The cost-utility of sodium oxybate as narcolepsy treatment

Based on class-I studies, sodium oxybate is regarded as a first-line treatment for both EDS and cataplexy. The cost-effectiveness of sodium oxybate is largely unknown, though. In this study, we estimate the cost-effectiveness of sodium oxybate as treatment for patients with narcolepsy as compared to standard treatment, by calculating incremental cost-effectiveness ratios (cost per quality-adjusted life year, QALY) for patients in a Swedish setting.

Calculations were performed using a Markov model with a 10-year time horizon. The study population consisted of adult patients treated for narcolepsy with cataplexy. Healthcare utilization and quality-adjusted life years (QALYs) for each treatment alternative were calculated assuming no treatment effect on survival. Sensitivity analyses were performed for treatment effectiveness and healthcare cost parameters.

The cost per additional quality-adjusted life year was estimated at SEK 563,481. The cost-effectiveness measure was demonstrated to be particularly sensitive to the duration of the relative quality-of-life improvements accruing to patients treated with sodium oxybate.

The estimated cost per additional QALY for the sodium oxybate treatment alternative compared with standard treatment was estimated above the informal Swedish willingness-to-pay threshold (SEK 500,000). The estimated cost per additional QALY obtained here is likely to overestimate the true cost-effectiveness ratio as potentially beneficial effects on productivity of treatment with sodium oxybate were not included (due to lack of data).