Comparative effectiveness of dimethyl fumarate as the initial and secondary treatment for MS

Background: Population-based real-world evidence studies of the effectiveness and tolerability of dimethyl fumarate in relation to common treatment alternatives are still limited. Objective: To evaluate the clinical effectiveness and tolerability of dimethyl fumarate (DMF) as the initial and secondary treatment for relapsing-remitting multiple sclerosis (RRMS) patients compared with common treatment alternatives in Sweden. Methods: We conducted a nationwide retrospective observational cohort study of all RRMS patients identified through the Swedish MS registry initiating DMF (n = 641) or interferons/glatiramer acetate (IFN/GA; n = 555) as the initial therapy, or DMF (n = 703) or fingolimod (FGL; n = 194) after switch from IFN/GA between 1 January 2014 and 31 December 2016. Results: The discontinuation rate was lower with DMF as the initial treatment than IFN/GA (adjusted hazard rate (HR): 0.46, 95% confidence interval (CI): 0.37-0.58, p < 0.001), but higher than FGL as the secondary treatment (HR: 1.51, CI: 1.08-2.09, p < 0.05). Annualized relapse rate (ARR) was lower with DMF compared to IFN/GA (0.04, CI: 0.03-0.06 vs 0.10, CI: 0.07-0.13; p < 0.05), but not FGL (0.03, CI: 0.02-0.05 vs 0.02, CI: 0.01-0.04; p = 0.41). Finally, time to first relapse (TTFR) was longer with DMF as the initial, but not secondary, therapy (p < 0.05 and p = 0.20, respectively). Conclusion: Our findings indicate that DMF performs better than IFN/GA as the initial treatment for RRMS. Compared to FGL, DMF displayed a lower tolerability, but largely similar effectiveness outcomes.