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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.
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.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Vitamin K | Active Comparator |
| |
| Placebo | Placebo Comparator |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Vitamin K1 (Phytonadione) | Dietary Supplement | 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. |
| Measure | Description | 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 | 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 | Monthly |
| Measure | Description | Time Frame |
|---|---|---|
| Bleeding Events -- Both major and minor as defined by the International Society on Thrombosis and Haemostasis (ISTH) criteria | Over 6 month study period | |
| Recurrent thrombosis | Over six month study period |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Philip S Wells, MD, MSc | Ottawa Hospital, Ottawa Health Research Institute | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Ottawa Hospital Thrombosis Clinic | Ottawa | Ontario | K1Y4E9 | Canada |
| Type | Date | Date Unknown |
|---|---|---|
| Release | Jun 11, 2018 | |
| Reset | Dec 21, 2018 | |
| Release | Mar 2, 2021 | |
| Reset | Mar 25, 2021 | |
| Release | Oct 1, 2021 | |
| Reset | Oct 27, 2021 |
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| Release Date | Unrelease Date | Unrelease Date Unknown | Reset Date | MCP Release Number |
|---|---|---|---|---|
| Jun 11, 2018 | Dec 21, 2018 | |||
| Mar 2, 2021 |
| ID | Term |
|---|---|
| D013927 | Thrombosis |
| ID | Term |
|---|---|
| D016769 | Embolism and Thrombosis |
| D014652 | Vascular Diseases |
| D002318 | Cardiovascular Diseases |
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| ID | Term |
|---|---|
| D010837 | Vitamin K 1 |
| ID | Term |
|---|---|
| D014812 | Vitamin K |
| D009285 | Naphthoquinones |
| D009281 | Naphthalenes |
| D011084 | Polycyclic Aromatic Hydrocarbons |
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| Placebo | Dietary Supplement | 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. |
|
| Mar 25, 2021 |
| Oct 1, 2021 | Oct 27, 2021 |
| D006841 |
| Hydrocarbons, Aromatic |
| D006844 | Hydrocarbons, Cyclic |
| D006838 | Hydrocarbons |
| D009930 | Organic Chemicals |
| D010836 | Phytol |
| D004224 | Diterpenes |
| D013729 | Terpenes |
| D011809 | Quinones |
| D011083 | Polycyclic Compounds |