Objective: The course of multiple sclerosis may be slowed by use of the disease modifying drugs (DMDs): subcutaneous or intramuscular interferon beta-1a, interferon beta-1b, glatiramer acetate, and natalizumab. We set out to compare utilization of these drugs in the Canadian provinces from 2002-2007.

Methods: Using a retrospective cohort analysis, we reviewed population data from International Medical Statistics (IMS) Health between November 2001 and October 2007.

Results: The total annual number of DMD prescriptions increased from 3.9, in 2002, to 5.1, in 2007, per 1,000 Canadians. The total annual cost of prescriptions rose from $187 million to $287 million. Of the four provinces responsible for the majority of prescriptions--Alberta, BC, Ontario, and Quebec--Quebec had the highest average annual prescription rate (7 per 1,000 population) and BC had the lowest rate (3.3 per 1,000 population). Subcutaneous interferon beta-1a was the most commonly used drug whereas glatiramer acetate showed the greatest growth in use from 2002 to 2007.

Conclusions: Disease modifying drugs prescription rates and costs increased by more than 30% between 2002 and 2007. There was wide variation in DMD prescription rates and relative drug preferences across the provinces.