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Abstract: PO1934

Cost-Effectiveness of Maintenance Therapy with Azathioprine vs. Rituximab (Tailored or Fixed-Schedule) in Adults with Generalized ANCA Vasculitis in Colombia

Session Information

Category: Glomerular Diseases

  • 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Contreras, Kateir, Hospital Universitario San Ignacio, Bogota, Colombia
  • Orozco Ortiz, Viviana, Hospital Universitario San Ignacio, Bogota, Colombia
  • Puche Carrascal, Eduardo José, Hospital Universitario San Ignacio, Bogota, Colombia
  • Garcia, Paola, Hospital Universitario San Ignacio, Bogota, Colombia
  • Gonzalez, Camilo A., Hospital Universitario San Ignacio, Bogota, Colombia
  • Rodriguez, Patricia, Hospital Universitario San Ignacio, Bogota, Colombia
  • Rosselli, Diego, Hospital Universitario San Ignacio, Bogota, Colombia
Background

Azathioprine has been the drug of choice for maintenance therapy in patients with generalized ANCA vasculitis. However, recent studies show that rituximab, a high-cost biological agent, which can be administrated in two different schedules, might be more effective, so it is necessary to know the cost- effectiveness. Our goal was to compare the cost-effectiveness of the 3 maintenance schemes: standard therapy with azathioprine; fixed-dose rituximab and rituximab tailored according to CD19 lymphocyte level and ANCA titres, from the perspective of the Colombian healthcare system.

Methods

We designed a 5-year annual cycle Markov model with the following stages: remission, minor relapse, mayor relapse and death. Transition probabilities were obtained from a systematic review of the literature (Scopus and Pubmed). Following national guidelines for economic studies, costs, in 2018, 1USD = 2.956 Colombian pesos (COP), were estimated based on national drug registries, and official tariff manuals for procedures and other resources. Main outcome was quality-adjusted life years (QALY), using lupus nephropathy as a proxy; values were obtained from Tufts CEA Registry and validated by local expert panel through a modified Delphi technique. Cost-effectiveness threshold was three-times per capita GDP (USD 17253). Discount rate was 5%. Univariate and probabilistic sensitivity analyses were performed.

Results

Overall discounted 5-years costs were USD 1356 for azathioprine; USD 4750 for tailored rituximab and USD 6162 for fixed rituximab. QALY gains were 2.94, 3.63 and 3.64, respectively. Both tailored and fixed rituximab were cost-effective (cost per QALY gained: USD 4.919 and USD 6.865 respectively), but tailored dosing was preferable due to its lower cost. Sensitivity analyses did not modify these results significantly.

Conclusion

To our knowledge this is the first economic evaluation that compare azathioprine with tailored and fixed rituximab regimens as a vasculitis maintenance treatment in adults with ANCA generalized. Due to its lower effectiveness azathioprine should not be the first line of treatment. Tailored rituximab should be a better option than fixed schedule due to its lower cost with similar effectiveness.