Effects of Dalfampridine Extended Release on Motor Function in Persons with Multiple Sclerosis after 18 Months

Background: Motor improvements have been reported in persons with multiple sclerosis (pwMS) on dalfampridine extended release (D-ER). However, little evidence exists on the longer term benefits of taking D-ER across a range of motor functions.

Objectives: Assess motor function in pwMS on D-ER for 18 months.

Methods: Prior to initiating D-ER, 52 participants enrolled in this prospective observational study of pwMS prescribed 10mg D-ER per usual care; 33 were observed for 18 months. The following outcomes were assessed at baseline (pre D-ER) and follow up (18 months): Timed 25 Foot Walk (T25FTW), 6 Minute Walk (6MW), Six Spot Step Test (SSST), 12-Item Multiple Sclerosis Walking Scale (MSWS-12), 9-Hole Peg Test (9HPT), and Box and Block Test (BBT). Changes from baseline to 18 months were assessed separately for 1) those remaining on D-ER at 18 months (n=18) and 2) those who discontinued D-ER (n=15) prior to 18 months, using Wilcoxon signed ranks test.

Results: Among those who remained on D-ER, the following significant improvements (median change, p-value) were seen at 18 months compared to baseline (pre D-ER): SSST dominant (dom) (-3.0, 0.006), SSST combined (-2.3, 0.056), MSWS-12 (-11.5, 0.050), BBT dom (2.8, 0.023) and BBT non-dom (3.8, 0.006). Among those who discontinued D-ER (n=15), only SSST dom (-2.0, 0.020) was improved. No significant improvements were seen in the following among those who remained on D-ER: T25FTW (-0.3, 0.196), 6MW (3.0, 0.776), SSST non-dom (-0.9, 0.278), 9HPT dom (-1.1, 0.122), and 9HPT non-dom (-1.3, 0.064).  Among those who discontinued D-ER, no improvements were found for: T25FTW (-0.1, 0.820), 6MW (-6.0, 0.096), SSST non-dom (-0.8, 0.776), SSST combined (-2.0, 0.191), MSWS-12 (-2.1, 0.670), 9HPT dom (0.7, 0.443), 9HPT non-dom (-3.2, 0.460), BBT dom (-0.8, 0.953), and BBT non-dom (-0.5, 0.239).  

Conclusions: Current findings suggest improvements in gross motor function, dynamic gait, and self-perceived walking for pwMS on D-ER sustained after 18 months are possible. Additional research including an untreated comparison group is needed to better understand the longer term effects of D-ER on motor function in pwMS.