Changes in International Normalized Ratios After Plasma Transfusion of Varying Doses in Unique Clinical Environments.

Background: Plasma transfusion is commonly performed for the correction of abnormal coagulation screening tests. The goal of this investigation was to assess the relationship between the dose of plasma administered and changes in coagulation test results in a large and diverse cohort of patients with varying levels of coagulation abnormalities and comorbid disease and in a variety of clinical settings.

Methods: In this single-center historical cohort study, all plasma transfusion episodes in adult patients with abnormal coagulation screening tests were extracted between 2011 and 2015. The primary outcome was the proportion of patients attaining normal posttransfusion international normalized ratio (INR ≤ 1.1) with secondary outcomes including the proportion of patients attaining partial normalization of INR (INR ≤ 1.5) or at least 50% normalization in pretransfusion values with respect to an INR of 1.1.

Results: In total, 6779 unique patients received plasma with a median (quartiles) pretransfusion INR of 1.9 (1.6-2.5) and a median transfusion volume of 2 (2-3) units. The majority (85%) of transfusions occurred perioperatively, with 20% of transfusions administered prophylactically before a procedure. The median decrease in INR was 0.4 (0.2-0.8). Complete INR normalization was obtained in 12%. Reductions in INR were modest with pretransfusion INR values <3. Patients receiving ≥3 units of plasma were more likely to achieve at least 50% normalization in INR than those receiving ≤2 units (68% vs 60%; P < .001).

Conclusions: Changes in INR after plasma transfusion were modest at typically used clinical doses, particularly in those with less severely deranged baseline coagulation screening tests. Further studies are necessary to assess the relationships between plasma-mediated changes in INR and clinical outcomes.