OBJECTIVES: This study assessed the annual cost of biologic disease-modifying antirheumatic drugs (bDMARDs) used in rheumatoid arthritis (RA) treatment, evaluated the factors explaining annual cost at market entry, and examined the impact of biosimilar authorization on bDMARDs annual cost.

METHODS: The annual bDMARDs cost was calculated using wholesale acquisition cost prices (IBM Micromedex) at market entry and the FDA-recommended doses. Costs were adjusted to 2023 US dollars using the consumer price index. Descriptive statistics and regression analysis were performed. 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 annual cost at market entry was positively correlated with FDA approval dates (p=0.002) and TNFi classification (p=0.039). The annual cost at market entry for new bDMARDs exceeded the median annual cost for previous bDMARDs, except infliximab, adalimumab, and sarilumab. The FDA authorized 19 biosimilars for five bDMARDs as of December 31, 2023. 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 cost at market entry for all bDMARDs was $29,550 (IQR=$15,873). The median annual cost for bDMARDs with biosimilar competition ($23,700) was lower than for those without ($42,527). After standardization, the trend showed a significant increase in the annual treatment costs of TNFi bDMARDs and a substantial decrease following the FDA authorization of biosimilars for infliximab, rituximab, and adalimumab.

CONCLUSIONS: The annual cost at market entry of bDMARDs was associated with the approval date and pharmacological class. The FDA authorization of biosimilars significantly reduced the annual cost of bDMARDs used in RA treatment.