OBJECTIVES: This study evaluates the budget impact of introducing filgotinib, a selective JAK1 inhibitor, as a first-line advanced treatment for patients with moderate to severe active rheumatoid arthritis (RA) who had an inadequate response disease-modifying antirheumatic drugs (DMARDs)in Greece, from a third-party payer perspective.

METHODS: To assess the budget impact of introducing filgotinib for RA in Greece, we adapted an existing pharmacoeconomic model, using cost data referring to the year 2023 collected through official resources. The analysis compares two scenarios over a five-year horizon starting from 2023: a "World without Filgotinib", reflecting current RA management practices, and a "World with filgotinib", to estimate post-introduction economic implications. This budget impact analysis evaluates direct medical costs including pharmaceuticals, administration, monitoring, hospitalization, and adverse event management, providing a detailed financial assessment of integrating filgotinib into RA treatment strategies in Greece.

RESULTS: Introduction of filgotinib is projected to result in substantial annual savings for third-party payers, with the peak savings reaching €235,767 by 2027. Initially, in 2023, filgotinib's market impact is negligible due to its zero-market share. Starting in 2024, as filgotinib's market share increases, significant savings accrue, primarily by replacing more expensive biologic DMARDs. Notably, costs associated with hospital care and adverse events remain stable across all treatment options. The cumulative five-year savings are estimated at €548,258. Filgotinib's oral administration also significantly lowers administration costs compared to other treatments requiring hospital-based administration. A deterministic sensitivity analysis emphasized the pivotal role of market share in determining the budget impact, consistently showing savings under scenarios where filgotinib's cost is lower.

CONCLUSIONS: The introduction of filgotinib offers significant potential for cost savings to third-party payers primarily by reducing drug acquisition and administration expenses. This analysis highlights filgotinib's valuable economic benefits, positioning it as an advantageous option for RA management within financially constrained healthcare systems.