Anticoagulant therapy for symptomatic calf deep vein thrombosis (CACTUS): a randomised, double-blind, placebo-controlled trial.
BACKGROUND
The efficacy and safety of anticoagulant treatment is not established for patients with acute symptomatic deep vein thrombosis (DVT) of the calf. We aimed to assess whether therapeutic anticoagulation is superior to placebo in patients with symptomatic calf DVT.


METHODS
In this randomised, double-blind, placebo-controlled trial, we enrolled low-risk outpatients (without active cancer or previous venous thromboembolic disease) with a first acute symptomatic DVT in the calf from 23 university medical centres or community medical clinics in Canada, France, and Switzerland. We randomly assigned (1:1) patients to receive either the low-molecular-weight heparin nadroparin (171 UI/kg, subcutaneously, once a day) or placebo (saline 0·9%, subcutaneously, once a day) for 6 weeks (42 days). Central randomisation was done using a computer-generated randomisation list, stratified by study centre. Random allocation sequences of variable block size were centrally determined by an independent research clinical centre. Study staff, patients, and outcome assessors (central adjudication committee) were masked to group assignment. Numbered boxes of active drug or placebo were provided to pharmacies in identical packaging. All patients were prescribed compression stockings and followed up for 90 days. The primary efficacy outcome was a composite measure of extension of calf DVT to proximal veins, contralateral proximal DVT, and symptomatic pulmonary embolism at day 42 in the modified intention-to-treat population. The primary safety outcome was major or clinically relevant non-major bleeding at day 42. The trial was registered with ClinicalTrials.gov, number NCT00421538.


RESULTS
Between Feb 1, 2008, and Nov 30, 2014, we screened 746 patients, enrolling 259 patients (50% of the prespecified sample size), before the trial steering committee terminated the trial because of expiry of study drug and slow recruitment. The intention-to-treat analysis population comprised 122 patients in the nadroparin group and 130 in the placebo group. There was no significant difference between the groups in the composite primary outcome, which occurred in four patients (3%) in the nadroparin group and in seven (5%) in the placebo group (risk difference -2·1%, 95% CI -7·8 to 3·5; p=0·54). Bleeding occurred in five patients (4%) in the nadroparin group and no patients in the placebo group (risk difference 4·1, 95% CI 0·4 to 9·2; p=0·0255). In the nadroparin group one patient died from metastatic pancreatic cancer and one patient was diagnosed with heparin-induced thrombocytopenia type 2.


CONCLUSIONS
Nadroparin was not superior to placebo in reducing the risk of proximal extension or venous thromboembolic events in low-risk outpatients with symptomatic calf DVT, but did increase the risk of bleeding. Avoidance of systematic anticoagulation for calf DVT could have a substantial impact on individual patients and from a public health perspective.


BACKGROUND
Swiss National Science Foundation, the Programme Hospitalier de Recherche Clinique in France, and the Canadian Institutes of Health Research.
Division of Angiology and Hemostasis, Geneva University Hospital and Faculty of Medicine, Geneva, Switzerland. Electronic address: marc.righini@hcuge.ch.
Marc
M
Righini
Clinical Investigation Centre and Department of Internal and Vascular Medicine, Montpellier University Hospital, Montpellier, France.
Jean-Philippe
JP
Galanaud
Vascular Medicine Unit, Clinique Mégival, St Aubin sur Scié, France.
Hervé
H
Guenneguez
Clinical Investigation Centre and Department of Internal and Vascular Medicine, Montpellier University Hospital, Montpellier, France.
Dominique
D
Brisot
Vascular Medicine Unit, Langoiran, France.
Antoine
A
Diard
Vascular Medicine, Alès, France.
Pascale
P
Faisse
Vascular Medicine Unit, Caen University Hospital, Caen, France.
Marie-Thérèse
MT
Barrellier
Vascular Medicine Unit, Centre Hospitalier Privé Saint-Martin, Caen, France.
Claudine
C
Hamel-Desnos
Vascular Medicine Unit, Clinique du Tonkin, Villeurbanne, France.
Christine
C
Jurus
Vascular Medicine, Grenoble University Hospital, Grenoble, France.
Olivier
O
Pichot
Vascular Medicine, Annecy, France.
Myriam
M
Martin
Lausanne University Hospital, Lausanne, Switzerland.
Lucia
L
Mazzolai
Vascular Medicine, Le Robert, France.
Clarisse
C
Choquenet
Clinical Investigation Centre, Saint Etienne University Hospital, Saint Etienne, France.
Sandrine
S
Accassat
Division of Angiology and Hemostasis, Geneva University Hospital and Faculty of Medicine, Geneva, Switzerland.
Helia
H
Robert-Ebadi
Ottawa Health Research Institute, Ottawa, ON, Canada.
Marc
M
Carrier
Ottawa Health Research Institute, Ottawa, ON, Canada.
Grégoire
G
Le Gal
Division of Angiology and Hemostasis, Geneva University Hospital and Faculty of Medicine, Geneva, Switzerland.
Bernadette
B
Mermilllod
Clinical Investigation Centre and Department of Internal and Vascular Medicine, Montpellier University Hospital, Montpellier, France.
Jean-Pierre
JP
Laroche
Division of Angiology and Hemostasis, Geneva University Hospital and Faculty of Medicine, Geneva, Switzerland; Clinical Investigation Centre and Department of Internal and Vascular Medicine, Montpellier University Hospital, Montpellier, France.
Henri
H
Bounameaux
General Internal Medicine, Geneva University Hospital and Faculty of Medicine, Geneva, Switzerland.
Arnaud
A
Perrier
Department of Medicine and Lady Davis Institute, Jewish General Hospital, Montreal, QC, Canada.
Susan R
SR
Kahn
Clinical Investigation Centre and Department of Internal and Vascular Medicine, Montpellier University Hospital, Montpellier, France.
Isabelle
I
Quere
D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000009:adverse effects* / Q000627:therapeutic use*; D002170:Canada; D004311:Double-Blind Method; D057239:Early Termination of Clinical Trials; D005076:Exanthema / Q000139:chemically induced / Q000453:epidemiology; D005260:Female; D005602:France; D006470:Hemorrhage / Q000139:chemically induced / Q000453:epidemiology*; D006801:Humans; D007866:Leg / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D017762:Nadroparin / Q000009:adverse effects* / Q000627:therapeutic use*; D011655:Pulmonary Embolism / Q000453:epidemiology / Q000517:prevention & control*; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D055502:Secondary Prevention / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data*; D053828:Stockings, Compression; D013557:Switzerland; D013921:Thrombocytopenia / Q000139:chemically induced / Q000453:epidemiology; D016896:Treatment Outcome; D014463:Ultrasonography; D014680:Veins / Q000000981:diagnostic imaging / Q000503:physiopathology*; D020246:Venous Thrombosis / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000517:prevention & control*
D000925:Anticoagulants; D017762:Nadroparin