To Örebro University

Background: Dimethyl fumarate (DMF) is an oral therapy for relapsing-remitting multiple sclerosis (RRMS). DMF is included in the Swedish post-market surveillance study “Immunomodulation and Multiple Sclerosis Epidemiology” (IMSE).

Objective: To assess the effectiveness and safety of DMF with focus on patients treated at least 36 months in the IMSE study.

Methods: Descriptive data of Extended Disability Status Scale (EDSS), Multiple Sclerosis Severity Scale (MSSS), Symbol Digit Modalities Test (SDMT), Multiple Sclerosis Impact Scale (MSIS-29), European Quality of Life - 5 Dimensions Test (EQ-5D), Visual Analog Scale (VAS) and Adverse Events (AEs) is obtained from the nationwide Swedish Neuro Registry (NeuroReg). Effectiveness measures were assessed using the Wilcoxon Signed Rank Test and drug survival using the Kaplan-Meier curve.

Results: 2229 DMF-treated patients were included since March 2014 with a one- and two-year drug survival rate of 73% and 59%. The main reasons for discontinuation were AEs (51%) and lack of effect (29%). 77 AEs were reported to the Swedish Medical Products Agency of which 20 were serious. There were 6 fatal cases of which 4 were confirmed as unrelated to DMF and 2 were still under investigation.865 patients had continuous treatment for at least 36 months. This cohort had a mean age of 42 years and a mean treatment duration of 44 months. The majority had switched from interferon and glatiramer acetate (IFN&GA) (50%) or were treatment naïve (TN) (22%). Significant improvements in mean values at 36 months of treatment compared to baseline were noted for EDSS, MSSS, SDMT, MSIS-29 Psychological and EQ-5D. When TN patients were solely assessed improvements were noted for EDSS, MSSS, SDMT, MSIS-29 Physical and Psychological and EQ-5D. Treatment experienced patients displayed significant improvements only for MSSS and EQ-5D. Patients previously treated with IFN&GA also improved only in MSSS and EQ-5D. TN patients had a mean duration from diagnosis to treatment start of 6 months compared to 83 months for IFN&GA patients and 105 months for the remaining cohort.

Conclusions: DMF demonstrates clinical improvements in patients treated ⩾ 36 months, most pronounced in TN patients. However; the tolerability of DMF was reduced since 41% interrupted treatment during the first 24 months of therapy. Continued follow up is needed to assess the effectiveness and safety of DMF over longer time periods in a real world setting.