Utilization and Switch Patterns with Dimethyl Fumarate in a Publicly-Funded Drug Plan: The First Eight Months

Background: Dimethyl fumarate was the first oral disease-modifying therapy (DMT) approved for formulary coverage under the publicly-funded drug plan in Saskatchewan, Canada for first-line treatment of relapsing-remitting multiple sclerosis (MS). Tracking requests for drug coverage in a publicly-funded system provides unique information related to utilization patterns and insight into rationale for treatment decisions concerning drug initiations and switches.   

Objectives: Describe the utilization patterns (initiations and switches) of dimethyl fumarate, and explore the reasons for switches provided by the prescribing physician for persons covered by the publicly-funded drug plan in Saskatchewan. 

Methods: Utilization data came from the Saskatchewan MS Drugs Research Program starting from the formulary approval date for dimethyl fumarate (1 May 2014).  All publicly-funded DMT requests are processed through the Saskatchewan MS Drug Program, ensuring a high rate of capture.  Preliminary descriptive statistics are reported. 

Results: As of 6 January 2015, 857 persons were receiving coverage for an approved DMT through the Saskatchewan MS Drugs Program, including 239 (27.9% percent) for dimethyl fumarate. From May to December 2014, 285 applications were approved for dimethyl fumarate: 68 new starts and 217 switching from another DMT. Among the 217 applications switching to dimethyl fumarate, 45.6% and 76.0% switched within the first three and six months, respectively from the time the drug received formulary approval. Preliminary analysis suggests the main reasons for switching to dimethyl fumarate were injection fatigue, relapses/progression, injection-site reactions, and intolerable side effects.  Switching from dimethyl fumarate to other DMTs was first observed six months after formulary approval (n=21). Further analyses and updates of switches will be reported in the final poster. 

Conclusions: Utilization of dimethyl fumarate in a publicly-funded system began immediately after formulary approval.  Switches in the first six months were from other DMTs to dimethyl fumarate; however, switching from dimethyl fumarate to other DMTs has subsequently increased.  Further examination of reasons for switching, and other utilization patterns including adherence, may help identify previously unrecognized adverse effects, as well as guide MS management and future health policy.