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Abstract: SA-PO694

Economic Evaluation of Azathioprine vs. Rituximab in ANCA-Vasculitis in the United States

Session Information

Category: Glomerular Diseases

  • 1303 Glomerular Diseases: Clinical‚ Outcomes‚ and Trials

Authors

  • Ehlert, Lexy, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
  • Derebail, Vimal K., The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
  • Hogan, Susan L., The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
  • Aspinall, Sherrie L., VA Center for Health Equity Research and Promotion, Pittsburgh, Pennsylvania, United States
  • Thorpe, Carolyn T., The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
Background

Research indicates that rituximab (RTX) is superior to azathioprine (AZA) as a maintenance therapy in preventing relapse among patients in remission for ANCA-vasculitis (AV), including granulomatosis with polyangiitis, microscopic polyangiitis, and renal-limited disease. Some guidelines recommend RTX as first-line therapy, with AZA as second-line therapy. Because RTX is 15.5 times as expensive as AZA, we sought to evaluate the cost-effectiveness of RTX vs. AZA as a maintenance therapy in AV, from a U.S. payer, or health plan, perspective.

Methods

We used a 10-year Markov model with a hypothetical cohort of 10,000 patients. In this model, patients moved through four health states (see Figure). Model inputs included health state transition probabilities; probabilities of infection, cancer, and cardiovascular events; costs of treatment and outcomes; health state utility weights; and cost/utility discount rates. We did not include end-stage kidney disease, likely captured by relapse/death. Model outputs were years patients spent in relapse, deaths, costs, and quality-adjusted life-years (QALYs). We conducted a one-way sensitivity analysis to account for wide variation in medication costs.

Results

Therapy-specific results are reported in the Table. The incremental cost of RTX treatment was $171 million. The cost per major relapse year averted was $63,018 and the cost per death averted was $142,869. The cost per QALY gained was $43,936. In our one-way sensitivity analysis, we found that if payers pay 100% of the listed drug price, then the cost per QALY gained is ~$44,000. If drug costs can be reduced to 50% of current listed price, then the cost per QALY gained is ~$15,000.

Conclusion

Though RTX is associated with better health outcomes in this population, $44,000/QALY may be above the willingness-to-pay threshold for some U.S. payers. Efforts to reduce RTX cost can help payers stay within their WTP range and decrease overall healthcare spending.

Treatment ArmMinor Relapse YearsMajor Relapse YearsDeathsQALYs
Azathioprine4,99315,5302,10353,065
Rituximab5,04312,81390456,963