Retigabine as add-on treatment of refractory epilepsy--a cost-utility study in a Swedish setting

To calculate comparative incremental cost-effectiveness ratios (cost per quality-adjusted life year, QALY) and net marginal benefits for retigabine as add-on treatment for patients with uncontrolled focal seizures as compared to add-on lacosamide treatment and no add-on treatment, respectively.

Calculations were performed using a validated decision-tree model. The study population consisted of adult patients with focal-onset epilepsy in published randomized placebo-controlled add-on trials of retigabine or lacosamide. Healthcare utilization and QALY for each treatment alternative were calculated. Probabilistic sensitivity analysis was performed using the specification of this model as a basis for Monte Carlo simulations. 2009 prices were used for all costs.

Results were reported for a 2-year follow-up period. Retigabine add-on treatment was both more effective and less costly than lacosamide add-on treatment, and the cost per additional QALY for the retigabine no add-on (standard) therapy comparison was estimated at 2009€ 15,753. Using a willingness-to-pay threshold for a QALY of € 50,000, the net marginal values were estimated at 2009€ 605,874 for retigabine vs lacosamide and 2009€ 2,114,203 for retigabine vs no add-on, per 1,000 patients. The probabilistic analyses showed that the likelihood that retigabine treatment is cost-effective is at least 70%.

The estimated cost per additional QALY, for the retigabine vs no add-on treatment comparison, is well within the range of newly published estimates of willingness to pay for an additional QALY. Thus, add-on retigabine treatment for people with focal-onset epilepsy with no/limited response to standard antiepileptic treatment appears to be cost-effective.