Background/Purpose: Rheumatoid arthritis (RA) treatment has been revolutionized by the development of biologic disease-modifying antirheumatic drugs (bDMARDs), which are increasingly used. The high cost of bDMARDs is the major cost driver in RA management that affects RA treatment. This study assessed the annual cost of bDMARDs used in rheumatoid arthritis treatment, evaluated the factors explaining annual cost at market entry, and also examined the impact of biosimilar authorization on the annual cost of bDMARDs.

Methods: Regulatory information data and wholesale acquisition cost (WAC) for bDMARDs were extracted from the FDA databases and IBM Micromedex. The annual treatment for each bDMARD was estimated using the WAC prices at market entry and the FDA recommended dose. Costs were adjusted to 2023 US dollars with the consumer price index. We compared new bDMARDs costs per year at market entry with the median annual cost of marketed bDMARDs. We standardized costs to the year level to assess trends in annual treatment costs across pharmacological classes and bDMARDs with and without FDA biosimilar authorization.

Results: As of December 31, 2023, the FDA had approved ten bDMARDs for RA treatment in the US, five of which were in the TNFi classification. The FDA authorized 19 biosimilars for five bDMARDs. All nine biosimilars for adalimumab were marketed in 2023, and biosimilars for etanercept and tocilizumab had not yet entered the market in the US. The inflation-adjusted median annual treatment cost at market entry for all bDMARDs was $29,678 (IQR=$15,873). The median annual costs for bDMARDs with biosimilar competition ($23,700) were lower than those without ($42,527). The market entry annual cost for new bDMARDs exceeded the median for previous bDMARDs, except infliximab ($12,428), adalimumab ($23,802), and sarilumab ($42,710). After standardization, the trend revealed a significant increase in the costs of TNFi bDMARDs, with an average increase of 91% over the observed period and a substantial decrease following the FDA authorization of biosimilars for infliximab, rituximab, and adalimumab. A regression analysis indicated that the annual cost at market entry was significantly positively correlated with FDA approval dates (p=0.002) and TNFi classification (p=0.039).

Conclusion: The annual treatment cost at the market entry of bDMARDs was associated with the approval date and pharmacological class. Moreover, the evaluation of trends revealed a significant increase in the annual treatment costs of TNFi bDMARDs. The FDA authorization of biosimilars significantly reduced the annual cost of bDMARDs used in RA treatment.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/annual-cost-of-biologic-disease-modifying-antirheumatic-drugs-for-rheumatoid-arthritis/