Mandatory nonmedical switching from originator to biosimilar infliximab in patients with inflammatory arthritis and psoriasis in British Columbia: a cohort study


Mandatory nonmedical switching from originator to biosimilar infliximab in patients with inflammatory arthritis and psoriasis in British Columbia: a cohort study

psoriasisAnat Fisher, Jason D. Kim, Colin R. Dormuth


Background: In 2019, British Columbia’s public drug plan, PharmaCare, was the first in Canada to implement a nonmedical switching policy from originator infliximab to its biosimilar, for patients with inflammatory arthritis or psoriasis. We aimed to detect signals of impact on health services utilization during the first year of policy implementation and to provide early data to policy-makers.

Methods: We constructed cohorts of users of originator infliximab: 3 historical cohorts (2016–2018) and 1 policy cohort (2019). We extracted data from BC Ministry of Health databases from 2015 to 2020, as we followed each cohort for 365 days from May 27 of each cohort’s respective year. We excluded patients with gastrointestinal conditions and those not covered by PharmaCare. We examined the cumulative incidence of infliximab prescription refills, switching to other biologic drugs and use of additional health services. A log-likelihood ratio of 1.96 compared with the null hypothesis was used as the threshold for differences between the policy cohort and the historical cohorts.

Results The study included a total of 572 unique patients: 520 in the 2016 historical cohort, 461 in the 2017 historical cohort, 423 in the 2018 historical cohort and 377 in the policy cohort (with some patients included in multiple cohorts; 335 [58.6%] were included in all 4 cohorts). During months 8 and 9 of follow-up, a transient signal was observed in infliximab refills (7.2% decrease in refilling infliximab for the fourth time for the policy cohort, log-likelihood ratio > 1.96). An anticipated increase in visits to specialists was observed from month 4 forward (15.0%, log-likelihood ratio > 1.96). No signal was observed for increased use of other health services (log-likelihood ratio < 1.96).

Interpretation: Early monitoring did not detect signals of negative impacts on health services use during the first year of the policy. Detailed, longer-term cohort studies and hypothesis-testing methods could provide additional assurance about the safety of the policy.

Worldwide spending on biologic medications is high and increasing, and governments face the challenge of providing these medications and other treatments within limited budgets. The use of biosimilar medications has the potential to reduce costs while providing clinical benefits similar to those of the originator medications. To encourage switching from originator biologics to biosimilar medications, some governments are implementing voluntary or mandatory nonmedical switching policies. Despite evidence that switching is not associated with negative health impacts, many patients and physicians are concerned that switching will reduce the effectiveness of treatment or cause adverse effects (or both). Unintended negative effects may be a particular concern when switching is mandatory, regardless of a patient’s clinical presentation or medical history. Close monitoring of the impacts of mandatory switching policies is needed to provide early data on the safety of these policies.

On May 27, 2019, British Columbia was the first Canadian province to implement a mandatory nonmedical switch policy from an originator to a biosimilar medication. Phase 1 of the BC Biosimilars Initiative targeted patients with rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis or plaque psoriasis who were treated with the originator infliximab and reimbursed by the provincial drug plan, PharmaCare. In BC, the costs for infliximab are covered under a PharmaCare Special Authority process. Since May 27, 2019, only the biosimilar infliximab has been approved in response to new or renewal Special Authority requests for patients with inflammatory arthritis or psoriasis. Patients with existing approval were required to switch to the biosimilar infliximab during a 6-month transition period, and after Nov. 25, 2019, PharmaCare no longer covered the costs of originator infliximab.

The launch of the Biosimilars Initiative was followed by real-time monitoring of its impacts. Some impacts were expected, such as an increase in visits to specialists during the 6-month transition period or immediately thereafter because of patient–physician consultations needed to monitor a switch to a biosimilar. Also, a shift in health services utilization was expected beginning Mar. 17, 2020, when the provincial government announced a state of emergency due to the COVID-19 pandemic. Specifically, we anticipated a decrease in visits to physicians and hospitals, as well as a change in the refilling of prescriptions due to stockpiling (panic buying) or manufacturing disruption.

Our objective was to monitor signals of intended and unintended impacts of the Biosimilars Initiative on drug and health services utilization during the first year of implementation.

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