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HOME MONITORING OF THE PROTHROMBIN TIME.

One deterrent to chronic warfarin therapy is the need to frequently monitor prothrombin time (PT) to ensure effective anticoagulation and minimize bleeding complications. These Canadian researchers tested the accuracy of home PT monitoring by long-term warfarin users, using a portable monitor that measures PT from a drop of blood drawn from the fingertip.

Forty patients taking warfarin for 6 to 24 months monitored their PT at home. At designated intervals, the home test was followed within 4 hours by a laboratory measurement. The mean agreement between the two tests was 83 percent, when agreement was defined as both measurements falling within or outside the target therapeutic range or within 0.4 international normalized ratio (INR) units of each other. Agreement increased to 96 percent when the upper and lower limits of the target range were extended by 0.4 INR units. Only one patient had widely discrepant results, which were due to flawed technique in use of the home monitor. Nearly all patients preferred home monitoring over traveling to an outpatient laboratory.

Comment: The authors believe that home PT monitoring is sufficiently accurate to allow its use in selected cases. For patients requiring lifelong anticoagulation, the convenience of home monitoring might well offset its expense ($600 for the machine, plus $4 per test).

— ASB

Published in Journal Watch General Medicine July 13, 1993

Citation(s):

Anderson DR et al. Evaluation of a portable prothrombin time monitor for home use by patients who require long-term oral anticoagulant therapy. Arch Intern Med 1993 Jun 28 153 1441-1447.

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