Estimation of the effect of dalfampridine-ER on health utility by mapping the MSWS-12 to the EQ-5D in multiple sclerosis patients

Abstract

Background: Trials have not assessed the effect of dalfampridine-extended release (dalfampridine-ER) on health utility. We sought to evaluate the effect of dalfampridine-ER tablets (prolonged-release fampridine in Europe) on health utility in patients with multiple sclerosis (MS) by mapping subjects’ individual item scores from the 12-Item Multiple Sclerosis Walking Scale (MSWS-12) onto the Euroqol 5-Dimension (EQ-5D) health utility index. Methods: Data from study MS-F203, a randomized trial of dalfampridine-ER tablets, 10 mg twice daily, in patients with MS, were used to calculate the health utility scores with two MSWS-12 to EQ-5D mapping equations (one derived in a North American [NA] registry, the other a United Kingdom [UK] registry). MS-F203 participants were categorized as dalfampridine-ER 20%-responders (achieving ≥20% improvement on the Timed 25-Foot Walk), dalfampridine-ER 20%-nonresponders ( 0.05 at weeks 16 and 18). Dalfampridine-ER 20%-nonresponders did not show improvement vs. placebo at any visit (p > 0.05 for all). When using the UK-derived equation, improvement was seen in dalfampridine-ER 20%-responders vs. placebo at weeks 2, 6, 10, and 14 (ESs = 0.49, 0.55, 0.59, and 0.99; p < 0.03 for all), but not when dalfampridine-ER was discontinued (weeks 16 and 18; p > 0.05 for both). Dalfampridine-ER 20%-nonresponders showed no improvement at any visit (p > 0.05 for all). Conclusion: Regardless of the equation used, dalfampridine-ER response was associated with an improvement in health utility.