Adherence to disease-modifying therapies in spanish patients with relapsing multiple sclerosis: two-year interim results of the global adherence project.

The post-marketing international Global Adherence Project investigated adherence to disease-modifying therapy for relapsing-remitting multiple sclerosis. We report adherence data from the first 2 years in the Spanish subset of patients (n = 254 at baseline). The overall adherence rate was 85.4%. Patients taking intramuscular (IM) interferon-β (IFNβ)-1a were significantly more adherent (96.4%) compared with patients taking subcutaneous (SC) IFNβ-1a 22 µg (79.1%; p = 0.0064), SC IFNβ-1a 44 µg (79.6%; p = 0.0064) and glatiramer acetate (82.7%; p = 0.0184). At year 1 (n = 142), the overall adherence rate was 86.6%. Patients on IM IFNβ-1a were significantly more adherent than patients on SC IFNβ-1a 22 µg (93.9 vs. 66.7%; p = 0.0251). At year 2 (n = 131), the overall adherence rate was 82% (87.5% for IM IFNβ-1a, 80.0% for SC IFNβ-1a 22 µg, 77.8% for SC IFNβ-1a 44 µg, 85.2% for IFNβ-1b, and 80.0% for glatiramer acetate). In conclusion, adherence remained high among all disease-modifying therapies over the first 2 years of the study and was significantly higher for IM IFNβ-1a, at visit 1, compared with SC IFNβ-1a.