Low Dose Supplementation to Improve Anticoagulation Control With Oral Vitamin K as an Adjuvant to Warfarin Therapy

NCT00794755 | Completed Phase 3 DMC

• 1 other identifier: OHREB #2008555-01H
• Study Type: interventional
• Target: 100
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Coagulation

Keywords

Vitamin K; Vitamin K1 (Phytonadione); Unstable INR; VTE or Thrombosis; Warfarin; Anticoagulation Control; Patients on warfarin with unstable anticoagulation control

Outcome Measures

Primary Outcomes (2)

• 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

Secondary Outcomes (2)

• 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

Study Arms (2)

Vitamin K

ACTIVE COMPARATOR

Dietary Supplement: Vitamin K1 (Phytonadione)

Placebo

PLACEBO COMPARATOR

Dietary Supplement: Placebo

Interventions

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.

Vitamin K

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.

Placebo

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• \>= 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Ottawa Hospital Research Institute: lead

Study Sites (1)

Ottawa Hospital Thrombosis Clinic

Ottawa, Ontario, K1Y4E9, Canada

Location

MeSH Terms

Conditions

Thrombosis

Interventions

Vitamin K 1

Condition Hierarchy (Ancestors)

Embolism and Thrombosis; Vascular Diseases; Cardiovascular Diseases

Intervention Hierarchy (Ancestors)

Vitamin K; Naphthoquinones; Naphthalenes; Polycyclic Aromatic Hydrocarbons; Hydrocarbons, Aromatic; Hydrocarbons, Cyclic; Hydrocarbons; Organic Chemicals; Phytol; Diterpenes; Terpenes; Quinones; Polycyclic Compounds

Study Officials

• Philip S Wells, MD, MSc

  Ottawa Hospital, Ottawa Health Research Institute

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER

Study Record Dates

• First Submitted: November 18, 2008
• First Posted: November 20, 2008
• Study Start: November 1, 2008
• Primary Completion: April 1, 2010
• Study Completion: April 1, 2010
• Last Updated: July 27, 2011

Record last verified: 2011-07

Locations

CA (1)