The EP-score to assess treatment efficacy in RRMS patients : a preliminary study

Aim of the study: The aim of this retrospective study was to preliminarily assess whether the EP-score, a summary score derived from multimodal evoked potentials tests, might be used as a measure of treatment efficacy in multiple sclerosis (MS). Materials and methods: A sample of 56 relapsing remitting MS (RRMS) patients who at diagnosis started treatment with interferon β (INFβ, n = 19), glatiramer acetate (GA, n = 15) or refused any chronic treatment were assessed at baseline (before treatment) and at a median of 1.7 and 3.6 years thereafter. Outcome variables were Expanded Disability Status Scale (EDSS), EP-Score, visual evoked potentials (VEP) and somatosensory evoked potentials (SEP) scores measured as differences between baseline and follow-ups. Statistical differences between groups and follow-ups were assessed using non-parametric analyses. Results: Treatment effects were not significant for EDSS both at the first and at the second follow-up, while a trend toward significance was observed in the EP-score only in the first follow-up (p = 0.07). Post-hoc analysis showed a greater decrease in median VEP-score for the IFNβ group compared to the GA and DF groups at both the first and second follow-ups. Conclusions: We found no evidence that either INFβ or GA significantly improved disability in RRMS patients. Using the EP-score as an outcome measure, we found that it was improved at both follow-ups in the INFβ group mainly due to a decrease in the VEP-score. This finding supports the proposal to include the EP-score as an additional outcome variable in future studies of treatment efficacy in MS.