Use of Phytonadione to Reduce International Normalized Ratio (INR) Variability in Patients on Long-term Warfarin Therapy
Background: Warfarin is used as an anti-coagulant in patients at risk of developing thrombosis. It has a narrow therapeutic index necessitating close monitoring of International Normalized Ratio (INR). According to a meta-analysis, patients were in therapeutic range only 63.6% of the time. This increases the risk of bleeding or thrombosis. Various retrospective and prospective studies have looked at supplementation with phytonadione in these patients to reduce the variability of INR showing an improvement in variability. Most of these studies have only been done in a small number of patients already on warfarin therapy. This study will focus on patients newly starting warfarin therapy.
Methods: This study is a prospective, randomized, controlled trial performed at James A. Haley Veterans' Hospital (JAHVA). Patients who meet criteria and sign informed consent will receive either phytonadione with warfarin or warfarin alone. Based on a power calculation for 80%, a total of 370 patients will be enrolled (185 participants in each arm). Participants will be randomized to either intervention or control. Intervention group participants will be prescribed their usual starting dose of warfarin along with 200 mcg phytonadione by mouth daily. Control group participants will be prescribed their usual starting dose of warfarin. Both groups will follow the usual standard of care. They will come in for a follow-up INR and warfarin dose titration at least once per week until therapeutic, and then as instructed up to every 6 weeks thereafter. Both groups will participate in anticoagulation clinic activities that constitute the current standard of care. Intervention will last for a total of 6 months for each participant once enrolled.
Hypothesis:Participants in the intervention group being supplemented with 200mcg of phytonadione will spend more total time with a therapeutic INR than participants in the control group.
|Study Design:||Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Open Label
Primary Purpose: Treatment
|Official Title:||Use of Phytonadione to Reduce INR Variability in Patients on Long-term Warfarin Therapy|
- The primary outcome of this study is to determine the length of time in therapeutic INR range for patients given phytonadione and warfarin compared to warfarin alone [ Time Frame: 6 months ]
- Secondary outcomes include the number of adverse events in the form of bleeding or thrombosis for both groups. [ Time Frame: 6 months ]
|Study Start Date:||September 2011|
|Study Completion Date:||November 2015|
|Primary Completion Date:||November 2015 (Final data collection date for primary outcome measure)|
Active Comparator: Control group
The control group only receiving warfarin therapy.
Drug: none-control group
none. Pts will receive normal doses of warfarin and standard of care follow-up.
Other Name: Coumadin
Patients receiving 200mcg of phytonadione.
Dietary Supplement: phytonadione
Phytonadione 200mcg PO daily for 6 months + normal dose of warfarin and standard of care treatment
Please refer to this study by its ClinicalTrials.gov identifier: NCT01474460
|United States, Florida|
|James A. Haley VA Hospital|
|Tampa, Florida, United States, 33612|
|Principal Investigator:||To-Nga Huynh, PharmD||James A. Haley VA Hospital|