The Global Adherence Project (GAP): a multicenter observational study on adherence to disease-modifying therapies in patients with relapsing-remitting multiple sclerosis

Background: Most disease-modifying therapies (DMTs) for multiple sclerosis (MS) are self-injectable medications that must be taken on an ongoing basis to reduce disease activity. Thus, adherence to therapy becomes an important challenge that must be addressed to maximize benefits of therapy. This study evaluated rates of adherence to prescribed treatment and explored factors affecting adherence amongst patients with relapsing-remitting MS. Methods: This was an observational, multicenter, multinational, phase 4 study. Patients and physicians received paper questionnaires regarding adherence to DMTs approved at the time of the study, including intramuscular interferon beta-1a (IFN beta-1a), subcutaneous IFN beta-1a, IFN beta-1b, and glatiramer acetate. Quality of life and cognition data also were collected. Multivariate analysis was conducted to identify factors associated with adherence to long-term DMTs. Results: Two thousand six hundred and forty-eight patients were studied, revealing an average treatment duration of 31 months. Seventy-five percent of patients (n = 1923) were adherent to therapy. The most common reasons for non-adherence were forgetting to administer the injection (50.2%) and other injection-related reasons (32.0%). Adherent patients reported better quality of life (P < 0.05) and fewer neuropsychological issues (P < 0.001) than non-adherent patients. Adherent patients had significantly shorter duration of disease (P < 0.001) and shorter duration of therapy (P = 0.005) than non-adherent patients. Women were more likely than men to adhere to treatment. Conclusion: Identifying factors that affect adherence to prescribed treatments is the first step in improving adherence of patients with MS to therapy, thereby helping maximize the benefits of long-term DMTs.