The biosimilar shift: trending infliximab biosimilar utilization and associated cost savings for commercial insurance

To evaluate the effects of the introduction of infliximab biosimilars on the cost of infliximab originator, the associated cost savings with infliximab biosimilars, and the market utilization of infliximab products in the first 5 years after infliximab biosimilars became available in the US.

Retrospective longitudinal analysis.

A retrospective longitudinal analysis with an interrupted time series analysis was performed using the Merative MarketScan Commercial Claims and Encounters Database for outpatient infliximab claims from January 1, 2015, to December 31, 2021, for patients aged 0 to 64 years with commercial insurance. Outcomes of interest included market share of all infliximab products, cost per vial and infusion, and projected cost savings to the health care system after adjusting for inflation using the US Bureau of Labor Statistics Consumer Price Index for medical care.

A total of 471,731 claims from 42,099 unique patients met the inclusion criteria. Using an interrupted time series analysis, there was a 13-month lag before infliximab biosimilar utilization began to affect originator drug cost. Infliximab utilization increased to 26% by December 2021, and the price per infusion and per vial of infliximab originator decreased by 53% and 62%, respectively, from December 2017 to December 2021. The introduction of infliximab biosimilars has saved the US health care system an estimated $260 million to $842 million.

Utilization of infliximab biosimilars steadily increased in the first 5 years after market entry. The competition created by biosimilars has contributed to significant health care savings and a decrease in the total cost of both the infliximab originator drug and its biosimilars.