The US Food and Drug Administration is considering an application for a biosimilar version of infliximab, which has been available in South Korea since November 2012. The aim of the present study was to examine the utilization patterns of both branded and biosimilar infliximab and other tumor necrosis factor (TNF) inhibitors in South Korea before and after the introduction of this biosimilar infliximab.
Using claims data from April 2009 to March 2014 from the Korean Health Insurance Review and Assessment Service database, which includes the entire South Korean population, the number of claims for biosimilar infliximab was assessed. A segmented linear regression model was used to examine the utilization patterns of infliximab (the branded and biosimilar versions) and other TNF inhibitors (adalimumab and etanercept) before and after the introduction of the biosimilar infliximab.
In total, 20,976 TNF inhibitor users were identified from the South Korean claims database, including 983 with a prescription claim for biosimilar infliximab. Among all of the claims for any version of infliximab, the proportion of biosimilar infliximab claims increased to 19% through March 2014. Before November 2012, each month there were 33 (95% confidence interval [95% CI] 32, 35) more infliximab claims, 44 (95% CI 40, 48) more etanercept claims, and 50 (95% CI 47, 53) more adalimumab claims. After November 2012, there were significant changes in the slopes for trend in usage, with additional increases in the use of branded and biosimilar infliximab (9 more claims per month, 95% CI 2, 17) and decreases in the use of etanercept (-52 claims per month, 95% CI -66, -38) and adalimumab (-21 claims per month, 95% CI -35, -6).
During the first 15 months since its introduction in South Korea, one-fifth of all infliximab claims were for the biosimilar version. Introduction of biosimilar infliximab may affect the use of other TNF inhibitors, and the magnitude of change in usage will likely differ in other countries.