An evaluation of adherence in patients with multiple sclerosis newly initiating treatment with a self-injectable or an oral disease-modifying drug

OBJECTIVE As the multiple sclerosis (MS) disease-modifying drug (DMD) treatment options have expanded to include oral therapies, it is important to understand whether route of administration is associated with DMD adherence. The objective of this study was to compare adherence to DMDs in patients with MS newly initiating treatment with a self-injectable versus an oral DMD. METHODS This retrospective database study used IMS Health Real World Data Adjudicated Claims - US data between July 1, 2010 and June 30, 2014. Adherence was measured by medication possession ratio (MPR), calculated as the total number of treated days divided by the total number of days from the first treated day until the end of 12-month follow-up. A binary measure representing adherence (MPR ≥0.8) versus nonadherence (MPR <0.8) to therapy was used. Logistic regression evaluated the likelihood of adherence to index DMD type (self-injectable vs oral). Covariates included patient baseline characteristics (ie, age, sex, comorbidities) and index DMD type. RESULTS The analysis included 7,207 self-injectable and 1,175 oral DMD-treated patients with MS. In unadjusted analyses, the proportion of patients adherent to therapy (MPR ≥0.8) did not differ significantly between the self-injectable (54.1%) and the oral DMD cohorts (53.0%; P=0.5075). After controlling for covariates, index DMD type was not a significant predictor of adherence (odds ratio [OR] 1.062; 95% confidence interval [CI]: 0.937-1.202; P=0.3473). Higher likelihood of adherence was associated with male sex (OR 1.20; 95% CI: 1.085-1.335; P=0.0005) and age groups older than 18-34 years (ORs 1.220-1.331; P<0.01). Depression was associated with a lower likelihood of adherence (OR 0.618; 95% CI: 0.511-0.747; P<0.0001). CONCLUSION Male sex and age older than 18-34 years were significantly associated with a higher likelihood of adherence, while depression was associated with a lower likelihood of adherence. Index DMD type, stratified by the route of administration (self-injectable vs oral DMD), was not a significant predictor of DMD adherence.