- ICH GCP
- US Clinical Trials Registry
- Clinical Trial NCT00794755
Low Dose Supplementation to Improve Anticoagulation Control With Oral Vitamin K as an Adjuvant to Warfarin Therapy (LOCK)
July 26, 2011 updated by: Ottawa Hospital Research Institute
A Phase III Pilot RCT (Randomized, Controlled Trial) to Assess the Effectiveness of Low Dose Vitamin K1 (200 Micrograms Per Day) on Improving Anticoagulation Control in Unstable Patients on Warfarin
The main objective of this study is to assess the effectiveness of low dose Vitamin K1 (200 micrograms per day) at improving anticoagulation control in unstable patients on warfarin.
This study will also aim to look at effectiveness in the context of genes known to influence warfarin metabolism, variability in the consumption of Vitamin K rich foods, and patient knowledge about warfarin anticoagulation -- factors which have been associated with anticoagulation control and which can influence the effectiveness of this intervention in clinical practice.
Study Overview
Status
Completed
Conditions
Intervention / Treatment
Detailed Description
A double-blinded placebo controlled pilot RCT assessing the effectiveness of daily supplementation with low dose Vitamin K1 (200 micrograms per day) against placebo at improving anticoagulation control.
Previous studies assessing the efficacy of this intervention have been small and further trials are required to evaluate the true effectiveness and safety profile.
Furthermore the impact of genetic polymorphisms, known to impact warfarin metabolism, on the effectiveness/safety of this intervention will also be assessed in this study.
Demographic and clinical variables as well as potential confounding variables such as variable dietary Vitamin K intake, concomitant interacting medications, and anticoagulation knowledge will be assessed in this study.
Given that this is a pilot study we will be looking at recruitment numbers and necessary parameter estimates to determine the number of patients available at our institution for the study.
Power analysis will be performed to evaluate the treatment effect size between the placebo and intervention groups.
Study Type
Interventional
Enrollment (Anticipated)
100
Phase
- Phase 3
Contacts and Locations
This section provides the contact details for those conducting the study, and information on where this study is being conducted.
Study Locations
-
-
Ontario
-
Ottawa, Ontario, Canada, K1Y4E9
- Ottawa Hospital Thrombosis Clinic
-
-
Participation Criteria
Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.
Eligibility Criteria
Ages Eligible for Study
16 years and older (Adult, Older Adult)
Accepts Healthy Volunteers
No
Genders Eligible for Study
All
Description
Inclusion Criteria:
- >= 18 years old
- Have been on warfarin anticoagulation for at least 9 months
- Have an INR target range of 2.0-3.0
- Have "unstable" anticoagulation control, defined as in the preceding 6 months having at least 3 INRs out of range (>= 3.2 or =<1.8) or at least 3 warfarin dose changes
- Have anticoagulation managed by the Ottawa Hospital Thrombosis Clinic
- Able to provide written, informed consent
Exclusion Criteria:
- Anticipated interruption or termination of warfarin anticoagulation in the next six months for a period of 1 week or greater
- Patient instability in the preceding six months suspected to be due to a) Interruption of warfarin therapy for a period of 1 week or more or b) Significant non-compliance (assessed from patient record)
- Possess a known allergy to Vitamin K or lactose based placebos
- Unable/Refusal to provide written, informed consent
Study Plan
This section provides details of the study plan, including how the study is designed and what the study is measuring.
How is the study designed?
Design Details
- Primary Purpose: Treatment
- Allocation: Randomized
- Interventional Model: Parallel Assignment
- Masking: Triple
Arms and Interventions
Participant Group / Arm |
Intervention / Treatment |
---|---|
Placebo Comparator: Placebo
|
Lactose-based placebo tablets (identical in appearance to the Vitamin K1 tablets) will be taken by patients randomized to the placebo arm.
Dosage is two tablets per day to be taken with warfarin for the 6 month study period.
|
Active Comparator: Vitamin K
|
Vitamin K1 tablets (100 micrograms per tablet) will be taken by patients randomized to the Vitamin K arm.
Dosage is two tablets per day (200 micrograms per day) to be taken with warfarin for the 6 month study period.
|
What is the study measuring?
Primary Outcome Measures
Outcome Measure |
Time Frame |
---|---|
Anticoagulation control -- Point estimates (and standard deviations) for the following variables: Percent time in therapeutic range, standard deviation of INRs, number of INRs outside of therapeutic range, and number of dose changes
Time Frame: At study initiation (for the six month pre-intervention period) and at study completion (after the six-month intervention period)
|
At study initiation (for the six month pre-intervention period) and at study completion (after the six-month intervention period)
|
Recruitment Numbers -- Number of patients deemed eligible, Number of patients solicited, Number of patients screened, Number of patients enrolled, and Number of enrolled patients lost to follow-up
Time Frame: Monthly
|
Monthly
|
Secondary Outcome Measures
Outcome Measure |
Time Frame |
---|---|
Bleeding Events -- Both major and minor as defined by the International Society on Thrombosis and Haemostasis (ISTH) criteria
Time Frame: Over 6 month study period
|
Over 6 month study period
|
Recurrent thrombosis
Time Frame: Over six month study period
|
Over six month study period
|
Collaborators and Investigators
This is where you will find people and organizations involved with this study.
Investigators
- Principal Investigator: Philip S Wells, MD, MSc, Ottawa Hospital, Ottawa Health Research Institute
Study record dates
These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.
Study Major Dates
Study Start
November 1, 2008
Primary Completion (Actual)
April 1, 2010
Study Completion (Actual)
April 1, 2010
Study Registration Dates
First Submitted
November 18, 2008
First Submitted That Met QC Criteria
November 19, 2008
First Posted (Estimate)
November 20, 2008
Study Record Updates
Last Update Posted (Estimate)
July 27, 2011
Last Update Submitted That Met QC Criteria
July 26, 2011
Last Verified
July 1, 2011
More Information
Terms related to this study
Keywords
Additional Relevant MeSH Terms
Other Study ID Numbers
- OHREB #2008555-01H
This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.
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