An observational, retrospective, UK and Ireland audit of patient adherence to subcutaneous interferon beta-1a injections using the RebiSmart® injection device

BACKGROUND Poor adherence to disease-modifying drugs is associated with an increased risk of relapse in patients with multiple sclerosis. However, adherence is difficult to assess objectively. RebiSmart(®) (Merck Serono SA, Geneva, Switzerland), a device for subcutaneous (sc) injection of interferon (IFN) β-1a, features an electronic injection log that can assist in objective monitoring of adherence. OBJECTIVE To assess adherence to sc IFN β-1a injections using data from RebiSmart(®). METHODS This was a single-group, observational, retrospective audit. Adherence data were collected from patients with relapsing multiple sclerosis in the United Kingdom and Ireland who had been prescribed sc IFN β-1a and had been using RebiSmart(®) for a minimum of 24 months. RESULTS In total, 225 patients were included in the full analysis set; 72% were in the United Kingdom, and 28% were in Ireland. Overall, the mean age was 44.1 years, and 73% were women. Patients received sc IFN β-1a 44 µg (68%) or 22 µg (32%) three times per week. Mean adherence over the course of 24 months was 95.0% (median, 99.4%), and similar values were observed across all periods. The proportion of patients with 80% or higher adherence was 92.0% at 12 months and 91.1% at 24 months. CONCLUSION High adherence to sc IFN β-1a was observed across all patient groups using RebiSmart(®), according to 2-year treatment adherence data. This may be partly attributed to the expert support patients received, supplemented by routine and regular contact from the MySupport patient-support program, as well as the self-motivation of patients who persisted with treatment for 2 or more years.