Uptake and Spending on Biosimilar Infliximab and Etanercept After New Start and Switching Policies in Canada: An Interrupted Time Series Analysis.

Objective: Uptake of biosimilars has been suboptimal in North America. This study was undertaken to quantify the impact of various policy interventions (namely, new start and switching policies) on uptake and spending on biosimilar infliximab and etanercept in British Columbia (BC), Canada.

Methods: We used administrative claims data to identify BC residents ≥18 years of age with rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, and/or plaque psoriasis who qualified for public drug coverage from January 2013 to November 2020. Using interrupted time series analysis, we studied the change in proportion spent on and prescriptions dispensed of biosimilar infliximab and etanercept out of the total amount per agent after new start and biosimilar switching policies were implemented.

Results: Our study included 208,984 individuals living with rheumatoid arthritis, ankylosing spondylitis, plaque psoriasis, and/or psoriatic arthritis, corresponding to 5,884 patients taking infliximab and etanercept. After the new start policy, we detected a small gradual increase in the proportion of dispensed biosimilar etanercept prescriptions of 0.65% per month (95% confidence interval [95% CI] 0.44, 0.85). The trend related to the proportion of total spending on biosimilar etanercept also increased (0.51% [95% CI 0.28, 0.73]). After the switching policy, there was a sustained increase in the proportion of dispensed biosimilar etanercept and infliximab prescriptions of 76.98% (95% CI 75.56, 78.41) and 58.43% (95% CI 52.11, 64.75), respectively. Similarly, there was a persistent increase in monthly spending on biosimilar etanercept and infliximab of 78.22% (95% CI 76.65, 79.79) and 71.23% (95% CI 66.82, 75.65), respectively.

Conclusion: We found that mandatory switching policies were much more effective than new starting policies for increasing the use of biosimilar medications.