Comparison of Utilization Trends between Biosimilars and Generics: Lessons from the Nationwide Claims Data in South Korea

Background: South Korea is unique in that it leads global markets in R&D as well as production of biosimilar products and was the first market into which some biosimilar products were introduced. We analyzed the time trend of market penetration and simulated saved spending by biosimilars in South Korea. Methods: We pulled Korean National Health Insurance claims data from January 2012–December 2018 for second-generation biologics, including infliximab, rituximab, and trastuzumab, and examined the time trends of expenditure, utilization in defined daily dose, and price. We also assessed market penetration by biosimilars and simulated expenditure savings gained due to their introduction. We comparatively examined time trends and spending savings during the same period for selected small-molecule generic drugs to understand any specifics limited to biosimilars for time trends of market share and quantity-standardized prices. Results: The market share for infliximab biosimilar plateaued at over 30%, which is smaller than the market penetration of esomeprazole (over 60%), a small-molecule comparator. Despite a shorter observation period, rituximab and trastuzumab biosimilars also showed larger utilization rates (12.89% and 13.93%, respectively) than infliximab (9.05%) in their second year after market entry. Infliximab was associated with approximately US $82–114 million expenditure savings over 6 years after its biosimilar entry to the market. Rituximab and trastuzumab biosimilars each also resulted in reduction in total spending by approximately US $9–14 million, in less than 2 years. Conclusion: Biosimilars captured the market rapidly, despite a heterogeneous uptake rate by product in South Korea. However, expansion of biosimilar use in the market and consequent expenditure savings need to be supported by pre-emptive policy measures to encourage price competition and boost utilization.