Treatment Adherence, Persistence, and Compliance at 96 Weeks in MS Patients Using Rebismart® for Injection of Interferon β-1a

Background: Treatment with disease-modifying drugs (DMDs) can reduce relapse frequency and slow disability progression among patients with relapsing multiple sclerosis (RMS). However, adherence to treatment is often inconsistent. RebiSmart® is the first electronic auto-injector for subcutaneous interferon β 1a (IFN) treatment of RMS designed to reduce several barriers to optimal treatment adherence.

Objectives: In a multicenter, single-arm, observational, phase IV study, we evaluated 96-week treatment adherence, compliance, and persistence of RMS patients using RebiSmart® for IFN self-injection.

Methods: A total of 162 adult participants with RMS used RebiSmart® to self-administer IFN 44 μg thrice weekly for a maximum of 96 weeks. The number of administered injections was recorded in the electronic device log. Treatment adherence was calculated as 100 × the number of administered injections, divided by the expected number of injections in 96 weeks; compliance was calculated as 100 × the number of administered injections, divided by the number of injections per actual weeks on study. Exploratory logistic regression analyses were carried out to assess potential predictors of adherence, persistence, and compliance to treatment at week 96.

Results: The mean (SD) adherence rate at week 96 was 69.5% (32.9%).  This modest level of adherence reflected a sizeable discontinuation rate by week 96 (37.1%; 95% confidence interval [CI] 30.0% to 44.8%). However, when patients persisted on therapy, the mean (SD) compliance rate at 96 weeks was 91.4% (12.1%). In logistic regression analyses, none of the factors examined, including baseline patient characteristics, disease history, injection anxiety, injection site reactions, and flu-like symptoms significantly predicted treatment compliance at week 96. Older age, and longer time since last relapse were both significant predictors of adherence and persistence to therapy at 96 weeks. According to participant evaluations, the absence of a visible needle was the most important feature of the RebiSmart® injection system. By week 96, 98% of patients stated they would continue using the injector.

Conclusions: RebiSmart® use is associated with high treatment compliance, as objectively assessed using electronic injection logs. Compliance appears not to be significantly influenced by various patient, disease, or injection experience factors.