Fondaparinux Effective in Superficial-Vein Thrombosis

September 23rd, 2010

Fondaparinux Effective in Superficial-Vein Thrombosis

Larry Husten, PHD

In the randomized, double-blind CALISTO (Comparison of Arixtra in Lower Limb Superficial Vein Thrombosis with Placebo) trial, 3002 patients with acute, symptomatic superficial-vein thrombosis in the legs, but without DVT or symptomatic PE, received either fondaparinux (2.5 mg) or placebo for 45 days. The primary efficacy endpoint ─ a composite of all-cause death, symptomatic PE or DVT, symptomatic extension to the saphenofemoral junction, or symptomatic recurrence of superficial-vein thrombosis ─ was reduced by 85%: from 5.9% in the placebo group to 0.9% in the fondaparinux group (p<0.001). There was no difference between the groups in mortality. All the other components of the composite endpoint were significantly reduced by fondaparinux. In their report in the New England Journal of Medicine, the investigators calculated that 20 patients would need to be treated with fondaparinux to prevent 1 primary endpoint event, and 88 to prevent DVT or PE.

In an accompanying editorial, Lee Goldman and Jeffrey Ginsberg praise the conduct of the trial and note that fondaparinux, along with several other newer drugs, may be preferable to unfractionated heparin and warfarin. But, they warn, it is unclear whether the superior risk-benefit profile of the drug justifies the extra price. They recommend that the FDA mandate post-approval trials “to document the costs, the effects on quality of life, and the cost-effectiveness of new interventions.” Until these data are available, they write, “it would seem premature to recommend that fondaparinux be used routinely in the treatment of superficial-vein thrombosis.”

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September 23rd, 2010