Cost-Effectiveness of Defibrotide for the Treatment of Veno-Occlusive Disease/Sinusoidal Obstruction Syndrome (VOD/SOS) with Multi-Organ Dysfunction (MOD) Post-Hematopoietic Stem Cell Transplantation (HSCT) in Canada
Authors: Belsey Jonathan , Kemadjou Eric Ngonga , Isaila Maya , Villa Kathleen F. 
Published: October 2019

Abstract
Introduction
Hepatic VOD/SOS is a progressive, potentially life-threatening complication of conditioning for HSCT or of nontransplant-associated chemotherapy. Without treatment VOD/SOS with MOD (eg, renal and/or pulmonary dysfunction) may be associated with >80% mortality. Defibrotide (DF) is approved to treat hepatic VOD/SOS with renal and/or pulmonary dysfunction post-HSCT in the United States and Canada, and to treat severe hepatic VOD/SOS post-HSCT in patients aged >1 month in the European Union. The current analysis evaluates the cost-effectiveness of DF vs best supportive care (BSC) in Canada in patients with VOD/SOS with MOD post-HSCT.
Methods
A previously reported global Markov cost-utility model was adapted to reflect Canadian sources of care with regard to epidemiology, management costs, and survival expectancy; only direct medical costs were included. The model included an acute phase and a long-term phase, with a lifetime horizon. Transition probabilities in the acute phase were based on Phase 3 (Richardson et al, 2016) endpoints of Day +100 survival and complete response (CR). The model included 4 health states: severe VOD/SOS, CR, survival, and death. Survival in the long-term phase was extrapolated using Remberger et al (2011) and Ashton et al (2014).
Hospital costs were calculated by taking the difference in time to CR in each arm in order to estimate the expected difference in hospital days between the BSC and DF arms. The severe VOD/SOS utility value was assumed to be the same as acute liver failure and end-stage liver disease scores (0.208), and the utility for CR was set to the age-matched general population. Costs and outcomes were discounted at 1.5% per year according to government guidance. Health effects were primarily expressed in terms of quality adjusted life years (QALYs).
Results
The difference in estimated costs between DF and BSC was $27,396 (Canadian dollars; Table). DF showed an increase in 1.5 QALYs versus BSC. The incremental cost-effectiveness ratio (ICER; cost per QALY gained) was $17,724. In the probabilistic sensitivity analysis, for willingness to pay of $30,000 and $50,000 per QALY gained, the probabilities of DF being cost-effective were 85.6% and 100%, respectively (Figure).
Conclusion
These results suggest that DF treatment for VOD/SOS with MOD represents cost-effective use of health resources in Canada, with an ICER estimate compared with BSC that was below the accepted willingness to pay threshold. Limitations of the analysis include longer-term extrapolation of clinical trial data and assumptions about resource utilization patterns. Results were driven by estimates of more rapid recovery, reduced length of stay, and improved Day +100 survival in DF-treated patients. Results were supported by the sensitivity analysis.
Support: Jazz Pharmaceuticals.

Disclosures
Belsey: Jazz Pharmaceuticals: Consultancy. Kemadjou:Jazz Pharmaceuticals: Consultancy. Isaila:Jazz Pharmaceuticals: Employment, Other: Stock and stock options. Villa:Jazz Pharmaceuticals: Employment, Equity Ownership, Other: Stock and stock options.