Clinical trial NCT01124058: Evaluation of Maintenance Dosing vs Loading Dosing Upon Restarting Warfarin Therapy: A Prospective Randomized Trial
Official title: Evaluation of Maintenance Dosing vs Loading Dosing Upon Restarting Warfarin Therapy: A Prospective Randomized Trial.
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: PHASE1
Conditions: Anticoagulation
Keywords: restarting warfarin
time to therapeutic INR
Lead sponsor: University of Alberta
Sponsor class: OTHER
First posted: 2010-05-14
Enrollment: 39
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: TREATMENT

Brief summary: A prospective, randomized trial to compare the time taken to achieve a therapeutic INR upon re-starting warfarin at a "loading" dose (namely 1.5 times the "maintenance" dose for 3 days) compared to the known "maintenance" dose.

Detailed description: Patients will be identified via the University of Alberta Hospital Anticoagulation Management Service. Following the receipt of written, informed consent, patients will be randomized to re-start warfarin at their "maintenance" dose or at a "loading" dose (1.5 times the maintenance dose for 3 days, then resumption of warfarin dosing as per the maintenance dose). Randomization will be performed on-line through the EPICORE Centre.

Assuming Day 1 is the day warfarin is re-started, patients will have INRs done on day 3 and at least every 2 days thereafter until a therapeutic INR is obtained. In addition, protein C, protein S and factor II levels will be obtained while the patient is on stable maintenance dosing of warfarin (i.e., prior to holding warfarin for the procedure), 7 days after re-starting warfarin, and 14 days after re-starting warfarin. Complete blood counts (CBCs) will be done with each INR if the patient is taking a low molecular weight heparin (LMWH). Patients will have their anticoagulant therapy managed by the AMS for 6 weeks and will receive a telephone follow-up by the AMS at 90 days to determine if any bleeding or clotting complications occurred.

Eligibility criteria: Inclusion Criteria:

* Have 'stable warfarin maintenance dosing' (defined as last 2 INRs within therapeutic range with weekly warfarin dosing not being changed any more than 10%)
* Have an INR indicative of not taking any warfarin (INR \<1.4) or confirmation of the patient not taking any warfarin in the past 4 days
* Provide written, informed consent

Primary outcomes:
measure: re-starting warfarin "loading" dose vs "maintenance" dose
timeFrame: INR drawn 3 days post-reinitiation and then every 2 days until therapeutic
Secondary outcomes:
measure: Compare % of time within, above and below the target INR range
timeFrame: days
measure: Compare bleeding/clotting complications between two groups
timeFrame: 30 days, 90 days
measure: Compare the levels of protein C, protein S, and factor II between 2 groups.
timeFrame: week
Other outcomes:
Locations:
city: Edmonton
country: Canada
facility: Univeristy of Alberta
state: Alberta
Study officials:
affiliation: Univeristy of Alberta
name: Tammy J Bungard, BSP, PharmD
role: PRINCIPAL_INVESTIGATOR
affiliation: University of Alberta
name: Bruce Ritchie, MD, FRCPC
role: PRINCIPAL_INVESTIGATOR
References: