Adherence and discontinuation rates in patients on Tecfidera™ (dimethyl fumarate): Long-term Canadian experience from the Biogen ONE™ support program

•Dimethyl fumarate (DMF) is a disease-modifying therapy for multiple sclerosis (MS).•90.4% of patients (N = 6848) were adherent to DMF in this Canadian support program.•Persistence on DMF treatment was 57.0% at 24 months.•Mean decrease in absolute lymphocyte count was 29.2% in the first year of treatment.•As the program continued (2013–2021), DMF was initiated earlier in the course of MS.