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Semin Vasc Med 2003; 03(3): 255-260
DOI: 10.1055/s-2003-44461
DOI: 10.1055/s-2003-44461
Oral Anticoagulant Initiation: Rationale for the Use of Warfarin Dosing Nomograms
Further Information
Publication History
Publication Date:
21 November 2003 (online)
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ABSTRACT
Oral anticoagulants prevent thrombosis however they are associated with bleeding. The risk of both bleeding and thrombosis is increased when the International Normalized Ratio (INR) is outside the desired therapeutic range. Hence, oral anticoagulants should be administered with the intention of maximizing the “time within the therapeutic range.” The frequency of INR values outside this range can be decreased by (1) warfarin initiation algorithms that guide initial therapy and (2) use of computerized systems to guide chronic warfarin therapy. This article reviews these techniques.
KEYWORDS
Warfarin initiation - dosing algorithms - computerized dosing - International Normalized Ratio
REFERENCES
- 1 O'Reilly R A, Aggeler P M. Studies on coumarin anticoagulant drugs. Initiation of warfarin without a loading dose. Circulation . 1968; 38 169-177
- 2 Kovacs M, Cruickshank M, Wells P S. et al . Randomized assessment of a warfarin nomogram for initial oral anticoagulation after venous thromboembolic disease. Haemostasis . 1999; 28 62-68
- 3 Ansell J, Hirsh J, Dalen J. et al . Managing oral anticoagulant therapy. Chest . 2001; 119 22S-38S
- 4 Hirsh J, Dalen J, Anderson D R. et al . Oral anticoagulants: mechanism of action, clinical effectiveness, and optimal therapeutic range. Chest . 2001; 119 8S-21S
- 5 Harrison L, Johnston M, Massicotte M P, Crowther M, Moffat K, Hirsh J. Comparison of 5-mg and 10-mg loading doses in initiation of warfarin therapy. Ann Intern Med . 1997; 126 133-136
- 6 Crowther M A, Ginsberg J, Kearon C. et al . A randomized trial comparing 5 mg and 10 mg warfarin loading doses. Arch Intern Med . 1999; 159 46-48
- 7 Ageno W, Turpie A G. Exaggerated initial response to warfarin following heart valve replacement. Am J Cardiol . 1999; 84 905-908
- 8 Gedge J, Orme S, Hampton K K, Channer K S, Hendra T J. A comparison of a low-dose warfarin induction regimen with the modified Fennerty regimen in elderly inpatients. Age Ageing . 2000; 29 31-34
- 9 Kovacs M J, Rodger M, Anderson D R. et al . Comparison of 10-mg and 5-mg warfarin initiation nomograms together with low-molecular-weight heparin for outpatient treatment of acute venous thromboembolism. A randomized, double-blind, controlled trial. Ann Intern Med . 2003; 138 714-719
- 10 Albers G W. Atrial fibrillation and stroke. Three new studies, three remaining questions. Arch Intern Med . 1994; 154 1443-1448
- 11 Aspect Research Group. Effect of long-term oral anticoagulant treatment on mortality and cardiovascular morbidity after myocardial infarction. Anticoagulants in the Secondary Prevention of Events in Coronary Thrombosis (ASPECT) Research Group. Lancet . 1994; 343 499-503
- 12 Hylek E M, Singer D E. Risk factors for intracranial hemorrhage in outpatients taking warfarin. Ann Intern Med . 1994; 120 897-902
- 13 Cannegieter S C, Rosendaal F R, Wintzen A R, van der Meer J F, Vandenbroucke J P, Briet E. Optimal oral anticoagulant therapy in patients with mechanical heart valves. N Engl J Med . 1995; 333 11-17
- 14 SPIRIT Study Group. A randomized trial of anticoagulants versus aspirin after cerebral ischemia of presumed arterial origin. The Stroke Prevention in Reversible Ischemia Trial (SPIRIT) Study Group. Ann Neurol . 1997; 42 857-865
- 15 Adjusted-dose warfarin versus low-intensity, fixed-dose warfarin plus aspirin for high-risk patients with atrial fibrillation: Stroke Prevention in Atrial Fibrillation III randomized trial. Lancet . 1996; 348 633-638
- 16 Wilson R, James A H. Computer assisted management of warfarin treatment. Br Med J . 1984; 289 422-424
- 17 Wyld P J, West D, Wilson T H. Computer dosing in anticoagulant clinics-the way forward?. Clin Lab Haematol . 1988; 10 235-236
- 18 Ryan P J, Gilbert M, Rose P E. Computer control of anticoagulant dose for therapeutic management. Br Med J . 1989; 299 1207-1209
- 19 Poller L, Wright D, Rowlands M. Prospective comparative study of computer programs used for management of warfarin. J Clin Pathol . 1993; 46 299-303
- 20 Ageno W, Turpie A G. A randomized comparison of a computer-based dosing program with a manual system to monitor oral anticoagulant therapy. Thromb Res . 1998; 91 237-240
- 21 Poller L, Shiach C R, MacCallum P K. et al . Multicentre randomised study of computerised anticoagulant dosage. European Concerted Action on Anticoagulation. Lancet . 1998; 352 1505-1509
- 22 Cromheecke M E, Levi M, Colly L P. et al . Oral anticoagulation self-management and management by a specialist anticoagulation clinic: a randomised cross-over comparison. Lancet . 2000; 356 97-102