Nationwide Trends and Cost Implications of Switching Between Infliximab Products

The introduction of infliximab biosimilars in the US has helped curb health care costs through competitive pricing. Many insurance payers have mandated switches from the originator to an infliximab biosimilar citing cost savings. This study assessed the cost savings to insurance payers and patients associated with switching infliximab products using a commercial claims database.

This is a retrospective cohort study of commercially insured patients who received multiple infliximab products between 2015 and 2021 using administrative claims data.

Infliximab outpatient claims from 2015 to 2021 were reviewed using the Merative MarketScan Commercial Claims and Encounters Database. Patients who switched infliximab products were identified by changes in Current Procedural Terminology codes. Cost savings to insurance payers and patients were calculated with infliximab product switches.

A total of 1785 patients underwent at least 1 infliximab product switch, with the majority occurring in 2021. Of the first-time switches, 92% (n = 1642) were from the infliximab originator to a biosimilar, with 72% (n = 1286) switching to infliximab-dyyb (Inflectra; Celltrion, Inc). Thirteen percent (n = 232) underwent 2 or more switches. Insurance payers saw a peak savings from product switching in 2019, with a median (IQR) of $1088 ($612-$1888) saved per infusion. Savings decreased to $61 (-$321 to $639) per infusion in 2021. Median patient out-of-pocket savings remained $0 throughout the study.

Switching to infliximab biosimilars increased over the study period. Cost savings for insurers peaked in 2019 but were negligible by 2021. Patients did not experience any savings from switching. Because nonmedical switching burdens providers and risks patient harm without clear economic benefits, mandatory switches demand greater system transparency to prioritize patient welfare.