BACKGROUND AND AIMS: In 2019, British Columbia (BC) became the first jurisdiction in North America to introduce a mandatory non-medical switching (NMS) policy requiring patients with Crohn's disease (CD) and ulcerative colitis (UC) to be switched from originator biologics to biosimilar equivalents. This study examines the influence of the BC Biosimilars Initiative NMS policy on the longer-term infliximab and adalimumab biosimilar utilization and patterns of continuation/discontinuation of biosimilars. METHODS: We used health administrative data from BC to study drug utilization trends between 2015 and 2022. We used an interrupted time series design with segmented regression analysis to evaluate the impact of the Biosimilars Initiative on the utilization of biosimilars for infliximab and adalimumab and marginal Cox regression models to explore predictors of discontinuation of biosimilars post NMS. RESULTS: The Biosimilars Initiative was associated with an increase in the proportion of biosimilars within the anti-TNF market of 29.3% (95% CI: 28.6%, 29.9%) in Phase 1 (infliximab) and 49.5% (95% CI: 48.4%, 50.7%) in the adalimumab phase; thereafter, biosimilar use increased by 1.5% per year (95% CI: 0.3%, 2.7%). After the NMS, by the end of 2022, 13.5% (n = 4648) had switched from a biosimilar to an originator or a biologic in a different class. Female patients and biologic-naive patients starting on a biosimilar were more likely to switch from a biosimilar to another drug. CONCLUSIONS: Our results suggest that the Biosimilars Initiative NMS in BC was successful in switching patients to biosimilars and that most patients remained on biosimilar versions.
Harrison et al. (Tue,) studied this question.