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Reinitiation of Anticoagulation After Temporary Withdrawal of Vitamin K Antagonist (DOSIDO)

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: NCT01348074
Recruitment Status : Completed
First Posted : May 5, 2011
Last Update Posted : April 5, 2016
Information provided by (Responsible Party):
Sam Schulman, McMaster University

Brief Summary:
It is not known how to best restart warfarin after temporary withdrawal. Participants will be randomized to two groups. Group 1 will restart warfarin at their usual maintenance dose, group 2 will restart warfarin at double their maintenance dose for two days followed by their usual maintenance dose. The main outcome parameter will be the number of patients who are back in therapeutic INR (international normalized ratio) range 4, and 9 days after restarting anticoagulation with warfarin. Thromboembolic and/or bleeding events will be recorded as additional parameters. These data will be collected by a standardized telephone interview at 1 month. In addition, the investigators will evaluate a possible prothrombotic state by measuring the potential of thrombin generation and D-dimers in the subset of patients visiting HHS-General Hospital for their INR tests.

Condition or disease Intervention/treatment Phase
Atrial Fibrillation Venous Thromboembolism Heart Valve Disease Surgery Drug: Double dose Phase 2

Detailed Description:
We will investigate if it is feasible to use double maintenance dose for the first two administrations of vitamin K antagonists when these drugs were temporarily interrupted and thus keep the time of an increased risk of thromboembolism and duration of "bridging" at a minimum. The control group will consist of patients who resume vitamin K antagonists at their usual maintenance dose. The aim of the study is to establish how to best restart anticoagulation with vitamin K antagonists after temporal withdrawal of these drugs. The main outcome parameter will be the proportion of patients who are back to a therapeutic international normalized ratio (INR) ratio at certain days after restarting vitamin K antagonists. Two additional parameters will be evaluated: Firstly, bleeding and thromboembolic complications will be reported and secondly, a possible prothrombotic state, measured as an elevation of D-dimer, at the initiation of anticoagulation will be evaluated.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 104 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: Phase II Study of Double Versus Single Reinitiation Dose of Warfarin After Interruption for Surgery
Study Start Date : April 2011
Actual Primary Completion Date : December 2013
Actual Study Completion Date : December 2013

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Blood Thinners

Arm Intervention/treatment
Experimental: Double dose
Re-initiation with warfarin at twice the usual maintenance dose the first 2 days, then maintenance dose.
Drug: Double dose
For each individual the dose on Day 1 and Day 2 will be twice the one normally taken
Other Name: Loading dose

No Intervention: Usual maintenance dose
Usual maintenance dose from Day 1, i.e. no postoperative loading dose.

Primary Outcome Measures :
  1. Proportion of patients with INR back in therapeutic range Day 5 or Day 10 [ Time Frame: Day 5-10 ]
    Proportion of patients with INR 2.0-3.0 on Day 5 or Day 10 (day of invasive procedure defined as Day 1)

Secondary Outcome Measures :
  1. Thromboembolic events [ Time Frame: 30 days ]
    Objectively verified arterial or venous thromboembolic events

  2. Major bleeding events [ Time Frame: 30 days ]
    Defined by the ISTH criteria of 2010

  3. Minor bleeding events [ Time Frame: 30 days ]
    Any bleeding requiring medical attention but not fulfilling the criteria of Major bleeding

  4. Laboratory parameters of hypercoagulability [ Time Frame: 10 days ]
    Quantitative D-dimer and Thrombin Generation performed in a subset at day of procedure, day 5 and 10 to identify abnormal rise.

Information from the National Library of Medicine

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Ages Eligible for Study:   Child, Adult, Older Adult
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Current treatment with warfarin
  • Need for temporary interruption for invasive procedure or surgery

Exclusion Criteria:

  • Need for post-operative hospitalization more than one day
  • Participation in another clinical trial
  • No consent given

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): NCT01348074

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Canada, Ontario
Thrombosis Service, HHS- General Hospital
Hamilton, Ontario, Canada, L8L 2X2
Sponsors and Collaborators
McMaster University
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Principal Investigator: Sam Schulman, MD, PhD McMaster University
Additional Information:
Publications of Results:
Other Publications:
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Responsible Party: Sam Schulman, Prof., McMaster University Identifier: NCT01348074    
Other Study ID Numbers: HGH20090520
First Posted: May 5, 2011    Key Record Dates
Last Update Posted: April 5, 2016
Last Verified: April 2016
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No
Keywords provided by Sam Schulman, McMaster University:
Additional relevant MeSH terms:
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Atrial Fibrillation
Venous Thromboembolism
Heart Valve Diseases
Arrhythmias, Cardiac
Heart Diseases
Cardiovascular Diseases
Pathologic Processes
Embolism and Thrombosis
Vascular Diseases