Rapid monitoring of health services use following a policy to switch patients from originator to biosimilar etanercept-a cohort study in British Columbia.

Background: Drug coverage policies that incentivize switching patients from originator to biosimilar products may result in significant health care savings. Our study aimed to detect early impacts on health services utilization following a mandated switch from originator to biosimilar etanercept in British Columbia (BC), Canada.

Methods: We conducted a prospective, population-based cohort study using linked administrative health data from BC (2010-2020). The policy cohort consisted of patients with inflammatory arthritis who used originator etanercept in 2019, prior to BC's Biosimilars Initiative switching policy. Three historical cohorts included patients with inflammatory arthritis who used originator etanercept in the years 2016, 2017, and 2018. We compared the daily cumulative incidences of drug refills and outpatient and inpatient services between the policy and historical cohorts. A likelihood ratio sustained (≥ 31 days) at 7.1 or higher compared with the null hypothesis was chosen a priori as a threshold for a potential impact of the policy.

Results: Each cohort contained between 1694 and 1963 patients. We detected several potential impacts: 1) a transient increase in etanercept refills between months three and eight (cumulative incidence difference of + 3.0%); 2) an anticipated increase in visits to physicians of any specialty between months three and eight (+ 2.6%); and 3) an anticipated increase in visits to a rheumatologist from the end of month three onwards (+ 12.8%). The policy had no impact on incidences of switching to a different biologic antirheumatic drug, visits to emergency departments, or admissions to hospitals.

Conclusions: Only transient and/or anticipated increases in drug refills and physician visits were observed during the study period. Additional research on clinical outcomes is recommended to strengthen the evidence that no long-term unintended negative health impacts are associated with BC's Biosimilars Initiative [switching policy].