Global adherence project to disease-modifying therapies in patients with relapsing multiple sclerosis: 2-year interim results

Background: In this article we report adherence data from the first 2 years in a subset of patients from the Global Adherence Project (GAP; n=2,648) in Spain. Methods: A questionnaire assessing adherence to Disease-modifying therapies (DMTs), was distributed annually to patients and their treating neurologists. Non-adherence was defined as missing a DMT injection or changing a dose in the four weeks prior to completing the survey. Patients signed informed consent and Ethics Committees approved annual follow-ups, visit 1 (V1) and visit 2 (V2) in 15 out of 18 centres in Spain. Results: A total of 254 patients were enrolled in Spain. Patients had a mean age of 37.9 years and 70.4% were female, and had been on their treatment for a median time of 28 months, and the overall adherence rate was 85.4%. Patients taking intramuscular interferon beta (IFNB)-1a (Avonex (R)) were significantly more adherent (94.6%) compared with patients taking subcutaneous (s.c.) IFNB-1a 22 mu g (Rebif (R) 22) (79.1%; p = 0.0064), s.c. IFNB-1a 44 mu g (Rebif (R) 44) (79.6%; p = 0.0064) and glatiramer acetate (GA) (82.7%; p = 0.0184). At V1 (n = 142), the overall adherence rate was 86.6% and patients on Avonex were significantly more adherent than patients on Rebif (R) 22 (93.9% versus 66.7%; p = 0.0251). At V2 (n =131), the overall adherence rate was 82.4% (Avonex (R), 87.5%; Rebif (R) 22, 80%; Rebif (R) 44, 77.8%; Betaferon (R), 85.2%, and Copaxone (R), 80%) without significant differences. Conclusions: Adherence remained high over the first 2 years of the study. It was highest with Avonex (R), being significant on first assessment, after 40.5 months of therapy, on average compared with other DMTs and at year 1 compared with Rebif (R) 22. (C) 2009 Sociedad Espanola de Neurologia. Published by Elsevier Espana, S.L. All rights reserved.