Does Low Dose Oral Vitamin K Improve International Normalized Ratio (INR) Stability? (OVWAC VII)

This study is ongoing, but not recruiting participants.
Sponsor:
Collaborators:
McMaster University
University of Western Ontario, Canada
Information provided by (Responsible Party):
Mark Crowther, St. Joseph's Healthcare Hamilton
ClinicalTrials.gov Identifier:
NCT00990158
First received: October 5, 2009
Last updated: December 9, 2013
Last verified: December 2013
  Purpose

Warfarin is highly effective for the prevention of both first and recurrent thrombotic events, however even minor excursions outside the reference INR range of 2.0 to 3.0 are associated with bleeding or thrombotic complications. The importance of maintaining the INR within the desired interval has led to the concept of "time in therapeutic range (TTR)" - the total proportion of time that the INR is between 2.0 and 3.0. The investigators propose a multicentre, double blind, randomized trial which will determine if 0.150 mg of oral vitamin K increases time in the therapeutic range for patients receiving warfarin.


Condition Intervention Phase
Coagulation
Bleeding
Thrombosis
Drug: Phytonadione (Vitamin K1)
Drug: Placebo
Phase 3

Study Type: Interventional
Study Design: Allocation: Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Parallel Assignment
Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: A Multicentre Study of Low Dose Oral Vitamin K for INR Control in Patients Receiving Warfarin

Resource links provided by NLM:


Further study details as provided by St. Joseph's Healthcare Hamilton:

Primary Outcome Measures:
  • When compared with placebo does the addition of 150 micrograms of daily vitamin K to "usual warfarin therapy" improve anticoagulant control as measured by "time in the therapeutic range"? [ Time Frame: 7 Months ] [ Designated as safety issue: Yes ]

Secondary Outcome Measures:
  • Does low dose Vitamin K (LDVK) increase the frequency of adverse clinical events, including thromboembolism and major and/or all bleeding? [ Time Frame: 7 Months ] [ Designated as safety issue: Yes ]

Estimated Enrollment: 400
Study Start Date: July 2010
Estimated Study Completion Date: April 2014
Estimated Primary Completion Date: April 2014 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: Low dose vitamin K + usual warfarin
Low dose oral vitamin K (0.150 mg orally once daily) + warfarin continuation with usual warfarin monitoring
Drug: Phytonadione (Vitamin K1)
A daily dose of 150 micrograms of vitamin K medication given orally for a total of 7 months
Placebo Comparator: Usual warfarin therapy + placebo
Patients continue usual warfarin and take one placebo per day
Drug: Placebo
A daily dose of matching placebo medication given orally for a total of 7 months

  Show Detailed Description

  Eligibility

Ages Eligible for Study:   18 Years and older
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No
Criteria

Inclusion Criteria:

  • Warfarin therapy administered to a target INR of 2.0 to 3.0

Exclusion Criteria:

  • Out of range INR on day of screening - enrolment will only occur if the patient's INR on the day of screening is between 1.8 and 3.4 (inclusive) - if the INR is outside this range the patient will be re-screened when the INR is within this range.
  • Recent warfarin initiation - all patients must have received warfarin for a minimum of 3 months
  • Planned termination or extended temporary interruption of warfarin within 6 months or anticipated survival of less than 6 months
  • Known severe liver disease, known excess alcohol consumption , known malabsorption syndrome or inability to take oral medications
  • Use of medications known to interfere with warfarin and whose dose is likely to change over the course of the study (e.g. barbiturates, rifampin etc.)
  • Known allergy to vitamin K
  • Inability or unwillingness to follow study procedures or provide consent
  • Prior participation in this study, or participating in a competing study which may impact INR control
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00990158

Locations
Canada, Ontario
St. Joseph's Hospital
Hamilton, Ontario, Canada, L8N 4A6
Hamilton Health Sciences Centre
Hamilton, Ontario, Canada, L8L 2X2
London Health Sciences Centre
London, Ontario, Canada, N6A 4G5
University Health Network, Toronto General Hospital
Toronto, Ontario, Canada, M5G 2C4
Sponsors and Collaborators
St. Joseph's Healthcare Hamilton
McMaster University
University of Western Ontario, Canada
Investigators
Principal Investigator: Mark A Crowther, MD McMaster University
  More Information

Additional Information:
Publications:
de Assis MC, Rabelo ER, Avila CW, Polanczyk CA, Rohde LE. Improved Oral Anticoagulation After a Dietary Vitamin K-Guided Strategy: A Randomized Controlled Trial. Circulation 2009 Sep 22;120(12):1115-22.
Crowther MA, Ageno W, Garcia D, Wang L, Witt DM, Clark NP, et al. Effectiveness of low dose oral vitamin K for patients with elevated INR values: results of a randomized trial examining clinical outcomes. Journal of Thrombosis & Haemostasis 5[S2], PS 219. 2008.

Responsible Party: Mark Crowther, Vice President, Research, St. Joseph's Healthcare Hamilton
ClinicalTrials.gov Identifier: NCT00990158     History of Changes
Other Study ID Numbers: NA 6695
Study First Received: October 5, 2009
Last Updated: December 9, 2013
Health Authority: Canada: Health Canada

Keywords provided by St. Joseph's Healthcare Hamilton:
Vitamin K1 (phytonadione)
Randomized controlled trial
Warfarin
Coagulopathy
Time in therapeutic range
Bleeding
Thrombosis
VKORC1 and CYP2C9 genotypes
Time INR in therapeutic range

Additional relevant MeSH terms:
Thrombosis
Embolism and Thrombosis
Vascular Diseases
Cardiovascular Diseases
Vitamins
Vitamin K
Vitamin K 1
Warfarin
Micronutrients
Growth Substances
Physiological Effects of Drugs
Pharmacologic Actions
Antifibrinolytic Agents
Fibrin Modulating Agents
Molecular Mechanisms of Pharmacological Action
Hemostatics
Coagulants
Hematologic Agents
Therapeutic Uses
Anticoagulants

ClinicalTrials.gov processed this record on October 19, 2014