Persistence and adherence to the new oral disease-modifying therapies for multiple sclerosis: A population-based study

Objective: To examine persistence and adherence to the oral disease-modifying therapies (DMTs) for multiple sclerosis (MS). Methods: Population-based health administrative databases in British Columbia, Canada were accessed to identify all individuals filling an oral DMT prescription for MS (fingolimod, dimethyl fumarate, teriflunomide) between January 2011 and December 2015. Predictors of persistence and adherence at 6 and 12 months were assessed using logistic regression, with estimates expressed as adjusted odds ratios (aORs), and 95% confidence intervals (CIs). Results: Of 858 individuals with >= 6 months of follow-up, the mean age at first prescription was 43.0 (SD:10.3) years; 74.2% were women. By 6 months 11.0% (94/858) had discontinued their initial oral DMT; by 12 months the proportion was 19.6% (113/577). Over 6 and 12 months, among those persisting with their oral DMT, 82.5% (630/764) and 81.7% (379/464) exhibited optimal adherence (proportion of days covered >= 80%). Age, sex, calendar year and comorbidity were not associated with persistence or adherence. Individuals with higher neighbourhood-level socioeconomic status had higher odds of discontinuation within 6 months (aOR = 2.2; 95%CI:1.3-3.7). Those who had previously used another DMT had higher odds of optimal adherence (6 months aOR = 2.4;95%CI:1.6-3.6, and 12 months aOR = 2.4; 95%CI:1.5-3.9). Conclusion: Approximately 1 in 10 individuals discontinued their first oral DMT within 6 months, and 1 in 5 did so within one year. However, among those who did continue drug, a high proportion (>80%) exhibited optimal adherence. Predictors of persistence or adherence with immediate practical application were lacking; this highlights the challenges in optimizing drug therapy.