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®) were significantly more adherent (94.6%) compared with patients taking subcutaneous (s.c.) IFNB-1a 22.g (Rebif®22) (79.1%; p=0.0064), s.c. IFNB-1a 44.g (Rebif®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®22 (93.9% versus 66.7%; p=0.0251). At V2 (n=131), the overall adherence rate was 82.4% (Avonex®, 87.5%; Rebif®22, 80%; Rebif®44, 77.8%; Betaferon®, 85.2%, and Copaxone®, 80%) without significant differences.

Conclusions: Adherence remained high over the first 2 years of the study. It was highest with Avonex®, being significant on first assessment, after 40.5 months of therapy, on average compared with other DMTs and at year 1 compared with Rebif®22.