Randomized Comparison of Warfarin Dosing Quality Between the Hamilton Nomogram and a Commercial Computer System

Study Overview
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Brief Summary
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Randomized comparison of warfarin dosing quality between the Hamilton nomogram and a commercial computer system. Hypothesis: Mean TTR of patients managed with the commercial computer system is non-inferior to management with the validated Hamilton Nomogram.

Detailed Description
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Warfarin has a variable effect and many potential food and drug interactions. To have an optimal therapeutic effect the International Normalized Ratio (INR) needs to be maintained within the therapeutic target range. The time that a patient spends within the therapeutic target range is an intermediate quality indicator for patient outcomes and should be optimized. For this purpose, we use in our anticoagulation clinic the simple two-step Hamilton nomogram, which has been validated by Kim et al. who showed that the nomogram improved INR control for warfarin maintenance compared with expertise-based dosing in our anticoagulation clinic (see references). Computer systems are also known to outperform expertise-based dosing, but no direct comparison of a computer system with a simple nomogram has been assessed. In this single-center randomized controlled clinical trial we will compare the simple two-step Hamilton nomogram with the widely used computerized dosing management system DAWN AC regarding their effect on time in therapeutic range for patients on maintenance dosing with target range 2-3.

Official Title
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Randomized Comparison of Warfarin Dosing Quality Between the Hamilton Nomogram and a Commercial Computer System

Conditions
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Patients at Risk for Thrombosis

Intervention / Treatment
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* Device: DAWN AC
* Device: Hamilton Nomogram


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: On warfarin maintenance therapy INR target range 2-3 At least 3 historical INRs on maintenance therapy At least 1 historical INR in the last 3 months Exclusion Criteria: Participation in another study On multiple pill strengths

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: DAWN AC<br> | Device: DAWN AC<br>* computerized dosing management system for anticoagulation clinics<br>* Other names: DAWN AC, 4S Information Systems Ltd.;|
| Active Comparator: Hamilton Nomogram<br> | Device: Hamilton Nomogram<br>* simple nomogram for warfarin maintenance dosing<br>* Other names: Nomogram (algorithm);|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| TTR: The proportion of time a patient spends in the therapeutic INR range (2-3) |  | TTR calculated over the entire study period (6 months) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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anticoagulation, warfarin, computer systems, international normalized ratio, nomograms