According to the Comparison of Arixtra in Lower Limb Superficial Vein Thrombosis with Placebo (CALISTO) study, a recent randomized, controlled trial, prophylactic fondaparinux can prevent thrombotic complications following superficial vein thrombosis (SVT). The cost-effectiveness of this treatment remains to be determined.
We developed a decision-tree model comparing fondaparinux 2.5 mg daily for 45 days vs no treatment of SVT. It included all clinical events associated with SVT, its treatment, its complications, and all respective quality-adjustment factors. Data were mainly derived from the CALISTO study and the published literature. Measured outcomes comprised clinical events (VTE, major hemorrhage, death), quality-adjusted life-years (QALYs), costs, and incremental cost-effectiveness ratios (ICERs). The analysis was conducted using a lifetime time horizon from a health-care system perspective. We performed one-way and probabilistic sensitivity analyses to evaluate parameter uncertainty.
In 10,000 patients, we estimated that fondaparinux would prevent 123 VTE events and two deaths. On a per-patient basis, the incremental QALY compared with no treatment was 0.04 (1 day) at an incremental cost of $1,734, resulting in an ICER of $500,000 per QALY. This result remained robust in the one-way sensitivity analyses, with an ICER remaining > $100,000 per QALY throughout all ranges. Based on probabilistic sensitivity analyses, the probability that fondaparinux was cost-effective was 1% at a willingness-to-pay of $100,000 per QALY.
Fondaparinux for 45 days does not appear to be cost-effective when treating patients with isolated SVT of the legs. A better value for money could be obtained in subgroups of patients with a higher incidence of VTE after SVT. Shorter durations of treatment should be further evaluated in future clinical studies.