014). For ESL, first-year market share projections were used. Health care costs were obtained from the Medical Expenditure Panel Survey (MEPS), and the Healthcare Cost Utilization Project (HCUP). Mortality was adjusted by a standardized mortality ratio to capture the increased mortality risk among patients with epilepsy. The model includes a probabilistic sensitivity analysis (PSA) in which each model parameter is simultaneously sampled using the mean and standard error over 1,000 simulations to estimate the joint uncertainty. Results: Compared to placebo ESL resulted in an additional 3.7 response months, avoidance of 22.2 seizures, and an additional 0.019 QALYs at an incremental cost of $3,263 per response-month, $544 per seizure avoided, and $645,318 per QALY. Compared to the other active comparators ESL demonstrated low treatment discontinuation and ranked consistently in the top three treatment options in terms of its effectiveness and cost profile. ESL was the second most effective treatment in terms of response months, seizures avoided, and QALYs, showing greater overall effectiveness than lacosamide, perampanel, ezogabine, and oxcarbazepine XR. In the PSA, ESL was the second most cost-effective treatment option at a willingness-to-pay threshold greater than $4,000 per response month and $800 per seizure avoided. Conclusions: Based on these model results, ESL compares favorably to other branded AEDs and may be a cost-effective treatment option for refractory patients with partial-onset seizures.