Abstract Number: PB0320
Meeting: ISTH 2021 Congress
Background: Fresh frozen plasma (FFP) is the most widely-used blood component to correct prolonged International Normalized Ratio (INR). However, There is little knowledge about factors related to normalized INR and about the appropriate amount of FFP to correct prolonged INR.
Aims: To develop a formula to calculate the appropriate amount of FFP for correction of prolonged INR and analyze factors related to normalized INR.
Methods: Retrospective chart-review study includes 144 patients, aged > 18 years, who had prolonged INR (>1.5) and were transfused with FFP with INR value after transfusion between September 5, 2019 and September 18, 2020. Ninety-six and 48 patients were in warfarin and non-warfarin groups, respectively. The following parameters were collected and analyzed: principal diagnosis, comorbidities, pre-transfusion INR (PreINR), post-transfusion INR (PostINR), ∆INR (PreINR–PostINR), vitamin K given, amount of FFP, and date and time when blood samples were collected.
Results: The median (range) PreINR was 2.67 (1.50 – 14.64) and median (range) ∆INR was 0.87 (-0.09 – 12.81). The mean (SD) amount of FFP was 2.2+0.6 units. The median (range) time from FFP administration to PostINR testing were 4 hours (0-19). The median (range) time between PreINR and PostINR testings were 10 hours (3-33). Vitamin K was given in 88 patients (oral 5, intravenous 83). The formula ∆INR after FFP 2 units = (0.91 x PreINR) – 1.38 (R2= 0.964 between predicted INR and actual improvement INR; P < 0.001). The factors correlated with normalized PostINR (INR <1.5) were lower PreINR level (adjusted odds ratio [aOR] = 0.64, P=0.017), intravenous vitamin K (aOR = 1.74, P=0.025), and longer duration between PreINR and PostINR testings (aOR = 1.30, P=0.001).
|Subgroup||N||Formula of ∆INR (A = PreINR)||R2||P-value|
|FFP 2 units||126||0.908A – 1.375||0.964||<0.001|
|Warfarin user||96||0.920A – 1.444||0.962||<0.001|
|Warfarin user and FFP 2 units||84||0.921A – 1.455||0.962||<0.001|
|Non-warfarin user||48||0.526A – 0.586||0.589||<0.001|
|Non-warfarin user and FFP 2 units||42||0.573A – 0.675||0.649||<0.001|
|Warfarin user + FFP 2 units + Vit.K IV >= 5 mg||48||0.941A – 1.404||0.974||<0.001|
|Warfarin user + FFP 2 units + Vit.K IV < 5 mg or oral Vit.K or without Vit.K||36||0.780A – 1.168||0.936||<0.001|
|Non-warfarin user + FFP 2 units + Vit.K IV >= 5 mg||23||1.024A – 1.496||0.718||<0.001|
|Non-warfarin user + FFP 2 units + Vit.K IV < 5mg or oral Vit.K or without Vit.K||19||0.476A – 0.521||0.786||<0.001|
Conclusions: This formula may be used to predict INR after 2-unit FFP transfusion. Factors correlated with normalized INR after transfusion were lower pre-transfusion INR, intravenous vitamin K, and longer duration between pre- and post-transfusion INR measurement.
To cite this abstract in AMA style:Pinitsubsin L, Chinthammitr Y. Calculation of Fresh Frozen Plasma Amount to Correct Prolonged International Normalized Ratio [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/calculation-of-fresh-frozen-plasma-amount-to-correct-prolonged-international-normalized-ratio/. Accessed December 8, 2021.
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