Biological disease-modifying antirheumatic drugs (bDMARDs) are effective but expensive options for treating rheumatoid arthritis. The introduction of infliximab and etanercept biosimilars presents a significant potential cost saving in a financially constrained health system such as the National Health Service (NHS) in the UK. This study examines the impact of the introduction of infliximab and etanercept biosimilars on the utilisation of bDMARDs and subsequent budget impact.
We conducted an interrupted time series analysis of secondary care utilisation data in rheumatology specialities from the DEFINE database, between March 2014 and February 2017.
The cumulative cost savings from the introduction of infliximab and etanercept biosimilars was £38.8 million over 2 years. There was a statistically significant increase in average monthly utilisation of bDMARDs for adalimumab (0.48%), certolizumab pegol (1.90%), golimumab (3.06%), abatacept (2.97%) and tocilizumab (2.24%), but not for etanercept. In contrast, the overall utilisation of infliximab decreased slightly by an average of 0.03% per month. The introduction of infliximab biosimilars negatively affected the monthly utilisation of branded infliximab significantly. Similarly, the introduction of an etanercept biosimilar negatively affected the monthly utilisation of branded etanercept significantly.
The introduction of bDMARDs biosimilars has resulted in considerable cost savings to the NHS, with the branded products reducing their prices in response to the availability of less expensive biosimilars and competition between the biosimilars themselves. Our results also suggest that when a biosimilar is available for a directly comparable branded molecule, price is the key influencing factor in the prescribing of a specific product.