Department of Anesthesiology, Pharmacology and Therapeutics (Fisher, Kim, Dormuth), University of British Columbia, Vancouver, BC
Department of Anesthesiology, Pharmacology and Therapeutics (Fisher, Kim, Dormuth), University of British Columbia, Vancouver, BC.
CMAJ Open. 2022 Feb 15;10(1):E109-E118. doi: 10.9778/cmajo.20200319. Print 2022 Jan-Mar.
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.
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.
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).
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.
2019 年，不列颠哥伦比亚省的公共药品计划 PharmaCare 成为加拿大第一个实施非医学性从原研英夫利昔单抗转换为其生物类似药的政策，适用于患有炎症性关节炎或银屑病的患者。我们旨在检测该政策实施的第一年对卫生服务利用的影响信号，并为政策制定者提供早期数据。
我们构建了原研英夫利昔单抗使用者队列：3 个历史队列（2016-2018 年）和 1 个政策队列（2019 年）。我们从不列颠哥伦比亚省卫生部的数据库中提取了 2015 年至 2020 年的数据，对每个队列从各自年份的 5 月 27 日起进行 365 天的随访。我们排除了有胃肠道疾病和未纳入 PharmaCare 覆盖范围的患者。我们检查了英夫利昔单抗处方续药、转换为其他生物药物和额外卫生服务使用的累积发生率。与零假设相比，对数似然比为 1.96 被用作政策队列与历史队列之间差异的阈值。
该研究共纳入了 572 名患者：2016 年历史队列 520 名，2017 年历史队列 461 名，2018 年历史队列 423 名，政策队列 377 名（部分患者纳入多个队列；335 名[58.6%]纳入了所有 4 个队列）。在随访的第 8 和第 9 个月，观察到英夫利昔单抗续药的短暂信号（政策队列第四次续药的英夫利昔单抗减少 7.2%，对数似然比>1.96）。从第 4 个月开始，预计会增加专科医生就诊（15.0%，对数似然比>1.96）。未观察到其他卫生服务使用增加的信号（对数似然比<1.96）。
早期监测未发现该政策实施的第一年对卫生服务使用产生负面影响的信号。详细的、长期的队列研究和假设检验方法可以为该政策的安全性提供额外的保证。
