Background/Purpose: Infliximab (INF) biosimilar was approved for multiple indications in U.S. in 2016. Although clinical trials have demonstrated that switching from infliximab bio-originator to its biosimilar is safe with no significant loss of efficacy, there are limited real-world data comparing their utilization and adherence patterns. Thus, we evaluated medication adherence among INF biosimilar users and compared them to INF bio-originator users using national administrative data, 2014-2018.

Methods: We established 4 cohorts among patients who had at least one administration or pharmacy claim for INF bio-originator or biosimilar in 2017 Truven Marketscan data, including INF biosimilar naïve users, INF biosimilar prevalent users, INF bio-originator naïve users, and INF bio-originator prevalent users. We evaluate the prior use of INF and other biologics using all available data in 2014-2017 prior to the first INF administration in 2017 (index date).The INF naïve users were defined as no prior use of INF bio-originator or INF biosimilar, whereas prevalent users had any prior use of bio-originator INF but no prior INF biosimilar use. Eligible patients were ≥18 years of age, continuously enrolled with full coverage from 2014 and through follow up. Follow-up started on the index date and ended on the earliest date of death, loss of coverage, or 12/31/2018. For patients who had at least 12 or 18 months of follow-up time, we calculated their proportion of days covered (PDC) at 12 or 18 months. Ongoing analyses are adjusting for important patient characteristics that differ across cohorts.

Results: We identified 96 INF biosimilar naïve users, 223 INF biosimilar prevalent users, 2,149 INF bio-originator naïve users, and 10,970 INF bio-originator prevalent users. The proportion of other biologic use prior to index date and demographic characteristics are similar across different cohorts with mean age of 45 and 60% females. Among patients who had >=12m of follow-up, 43% INF biosimilar naive users, 41.5% INF biosimilar prevalent users, 52% INF bio-originator  naïve users and 73% INF bio-originator  prevalent users continued to be adherent ( >80%) at 12 months. Among patients who had >=18m of follow-up, 48%, 36%, 41%, and 64% user continued to be adherent at 18 months respectively (Table).

Conclusion: The adherence patterns were similar among INF biosimilar naïve, INF biosimilar prevalent, and INF bio-originator naïve users. We found the INF bio-originator prevalent users had the highest adherence within 12 or 18 months of follow-up. However, further studies with large sample size are needed to evaluate the adherence of INF biosimilar users.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-adherence-patterns-among-patients-using-infliximab-bio-originator-and-biosimilar/