This site became the new on June 19th. Learn more.
Show more Menu IMPORTANT: Listing of a study on this site does not reflect endorsement by the National Institutes of Health. Talk with a trusted healthcare professional before volunteering for a study. Read more... Menu IMPORTANT: Talk with a trusted healthcare professional before volunteering for a study. Read more... Menu
Give us feedback

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

This study has been completed.
Information provided by:
Population Health Research Institute Identifier:
First received: December 1, 2009
Last updated: July 19, 2011
Last verified: December 2009

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.

Condition Intervention Phase
Patients at Risk for Thrombosis Device: DAWN AC Device: Hamilton Nomogram Phase 3

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single (Participant)
Primary Purpose: Treatment
Official Title: Randomized Comparison of Warfarin Dosing Quality Between the Hamilton Nomogram and a Commercial Computer System

Resource links provided by NLM:

Further study details as provided by Population Health Research Institute:

Primary Outcome Measures:
  • TTR: The proportion of time a patient spends in the therapeutic INR range (2-3) [ Time Frame: TTR calculated over the entire study period (6 months) ]

Enrollment: 1298
Study Start Date: November 2009
Study Completion Date: August 2010
Primary Completion Date: August 2010 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: DAWN AC Device: DAWN AC
computerized dosing management system for anticoagulation clinics
Other Name: DAWN AC, 4S Information Systems Ltd.
Active Comparator: Hamilton Nomogram Device: Hamilton Nomogram
simple nomogram for warfarin maintenance dosing
Other Name: Nomogram (algorithm)

Detailed Description:
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.

Ages Eligible for Study:   18 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

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
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT01024452

Canada, Ontario
Hamilton General Hospital
Hamilton, Ontario, Canada, L8L 2X2
Sponsors and Collaborators
Population Health Research Institute
Principal Investigator: Stuart Connolly, MD Director, Division of Cardiology
  More Information

Responsible Party: Dr. S. Connolly, Population Health Research Institute Identifier: NCT01024452     History of Changes
Other Study ID Numbers: 09-283
Study First Received: December 1, 2009
Last Updated: July 19, 2011

Keywords provided by Population Health Research Institute:
computer systems
international normalized ratio

Additional relevant MeSH terms:
Embolism and Thrombosis
Vascular Diseases
Cardiovascular Diseases
Anticoagulants processed this record on September 21, 2017