Compliance to fingolimod and other disease modifying treatments in multiple sclerosis patients, a retrospective cohort study

Background: Adherence to disease-modifying therapies (DMTs) results in the reduction of the number and severity of relapses and delays the progression of multiple sclerosis (MS). Patients with lower adherence rates experience more inpatient visits and higher MS-related medical costs. Fingolimod, the first oral DMT approved by the US Food and Drug Administration, may improve the access and compliance to MS treatment when compared to injectable DMTs. Methods: This retrospective cohort study used pharmacy claims from Medco Health Solutions, Inc., of patients who initiated DMTs between October 2010 and February 2011. Initiation was defined as no prescription fills for the same DMT in the prior 12 months. Patients without a DMT prescription fill 12 months before the index date were considered naive users. Compliance was measured via proportion of days covered (PDC) and medication possession ratio (MPR) for 12 months post-index. Discontinuation was defined as a >= 60-day gap of index DMT supply. Cox proportional hazard models compared time to discontinuation between cohorts. Results: Of 1,891 MS patients (mean age: 45.7; female: 76.4%), 13.1% initiated fingolimod, 10.7% interferon beta-1b, 20.0% intramuscular interferon beta-1a, 18.8% subcutaneous interferon beta-1a, and 37.4% glatiramer acetate. Patients initiating fingolimod had highest average PDC and MPR in both experienced (fingolimod: mean PDC=0.83, 73.7% with PDC >= 0.8; mean MPR=0.92, 90.5% with MPR >= 0.8) and naive DMT users (fingolimod: mean PDC=0.80, 66.7% with PDC >= 0.8; mean MPR=0.90, 87.4% with MPR >= 0.8). The proportion of patients discontinuing index DMT within 12 months was significantly lower for the fingolimod cohort (naive: 31.3%; experienced: 25.7%). Adjusted results found that patients receiving self-injected DMTs discontinued significantly sooner than fingolimod users. This association was generally stronger in experienced DMT users. Conclusions: Fingolimod initiators were more compliant, less likely to discontinue treatment, and discontinued later than patients who initiated self-injected DMT.