A Cost-Effectiveness Analysis of Rivaroxaban Compared to Warfarin for the Management of Venous Thromboembolism in Western Kenya

BACKGROUND AND OBJECTIVE: Access to direct oral anticoagulants (DOACs) in sub-Saharan Africa is limited due to prohibitive upfront costs, making warfarin the standard of care for many patients, especially those relying on public-sector healthcare. This study evaluated the cost-effectiveness of using the DOAC, rivaroxaban, compared to warfarin for treating venous thromboembolism (VTE), a cardiovascular disorder caused by blood clots in the veins, in western Kenya. METHODS: We developed a discrete-time individual state-transition Markov model to simulate a VTE patient's quality-adjusted life-years (QALYs) and annual treatment costs under a rivaroxaban or warfarin therapy strategy. Transition state probabilities were derived from real-world event-rate data observed in patients treated with rivaroxaban (n = 160) or warfarin (n = 116) for VTE at Moi Teaching and Referral Hospital in western Kenya. Base-case parameter values were obtained from cohort event rates, local costs, and literature-derived utility values. Cost-effectiveness was assessed over a 1-year time horizon using an incremental cost-effectiveness ratio (ICER) threshold of (US)$6020.40 per QALY gained (equivalent to three times Kenya's 2021 per capita GDP). Deterministic and probabilistic sensitivity analyses were conducted to assess parameter and model uncertainty. RESULTS: After 12 months, total mean treatment costs per patient were $216.00 and $173.00 using warfarin and rivaroxaban, respectively. In the base-case analysis, rivaroxaban therapy resulted in an additional 0.023 QALYs per patient compared to warfarin, with an ICER of $- 1862.00 per QALY gained. Based on probabilistic sensitivity analysis with Monte Carlo simulation, when costs, utility values, and event rates were varied, rivaroxaban was cost-effective compared to warfarin in 84.1% of all simulations at a willingness-to-pay threshold of $6020.40 per QALY. One-way sensitivity analyses and scenario analyses were stable with rivaroxaban therapy, resulting in fewer costs and higher QALYs. CONCLUSIONS: In this study, rivaroxaban is a clinically and economically superior alternative to warfarin. This research may catalyze further discussions with policymakers and industry partners to scale up the appropriate use of rivaroxaban in resource-constrained settings.