Real-World Effectiveness of Delayed-Release Dimethyl Fumarate in Patients with Relapsing-Remitting Multiple Sclerosis: Interim Results from the Effect Study

Background: Delayed-release dimethyl fumarate (DMF) has demonstrated a favorable benefit–risk profile in patients with relapsing-remitting multiple sclerosis (RRMS) in well-controlled, clinical trials (DEFINE, NCT00420212 and CONFIRM, NCT00451451), including those who were treatment naïve or early switch patients.

Objectives : The observational EFFECT study (NCT02776072) was undertaken to evaluate the effectiveness of DMF in patients with RRMS in a clinical practice setting, as measured by the proportion of patients who experienced a relapse within the 12 months after initiation of treatment, as well as in a subset of newly diagnosed patients.   

Methods: In this international, multicenter, retrospective observational study, medical records were reviewed at a single time point for patients diagnosed with RRMS who were treated in routine clinical practice. To be included in this analysis, patients had to have initiated DMF treatment after December 2010 and had ≥12 months of follow-up data available following DMF initiation. Enrolled patients could either be treatment naïve or have received only IFN or GA as prior therapy. The proportion of patients relapsed was estimated using the Kaplan-Meier (KM) product limit method, based on time-to-first-relapse survival distribution. Unadjusted ARR was computed as total number of relapses divided by the total patient-years of exposure; confidence intervals were calculated from an unadjusted Poisson regression model using the generalized estimating equation.

Results: As of December 15, 2016, 804 patients (treatment naïve or had received only IFN or GA) were included in the overall analysis. At 12 months following initiation, the KM estimate of the proportion of patients who experienced a relapse was 11.7%. ARR was significantly lower at 12 months after initiation of DMF treatment compared with the 12 months prior (0.15 [95% CI: 0.12, 0.18] vs 0.49 [0.45, 0.54]; rate ratio (95% CI) 0.30 [0.24, 0.37]; P<0.001).In the first 12 months of DMF treatment, 114 (14%) patients discontinued DMF; top reasons (≥1 reason could be listed) included tolerability (9%), efficacy (2%), safety (2%). and patient preference (2%).  

Conclusions: Treatment with DMF was associated with a lower relapse rate in the 12 months after, compared to the 12 months prior to, initiating DMF treatment. This interim analysis suggests that DMF is effective in patients who were treatment naïve or had received only IFN or GA in the clinical practice setting.