Adding up the evidence: Trigger for prophylactic plasma transfusion.

Sir,

Fresh frozen plasma (FFP) continues to be a globally accepted hemostatic agent despite a weak evidence base. Conventionally, laboratories report international normalized ratio (INR) which helps physicians to base their clinical decisions of transfusing plasma above a certain threshold typically 1.5 times the control. However, several factors such as laboratory reagents and biological factors are associated with spuriously prolonged values not associated with a bleeding risk.[1] Therefore, the problems of relating the standard in vitro tests to in vivo hemostasis continue to exist. One of the common indications where plasma is requested is to normalize an elevated INR before a planned surgery or invasive procedure. The assumptions in this situation are that the elevated INR correlates with a risk for bleeding and that plasma transfusion will normalize the INR and reduce this risk.[2] The current recommendations are based largely on expert opinion, and a precautionary approach to the correction of abnormal laboratory tests is often used.[3]

We conducted a utilization review for FFP between December 2012 and October 2013. Patients fulfilling inclusion criteria were randomly assigned to receive a single dose of 10–15 mL/kg plasma. In 2082 episodes, 4991 units of plasma were utilized in 998 patients at median mL/kg (Q1 to Q3; Range) dosage of 10.1 mL/kg (5.8–13.4; 1.2–48.5) per patient. We observed that the mean reduction in INR was statistically significant (P < 0.001) at higher pretransfusion INR (value >3.0) when compared to the lower pretransfusion INR (value <1.5).

Another interesting observation made was that the values of mean change in INR per unit of plasma adjusted according to the body weight gradually increased against the rising value of pretransfusion INR. There was a sudden increase in the values of mean change in INR per unit of plasma at the pretransfusion INR value of 1.7 [Figure 1], and this change was statistically significant when compared to the conventional pretransfusion INR value of 1.5 (P < 0.001).

Figure 1

Evidence-based use of higher pretransfusion international normalized ratio as a threshold for plasma transfusions

Abdel-Wahab et al. had shown that those with higher INRs (1.5–1.85) were more likely to correct their coagulation parameters in comparison to those with lower INRs (1.1–1.5).[4] Holland and Brooks also based on their data predicted that around 50% of adult and pediatric patients had a significant change at an INR of 1.7 when expressed per plasma transfusion and that was minimally effective in correcting mild elevations in INR value (<1.7). Furthermore, at the conventional cutoff of 1.5, only about 38% of transfusions were predicted to cause a significant change.[5]

Similar to these observations, our study also shows that an INR value of 1.7 should be considered as the threshold trigger for initiating prophylactic plasma transfusion rather than the conventional INR value of 1.5.

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Conflicts of interest

There are no conflicts of interest.