Cost-Effectiveness of Rituximab (Fixed-Schedule vs Tailored-Dose) Compared With Azathioprine Maintenance Therapy in Adults With Generalized Antineutrophil Cytoplasm Antibody-Associated Vasculitis in Colombia

Objectives: Azathioprine has been the therapy of choice for the maintenance of remission in patients with antineutrophil cytoplasm antibody (ANCA)-associated systemic vasculitis, but recent studies show that rituximab could be more effective. To evaluate the cost-effectiveness of azathioprine, fixed-schedule rituximab, and tailored-dose rituximab for ANCA-associated systemic vasculitis. Methods: A Markov model from the perspective of the Colombian healthcare system was designed with annual cycles and a 5-year time horizon, charting the following states: remission, minor relapse, major relapse, and death. The discount rate was 5%. Transition probabilities were obtained from a systematic literature review. The costs (1 US dollar = 2956 Colombian pesos in 2018) were estimated based on national drug registries and official fee manuals for procedures, along with other resources. The main outcomes were quality-adjusted life-years (QALYs) taken from the Tufts registry. Univariate and multivariate sensitivity analyses were performed. Results: Final costs were $1446 for azathioprine, $4898 for tailored-dose rituximab, and $6311 for fixed-schedule rituximab. QALYs gained were 3.18, 4.08, and 3.98, respectively. Rituximab was cost-effective (cost per incremental QALY gained: $4919, and $6865), and tailored-dose administration had a lower cost. Sensitivity analyses did not affect the results. Conclusions: Tailored-dose rituximab was the most cost-effective treatment for ANCA-associated vasculitis. Azathioprine presented worse effectiveness and lower cost, and fixed-schedule rituximab was dominated by tailored-dose rituximab.