OBJECTIVES : Rheumatoid arthritis (RA) is associated with increased mortality and a severe impact on quality of life. This study estimates the impact of introducing a new Janus kinase (JAK) 1 inhibitor (filgotinib) into the Spanish healthcare system from a payer perspective over a 3-year horizon.

METHODS : A budget impact model was developed capturing healthcare costs over a 3-year horizon including for drug acquisition and administration (for reference drugs and biosimilars), disease-related adverse events, and hospital care. Two scenarios were compared: the current market with market share data taken from IQVIA survey and an alternative scenario where filgotinib was assumed to take an increasing proportion of the JAK inhibitors market with a maximum of 26.30% in year 3. JAK inhibitors as a proportion of the overall market were assumed to increase from 10.10% to 16.50%. Filgotinib’s overall market share was assumed to be 0.63%, 2.43%, and 4.34% in years 1, 2, and 3, respectively. Public list prices were used and the price of filgotinib assumed equal to tofacitinib. A range of scenarios were tested with price reductions for filgotinib and its comparators to explore the impact of discounting.

RESULTS : Adding filgotinib to the Spanish formulary was expected to result in annual savings of €13,171 in year 1, €96,177 in year 2, and €290,168 in year 3, with cumulative savings of €399,516. When applying discounts to the other drugs in scenario analyses, filgotinib continued to provide cumulative cost savings up to a discount on comparators of 7.5%.

CONCLUSIONS : The model predicted that introducing filgotinib for patients with RA in Spain led to reduced costs for the Spanish payer when using public list prices. Scenario analyses suggested that cost savings persisted when discounts were applied to comparators.

ACKNOWLEDGMENTS : Alexander van Doornewaard (HEOR Ltd, Cardiff, UK) contributed to the conception of this analysis.