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Published on: August 4, 2018
Warfarin induced coagulopathy in children: assessment of a conservative approach
M E Bauman1, K Black, M L Bauman
1Stollery Children's Hospital, University of Alberta, Edmonton, Alberta, Canada.
Insights
Withholding warfarin for children with elevated international normalised ratio (INR) above 5 is safe and effective. This approach avoids vitamin K and prevents bleeding events in pediatric patients on warfarin therapy.
Area of Science:
- Pediatric Thrombosis and Hemostasis
- Pharmacology and Therapeutics
Background:
- Warfarin is frequently used for thromboprophylaxis in children, requiring careful management due to its narrow therapeutic window.
- Elevated international normalised ratio (INR) levels, especially above 5.0, increase bleeding risk exponentially in pediatric patients.
- Current practice for adults with INRs between 5 and 9 involves withholding warfarin, a strategy whose safety in children is less understood.
Purpose of the Study:
- To evaluate the safety and efficacy of a conservative management strategy for elevated INRs (≥5) in children receiving warfarin.
- To assess the impact of withholding warfarin without vitamin K on INR levels and clinical outcomes in pediatric patients.
Main Methods:
- A retrospective study involving 89 children (aged 1-16 years) on warfarin therapy.
- Analysis of 2353 INR results, focusing on 26 instances where INR was ≥5.
- Warfarin was withheld for INRs ≥5, with repeat INR measurement the following day, excluding vitamin K administration.
Main Results:
- Twenty-six children experienced INRs ≥5 (mean 5.9), representing 5% of all INRs performed.
- Withholding warfarin led to a mean next-day INR of 3.3, with 89% of these INRs falling below 5.
- No overt bleeding or thrombotic events occurred within one month following the elevated INR.
- The time in therapeutic range for children with prior INRs ≥5 was 68%.
Conclusions:
- Withholding warfarin alone is a safe and effective strategy for managing non-bleeding international normalised ratio (INR) levels between 5 and 8 in children.
- This conservative approach can help maintain therapeutic anticoagulation while minimizing bleeding risks in pediatric patients.
Background:
Increasing numbers of children are being administered warfarin therapy as thromboprophylaxis. Warfarin has a narrow therapeutic window with a target international normalised ratio (INR) of 2-3.5, called the therapeutic range. The length of time a patient's INR remains within the therapeutic range is calculated as 'time in the therapeutic range'. Risk for haemorrhage in children receiving warfarin is 0.5%/patient-year and minor bleeding 2.3%/patient-year, which increases exponentially for INRs >5.0. Practice among non-bleeding adults with INRs ≥5 and ≤9 is to withhold warfarin and allow the INR to return to the therapeutic range. Faster warfarin clearance is correlated with younger age.
Methods And Results:
The study objective was to determine the safety and effectiveness of a conservative approach for management of INRs >5 in children receiving warfarin. Children receiving warfarin with INRs ≥5 had warfarin withheld followed by a next day INR without vitamin K administration. Eighty-nine children (1-16 years) participated in the study with 2353 INRs performed. Twenty-six children had INRs ≥5, 5% of the total performed, with a mean INR of 5.9. The next day repeat mean INR after withholding one dose of warfarin was 3.3 (range 1.2-6.8) with 89% of INRs falling below 5. There were no overt bleeds or symptomatic thrombotic events in the month following the INR >5. Time in the therapeutic range for children with INRs ≥5 was 68%.
Conclusions:
Withholding warfarin alone for management of non-bleeding INRs ≥5 and ≤8 appears to be safe and effective.
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