The prescription patterns and adherence of disease-modifying drugs for Multiple Sclerosis in Saskatchewan 1997-2013

Background: The disease modifying drugs (DMDs) for Multiple Sclerosis were approved as a benefit by the Provincial Drug Plan under Exception Drug Status, Department of Health, Saskatchewan, in November 1997. It is estimated that thirty to forty percent discontinue treatment within two years. The objective is to compare the prescription patterns and adherence of four approved DMD's. Methods: A prospective database and cohort analysis of all applications eligible for drug prescriptions was maintained 16 years. Descriptive analysis was performed after November 15th 2013 using SPSS v21. Results: There were 1565 eligible prescriptions, including Avonex 168 (10.7%), Betaseron 355 (22.7%), Copaxone 723 (46.2%), and Rebif 318 (20.3%). 1409 (90%) started a dmg. Currently 546 (34.9%) remain on the initial prescription including Avonex 52 (30.9%), Betaseron 83 (23.4%), Copaxone 293 (40.5%), and Rebif 118 (37.1%), the latter two drugs showing a higher adherence rate. 863 discontinued and 156 never started. 565 persons were prescribed 2-5 drugs. 796 (50.9%) continue treatment including 250 persons who switched. Conclusions: The adherence on DMD treatments is low, even after changing treatments. Further study is warranted to understand the factors which impact drug utilization in Multiple Sclerosis.