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Understanding Risk Factors Involved in Developing a Second Blood Clot.

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00261014
Recruitment Status : Unknown
Verified November 2015 by Ottawa Hospital Research Institute.
Recruitment status was:  Active, not recruiting
First Posted : December 2, 2005
Last Update Posted : November 18, 2015
Canadian Institutes of Health Research (CIHR)
Biomerieux inc
Heart and Stroke Foundation of Ontario
Information provided by (Responsible Party):
Ottawa Hospital Research Institute

Brief Summary:
The purpose of this study is to develop a way to predict which patients diagnosed with idiopathic blood clots can safely stop warfarin therapy after six months. We will use patient characteristics, blood test results and imaging test results to identify those patients who have the lowest risk of developing a new blood clot after warfarin is stopped.

Condition or disease
Deep Vein Thrombosis

Detailed Description:
The risk of recurrent VTE in patients with idiopathic VTE subsequent to three to six months of oral anticoagulant therapy remains high (5-27% per year). The risk of recurrent VTE, however, is not likely high enough to justify indefinite anticoagulation in all patients with a first idiopathic VTE due to the rate of major bleeding with oral anticoagulants (2-6% per year), the inconvenience and cost of oral anticoagulant therapy, monitoring of oral anticoagulant therapy (e.g. prescription costs, time off work to go for lab tests, parking etc) and the lifestyle limitations of oral anticoagulant therapy (avoidance of certain physical activities, dietary restrictions, avoidance of pregnancy). Further, as some have argued, perhaps all that anticoagulant therapy achieves is to delay recurrent VTE and, as a recent editorial suggested, a tailored approached is required to determine sub-groups who require lifelong anticoagulation. A means to stratify patients with idiopathic VTE to identify a group at low risk of recurrent VTE who could safely discontinue oral anticoagulants subsequent to six months of therapy would be a significant advance in the care of these patients.

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Study Type : Observational
Estimated Enrollment : 800 participants
Time Perspective: Prospective
Official Title: REcurrent VEnous Thromboembolism Risk Stratification Evaluation A Study to Develop a Clinical Prediction Rule to Predict Low Recurrence Risk in Patients With Idiopathic Venous Thromboembolism.
Study Start Date : October 2002
Estimated Primary Completion Date : March 2016
Estimated Study Completion Date : March 2016

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Blood Clots

Primary Outcome Measures :
  1. Incidence of adjudicated recurrent VTE during study follow-up [ Time Frame: 8 years ]

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Non-Probability Sample
Study Population
patients diagnosed with idiopathic blood clots

Inclusion Criteria:

  1. Objectively proven (as previously described (8)) proximal idiopathic deep vein thrombosis or pulmonary embolism. Idiopathic will be defined as VTE occurring in the absence of fracture, plaster cast, immobilization greater than 3 days or a general anesthetic in the last three months prior to VTE diagnosis; a known deficiency of antithrombin, protein C or protein S; and malignancy in the last five years
  2. Patients treated initially with a minimum of five days of heparin or low molecular weight heparin and oral anticoagulants with a target intensity of 2.0 - 3.0 with no recurrence in the subsequent six months.
  3. Patients currently on oral anticoagulants

Exclusion Criteria:

  1. Recurrent idiopathic VTE (i.e. ≥ 2 previous idiopathic VTE). Previous secondary VTE is not an exclusion criterion;
  2. Age <18;
  3. Known deficiency of proteins S, protein C or antithrombin;
  4. Known, persistently positive anticardiolipin antibodies (titers > 30U/ml);
  5. Known, persistently positive lupus anticoagulant;
  6. Combined thrombophilic defects (e.g. homozygous for FVL or PGM, or compound heterozygous for FVL and PGM);
  7. Refusal of informed consent.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00261014

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Canada, Nova Scotia
QE II Health Sciences Centre
Halifax, Nova Scotia, Canada, B3H 2Y9
Canada, Ontario
London Health Sciences Centre
London, Ontario, Canada, N6A 4G5
The Ottawa Hospital
Ottawa, Ontario, Canada, K1H 8L6
Canada, Quebec
Montreal General Hospital
Montreal, Quebec, Canada, H3G 1A4
Montreal Jewish General Hospital
Montreal, Quebec, Canada, H3T 1E2
Hopital du Sacre Coeur
Montreal, Quebec, Canada, H4J 1C5
CHU de le Cavale Blanche
Brest, France
Sponsors and Collaborators
Ottawa Hospital Research Institute
Canadian Institutes of Health Research (CIHR)
Biomerieux inc
Heart and Stroke Foundation of Ontario
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Principal Investigator: Marc Rodger, MD MSc OHRI
Publications automatically indexed to this study by Identifier (NCT Number):

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Responsible Party: Ottawa Hospital Research Institute Identifier: NCT00261014    
Other Study ID Numbers: 2002452-01H
First Posted: December 2, 2005    Key Record Dates
Last Update Posted: November 18, 2015
Last Verified: November 2015
Keywords provided by Ottawa Hospital Research Institute:
Deep Vein Thrombosis
Pulmonary Embolism
Clinical Prediction Rule
Venous Thromboembolism
Risk Factors
Additional relevant MeSH terms:
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Venous Thromboembolism
Venous Thrombosis
Embolism and Thrombosis
Vascular Diseases
Cardiovascular Diseases