Comparison of Arixtra in Lower Limb Superficial Vein Thrombosis With Placebo - CALISTO


The goal of the trial was to evaluate treatment with the factor Xa inhibitor fondaparinux (arixtra) compared with placebo among patients with acute symptomatic superficial-vein thrombosis of the legs.


Fondaparinux will be more effective at preventing venous thromboembolic complications.

Study Design

  • Blinded
  • Placebo Controlled
  • Randomized
  • Parallel

Patient Populations:

  • Patients at least 18 years of age with an acute symptomatic superficial-vein thrombosis of the lower legs

    Number of enrollees: 3,002
    Duration of follow-up: 77 days
    Mean patient age: 57 years
    Percentage female: 65%


  • More than 3 weeks between symptoms and intended randomization
  • Cancer within the last 6 months
  • Deep vein thrombosis or pulmonary embolism
  • Superficial-vein thrombosis associated with sclerotherapy or indwelling catheter
  • Superficial-vein thrombosis within the last 3 months
  • Deep-vein thrombosis or pulmonary embolism within the last 6 months
  • Use of antithrombotic agent for >48 hours or nonsteroidal anti-inflammatory agent for >72 hours prior to admission
  • Major surgery within last 3 months
  • Significant liver disease, renal disease, or thrombocytopenia
  • Women of childbearing age not using reliable contraception

Primary Endpoints:

  • Composite of all-cause death or venous thromboembolic complications defined as symptomatic pulmonary embolism, symptomatic deep-vein thrombosis, symptomatic extension to the saphenofemoral junction, or symptomatic recurrence of superficial-vein thrombosis up to day 47

Secondary Endpoints:

  • Major bleeding

Drug/Procedures Used:

Eligible patients with superficial-vein thrombosis of the lower legs were randomized to fondaparinux 2.5 mg subcutaneous daily for 45 days (n = 1,502) versus placebo (n = 1,500).

Concomitant Medications:

Patients were allowed to take acetaminophen or topical nonsteroidal anti-inflammatory agents during the study period.

Principal Findings:

Overall, 3,002 patients were randomized. In the fondaparinux group, the mean age was 57 years, 65% were women, mean body mass index was 29 kg/m2, 89% had a history of superficial-vein thrombosis, at inclusion 75% were using graduated compression stockings, and 23% were using aspirin or another antiplatelet agents.

The primary efficacy outcome, all-cause death or venous thromboembolic complications, occurred in 0.9% of the fondaparinux group versus 5.9% of the placebo group (p < 0.001). Death occurred in 0.1% versus 0.1%, pulmonary embolism in 0% versus 0.3% (p = 0.03), deep-vein thrombosis in 0.2% versus 1.2% (p < 0.001), extension of superficial-vein thrombosis in 0.3% versus 3.4% (p < 0.001), and recurrence of superficial-vein thrombosis in 0.3% versus 1.6% (p < 0.001), respectively.

Major bleeding occurred in 0.1% versus 0.1% (p = 1.0), and serious adverse events occurred in 0.7% versus 1.1% (p = NS), respectively.


Among patients with acute symptomatic superficial-vein thrombosis of the lower legs, the use of fondaparinux was beneficial. Fondaparinux compared with placebo was effective at reducing the composite primary outcome, which included various manifestations of venous thromboembolic complications. Placebo was selected for the control arm since no standard treatment for superficial-vein thrombosis existed at the time of the trial. All components of the primary outcome were reduced with fondaparinux except mortality. This novel agent appeared well tolerated, with similar bleeding and serious adverse events compared with placebo.


Decousus H, Prandoni P, Mismetti P, et al. Fondaparinux for the treatment of superficial-vein thrombosis in the legs. N Engl J Med 2010;363:1222-32.

Clinical Topics: Anticoagulation Management, Dyslipidemia, Vascular Medicine, Atherosclerotic Disease (CAD/PAD), Lipid Metabolism, Novel Agents

Keywords: Polysaccharides, Platelet Aggregation Inhibitors, Stockings, Compression, Pulmonary Embolism, Venous Thrombosis, Factor Xa, Leg, Peripheral Vascular Diseases

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