Brian F. Gage, MD, MSc
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Gage BF. Randomized Trial of Warfarin Nomograms. Ann Intern Med. 2004;140:489. doi: 10.7326/0003-4819-140-6-200403160-00025
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Published: Ann Intern Med. 2004;140(6):489.
TO THE EDITOR:
In their randomized, controlled trial, Kovacs and colleagues (1) showed that initiating warfarin therapy by prescribing 10 mg on days 1 and 2 reduced the time required to achieve a therapeutic INR, compared with 5-mg doses. Their findings parallel the results of a similar trial (2) and show that starting with a higher dose of warfarin elevates the INR more rapidly.
However, the risks of using this dosing scheme probably outweigh the benefits, particularly among the elderly. The primary benefit, achieving a therapeutic INR 1.4 days earlier, is small. In contrast, hemorrhagic complications caused by excessive anticoagulation (3) can have permanent sequelae. Others have reported that the use of an initial 10-mg dose can lead to overdose in elderly patients (2, 4), cause bleeding (3), and rapidly deplete levels of protein C (5). Given these concerns, it would be reassuring if the authors provided the rates of adverse events (including minor bleeding and use of vitamin K) during the first 2 to 3 weeks of treatment and also showed the distribution of peak INR values in the 2 cohorts, particularly in persons older than 60 years of age.
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Print ISSN: 0003-4819 | Online ISSN: 1539-3704
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