Abstract Number: PB0568
Meeting: ISTH 2020 Congress
Background: Warfarin dose initiation is often a trial and error challenging process which is often time consuming. Dose prediction nomograms, pharmacokinetic formulas and computer softwares have all been tried to facilitate and speed the process achieving a stable steady state INR. In a recent study (JTH 2010; 8: 90) a simple one week warfarin loading nomogram was used successfully for such patients.
Aims: To investigate the validity on the warfarin loading model in a cohort of warfarin first time users.
Methods: Consecutive patients starting warfarin treatment were routinely dosed with the use of the nomogram at our center starting from 2015. All patients were followed at our outpatient clinic and their steady state warfarin maintenance dose (dose resulting in 2 successive INRs in the desired therapeutic range) was compared to the predicted dose. We compared the difference between predicted to actual doses to the null hypothesis of zero difference and used reliability testing to study the correlation between the predicted and actual daily doses.
Results: Thirty five patients (23 females, median age 47.5 IQR 21.5) were studied. Warfarin treatment indication was mainly venous thromboembolism (31/35) except for four patients treated for atrial fibrillation or arterial thrombosis. Steady state (median ± IQR) predicted daily warfarin dose was 5.51±2.28 mg compared to 5.53±1.97 mg actual daily dose and not statistically different (P=0.98). The median difference between predicted and actual warfarin steady state dose was 0.015 mg (IQR 0.61) and was not different from zero (P=0.332). The intra-class correlation coefficient was 0.970 (0.938-0.985).
Conclusions: The warfarin steady state dose prediction tool was able to precisely predict warfarin steady state maintenance dose with good accuracy within a week after starting warfarin treatment and may be a useful tool to shorten the time period to reach safe warfarin anticoagulation.
[Predicted vs. actual daily steady state warfarin doses]
To cite this abstract in AMA style:
Lubetsky A, Cohen O, Kenet G. Validation of a Warfarin Dose Prediction Model: A Single Center Retrospective Study [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/validation-of-a-warfarin-dose-prediction-model-a-single-center-retrospective-study/. Accessed April 18, 2024.« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/validation-of-a-warfarin-dose-prediction-model-a-single-center-retrospective-study/