Adherence and Persistence Among Multiple Sclerosis Patients After One Immunomodulatory Therapy Failure: Retrospective Claims Analysis

Introduction: There are no published data on patient adherence to, and persistence with, disease-modifying therapies (DMT) for multiple sclerosis (MS) after one immunomodulatory failure. The present study compares second-line DMT adherence and persistence among patients with MS. Methods: Patients with MS initiating a second-line treatment with natalizumab, intramuscular interferon beta-1a (i.m.-IFN beta-1a), subcutaneous (s.c.) IFN beta-1a, interferon beta-1b (IFN beta-1b), and glatiramer acetate (GA) from January 1, 2006 to October 4, 2008 were identified from a retrospective claims database associated with a large US health plan. Adherence was measured with medication possession ratio (MPR); adherence indicated MPR >= 0.80. Persistence was measured as time until a minimum 60-day gap in second-line therapy. Adherence and persistence were modeled with logistic and Cox proportional hazard regressions, respectively. Results: The study population comprised 1381 patients. Multivariate analysis showed that the odds of adherence were significantly higher in the natalizumab cohort compared with all other second-line cohorts. The natalizumab cohort was more likely to be persistent compared with the i.m.-IFN beta-1a and IFN beta-1b cohorts. Conclusion: The natalizumab cohort was more adherent compared with the other second-line DMT cohorts, likely due in large part to active physician involvement and monitoring. Adherence to DMT, even after first-line failure, is critical to achieving optimal therapeutic benefit.