Thromb Haemost 2012; 108(06): 1228-1235
DOI: 10.1160/TH12-06-0433
New Technologies, Diagnostic Tools and Drugs
Schattauer GmbH

Randomised comparison of a simple warfarin dosing algorithm versus a computerised anticoagulation management system for control of warfarin maintenance therapy

Robby Nieuwlaat
1   Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada
2   Department of Clinical Epidemiology &Biostatistics, McMaster University, Hamilton, Ontario, Canada
,
Lowiek M. Hubers
1   Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada
,
Alex C. Spyropoulos
3   Division of Hematology and Oncology, Department of Medicine, University of Rochester Medical Center, Rochester, New York, USA
,
John W. Eikelboom
1   Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada
4   Department of Medicine, McMaster University, Hamilton, Ontario, Canada
,
Benjamin J. Connolly
1   Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada
,
Harriette G. C. Van Spall
1   Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada
4   Department of Medicine, McMaster University, Hamilton, Ontario, Canada
,
Karleen M. Schulze
1   Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada
,
Spencer M. Cuddy
1   Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada
,
Alexander C. Stehouwer
1   Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada
,
Sam Schulman
4   Department of Medicine, McMaster University, Hamilton, Ontario, Canada
,
Stuart J. Connolly
1   Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada
4   Department of Medicine, McMaster University, Hamilton, Ontario, Canada
› Author Affiliations
Further Information

Publication History

Received: 25 June 2012

Accepted after major revision: 31 August 2012

Publication Date:
30 November 2017 (online)

Summary

Excellent control of the international normalised ratio (INR) is associated with improved clinical outcomes in patients receiving warfarin, and can be achieved by anticoagulation clinics but is difficult in general practice. Anticoagulation clinics have often used validated commercial computer systems to manage the INR, but these are not usually available to general practitioners. It was the objective of this study to perform a randomised trial of a simple one-step warfarin dosing algorithm against a widely used computerised dosing system. During the period of introduction of a commercial computerised warfarin dosing system (DAWN AC) to an anticoagulation clinic, patients were randomised to have warfarin dose adjustment done according to recommendations of the existing warfarin dosing algorithm or to those of the computerised system. The study tested if the computerised system was non-inferior to the existing algorithm for the primary outcome of time in therapeutic INR range of 2.0–3.0 (TTR), with a one-sided non-inferiority margin of 4.5%. There were 541 patients randomised to commercial computerised system and 527 to the algorithm. Median follow-up was 159 days. A dose recommendation was provided and followed in 91% of occasions for the computerised system and in 90% for the algorithm (p=0.03). The mean TTR was 71.0% (standard deviation [SD] 23.2) for the computerised system and 71.9% (SD 22.9) for the algorithm (difference 0.9% [95% confidence interval: –1.4% to 4.1%];p-value for noninferiority=0.002;p-value for superiority=0.34). In conclusion, similar maintenance control of the INR was achieved with a simple one-step dosing algorithm and a commercial computerised management system.

 
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