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Understanding Risk Factors Involved in Developing a Second Blood Clot.

This study is ongoing, but not recruiting participants.
Canadian Institutes of Health Research (CIHR)
Biomerieux inc
Heart and Stroke Foundation of Ontario
Information provided by (Responsible Party):
Ottawa Hospital Research Institute Identifier:
First received: November 30, 2005
Last updated: November 17, 2015
Last verified: November 2015
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.

Deep Vein Thrombosis

Study Type: Observational
Study Design: 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.

Resource links provided by NLM:

Further study details as provided by Ottawa Hospital Research Institute:

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

Estimated Enrollment: 800
Study Start Date: October 2002
Estimated Study Completion Date: March 2016
Estimated Primary Completion Date: March 2016 (Final data collection date for primary outcome measure)
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.

Ages Eligible for Study:   18 Years and older   (Adult, Senior)
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.
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Please refer to this study by its identifier: NCT00261014

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
Principal Investigator: Marc Rodger, MD MSc OHRI
  More Information

Publications automatically indexed to this study by Identifier (NCT Number):

Responsible Party: Ottawa Hospital Research Institute Identifier: NCT00261014     History of Changes
Other Study ID Numbers: 2002452-01H
Study First Received: November 30, 2005
Last Updated: November 17, 2015

Keywords provided by Ottawa Hospital Research Institute:
Deep Vein Thrombosis
Pulmonary Embolism
Clinical Prediction Rule
Venous Thromboembolism
Risk Factors

Additional relevant MeSH terms:
Venous Thromboembolism
Venous Thrombosis
Embolism and Thrombosis
Vascular Diseases
Cardiovascular Diseases processed this record on April 26, 2017