assessing anticoagulation control with vitamin K antagonists

Last reviewed 01/2018

Assessing anticoagulation control with vitamin K antagonists

  • calculate the person's time in therapeutic range (TTR) at each visit. When calculating TTR:
    • use a validated method of measurement such as the Rosendaal method for computer-assisted dosing or proportion of tests in range for manual dosing
    • exclude measurements taken during the first 6 weeks of treatment
    • calculate TTR over a maintenance period of at least 6 months

Reassess anticoagulation for a person with poor anticoagulation control shown by any of the following:

  • 2 INR values higher than 5 or 1 INR value higher than 8 within the past 6 months

  • 2 INR values less than 1.5 within the past 6 months

  • TTR less than 65%

Reference:

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