Impact of drug policy on regional trends in ezetimibe use.
BACKGROUND
Ezetimibe use has steadily increased in Canada during the past decade even in the absence of evidence demonstrating a beneficial effect on clinical outcomes. Among the 4 most populated provinces in Canada, there is a gradient in the restrictiveness of ezetimibe in public-funded formularies (most to least strict: British Columbia, Alberta, Quebec, and Ontario). The effect of formulary policy on the use of ezetimibe over time is unknown.


METHODS AND RESULTS
We conducted a population-level cohort study using Intercontinental Marketing Services Health Canada's data from June 2003 to December 2012 to examine ezetimibe use in these 4 provinces to better understand the association between use and formulary restrictiveness. We found regional variations in the patterns of ezetimibe use. From June 2003 to December 2012, British Columbia (most restrictive) had the lowest monthly increasing rate from $261 to $21 926 ($190/100 000 population/mo), whereas Ontario (least restrictive) had the most rapid monthly increase from $223 to $74 030 ($ 647/100 000 population/mo), and Quebec from $130 to $59 690 ($522/100 000 population/mo) and Alberta from $356 to $ 37 604 ($327/100 000 population/mo) were intermediate (P<0.001).


CONCLUSIONS
Ezetimibe use remains common, increasing during the past decade. Use steadily increased in provinces with the most lenient formularies. In contrast, use was lower, plateauing since 2008 in British Columbia and Alberta, which have more restrictive formularies. The gradient in ezetimibe use was related to variability in restrictiveness of the provincial formularies, illustrating the potential of a policy response gradient that may be used to more effectively manage medication use.