OBJECTIVES: The antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) are a group of rare diseases, comprising granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic granulomatosis with polyangiitis (EGPA). AAV often leads to late diagnosis due to the non-specific disease course. Rapid disease progression leads to severe chronic organ damage and death. This analysis wants to evaluate avacopan (AVA) in combination with either a rituximab (RTX) or cyclophosphamide (CYC) dosing regimen, compared to prednisolone plus RTX or CYC in adult patients with severe active GPA or MPA.

METHODS: A multistate Markov-cohort-model was developed to simulate costs, life-years (LYs) and quality-adjusted life-years (QALYs) with a lifetime horizon. The model comprises 9 health states: an active disease state, three remission and three relapse states, end-stage renal disease (ESRD) and death, with a cycle length of 4 weeks. The clinical data come from the phase 3 clinical trial ADVOCATE. Direct costs (year 2024) were derived from published sources. All drug costs, including avacopan, are based on the reimbursement list-price. A univariate deterministic sensitivity analysis and probabilistic sensitivity analysis (PSA) were performed. QALYs, LYs and costs were discounted.

RESULTS: Over a lifetime horizon, the average total cost per patient was 356,457€ for AVA+RTX/CYC versus 317,579€ for prednisolone+RTX/CYC. Furthermore, treatment with AVA+RTX/CYC was associated with an incremental QALY benefit of 0.67 QALYs (6.34 versus 5.67). This led to an ICUR of 57,684€. Avacopan was also associated with lower life-years spent in ESRD (6.18 years vs. 7.16 years) leading to a potential cost-saving of 48,385€ per patient The model results were sensitive to the discount rate for outcomes, the cost of dialysis and relative risk of death.

CONCLUSIONS: In adult patients with this rare and severe active condition (AAV), Avacopan shows a good and affordable cost-effectiveness relationship from the Austrian payer perspective.