S297: ASSESSING THE COST-EFFECTIVENESS OF LONG-TERM PROPHYLAXIS STRATEGIES IN VON WILLEBRAND DISEASE

Abstract

Background: Von Willebrand disease (vWD) is the most common inherited bleeding disorder. Patients with vWD may experience excessive bleeding events resulting in morbidity, reduced quality of life, and a substantial economic burden. Management strategies include von Willebrand factor concentrates either as on-demand treatment (ODT) of bleeds or long-term prophylaxis (LTP) to prevent bleeds. According to recent treatment guidelines, long-term prophylaxis is recommended in individuals with severe and frequent bleeds. Aims: To assess the cost effectiveness of ODT and LTP treatment strategies in vWD patients with low, medium and high annual bleed rate (ABR), using pdVWF/FVIII 2,4:1 products (2,4:1 product A in the United Kingdom (UK) and 2,4:1 product B in Sweden). Methods: A Markov structure considering risk of joint surgery and bleed rate was used to estimate the life years (LYs), quality-adjusted life years (QALYs), and costs of vWD treatment over a lifetime horizon. Treatment options included ODT or LTP with pdVWF/FVIII 2,4:1 or pdVWF/FVIII 1:1 in the UK and in Sweden. Product dosing for LTP and for ODT were obtained from each product’s summary of product characteristics or assumed equal to similar products where data are not available. Bleed risks (major and minor bleed) were estimated for each product in ODT and LTP using published prophylaxis studies and were used to estimate costs of product needed and to determine the probability of requiring joint surgery over time based on the progression of Pettersson Score. Resource use (inpatient and outpatient) costs for bleeds and joint surgery were obtained from standard country-specific costing sources. All costs are shown in 2021 GBP or Swedish Kr for the UK and Swedish analyses, respectively. Health-state utility weights and disutilities of bleeds were obtained from published literature. Annual discount rates for costs and outcomes were 3.5% for the UK and 3% for Sweden. One-way and probabilistic sensitivity analyses were conducted to evaluate the impact of parameter uncertainty. Each analysis considered a low, medium, and high ABR patient population. Results: In the base case analyses (medium ABR) over a lifetime horizon, pdVWF/FVIII 2,4:1 LTP regimens were cost-effective compared with ODT. For pdVWF/FVIII 2,4:1 in the UK, LTP was both cost-saving (-£831,206 incremental cost) and more effective (6.14 incremental QALY) than ODT. Costs of bleed events more than offset the costs of prophylaxis. In Sweden with pdVWF/FVIII 2,4:1, LTP was also dominant (-8,841,901 kr; 6.52 QALY) compared with ODT. In comparisons of LTP regimens, pdVWF/FVIII 2,4:1 was dominant versus pdVWF/FVIII 1:1 in both the UK (-£2,307,370; 1.56 QALY) and in Sweden (-21,939,947 kr; 1.42 QALY). In comparison of ODT regimens, pdVWF/FVIII 2,4:1 was less expensive than pdVWF/FVIII 1:1 in the UK (-£1,250,369; equal QALY) and in Sweden (-7,923,741 kr; equal QALY) due to differences in product costs. Results were similar for comparisons in the high ABR populations. In probabilistic sensitivity analyses, pdVWF/FVIII 2,4:1 was dominant in over 95% of simulations in the UK and in over 85% of simulations in Sweden, and was cost-effective in 95% or more of simulations in both countries. Summary/Conclusion: These results suggest that LTP with pdVWF/FVIII 2,4:1 is a cost-effective strategy compared with ODT, in both the UK and Sweden, for medium and high ABR vWD patients. pdVWF/FVIII 2,4:1 was shown to be cost-effective compared with pdVWF/FVIII 1:1 in the LTP setting, as well as less costly for patients treated ODT for both the UK and Swedish settings, respectively.