OBJECTIVES: Filgotinib is an orally administered preferential JAK1 inhibitor that has been shown to be effective in treating ulcerative colitis (UC). This study estimates the budget impact of introducing filgotinib as a new targeted synthetic UC treatment into the Spanish healthcare setting.

METHODS: A budget impact model was developed to capture health effects and direct healthcare costs from the perspective of the Spanish healthcare payer. The population of patients with moderately to severely active UC eligible for biologics and targeted synthetics was considered over a 5-year time horizon.

Two scenarios were modelled, one with current market share, and another in which filgotinib was introduced. Filgotinib market share was assumed to grow from 1.86% in year 2 following its introduction to 7.92% in year 5. UC prevalence and incidence in Spain was informed by two studies, Puig et al. (2019) and Chaparro et al. (2020).

Costs from 2021 incorporated in the model relate to UC treatment and disease management, including drug acquisition (using list prices) and administration, conventional therapy, disease state specific costs, surgery, and adverse event costs. Treatment cost calculations used standard Spanish dosing regimens, and biosimilar prices were used for treatments with loss of exclusivity. The price of filgotinib was €1,008 per pack. All model inputs were taken from published sources and verified by a Spanish clinician.

RESULTS: In the scenario with filgotinib, total cumulative cost savings of €27,928,217 were seen over 5 years. Drug acquisition costs accounted for cumulative savings of £25,877,947. An annual budget impact of −€2,413,031, −€4,580,980, −€8,396,296, and −€12,537,910 was estimated in years 2, 3, 4, and 5, respectively.

CONCLUSIONS: This study suggests that introducing filgotinib as a new treatment for UC would potentially lead to substantial cost savings to the Spanish healthcare system. The estimated budget impact could increase over 5 years as filgotinib gains market share.