Adherence to Subcutaneous IFN β-1a in Multiple Sclerosis: Final Analysis of the Non-Interventional Study READOUTsmart Using the Dosing Log and Readout Function of RebiSmart®

Abstract

Patient adherence is a key determinant of treatment success in multiple sclerosis (MS). The RebiSmart® autoinjector facilitates patient self-injection of subcutaneous interferon β-1a (sc IFN β-1a) and allows quantitative measurement of adherence via its automated dosing log. We evaluated patient adherence and patient-reported cognitive and health-economic outcomes over 2years in patients using RebiSmart®. In this non-interventional, single-arm study, enrolled patients were 12-65years of age, had relapsing-remitting MS or a single demyelinating event, and had been prescribed 44 or 22μg sc IFN β-1a. Quantitative adherence (proportion of scheduled injections administered) and qualitative adherence (proportion of weeks with treatment schedule correctly followed) were monitored over 2 years. Other end points included self-assessed adherence, patient-reported outcomes (fatigue, depression and quality of life), cognitive outcomes and health-economic outcomes. A total of 368 of 392 (93.9%) enrolled patients were analyzed. Mean quantitative adherence was 85.3% overall (months 1-24), 89.6% for months 1-12 and 83.3% for months 13-24. No major impact on quantitative adherence was observed for sex, age (< 37years vs. ≥ 37years), prior medication or participation in the patient support program RebiSTAR®. Mean qualitative adherence was 67.0% overall (months 1-24). Self-assessed adherence was reported as being higher than RebiSmart®-monitored adherence. There was a trend toward more MS-related visits to physicians among patients with high adherence. Patients using RebiSmart® demonstrated high adherence to treatment that was associated with a slight improvement in information processing speed and working memory and an overall tendency for more intensive self-management. Merck Serono GmbH, Germany, an affiliate of Merck KGaA, Darmstadt, Germany.