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N.H. Saadah et al.
Netherlands.17 Within our analysis, the mean number of concurrently transfused RBC units was generally similar to or lower for SD plasma, transfused after 2014, than for FFP, transfused before 2016 (Figure 3). While we cannot separate the effects of plasma efficiency from those of this trend, our data suggest no differences in effectiveness of stoppage of bleeding between the two plasma types, despite a one third reduction of plasma volume being transfused following the switch to SD plasma.
The results of our transfusion reaction risk analysis, showing a lower incidence of allergic reactions, both ana- phylactic and ‘other’, for SD plasma as compared to FFP, are in line with those of several other studies in which SD plasma was consistently found to lead to fewer transfu- sion reactions in general.6–14 While transfusion reaction reporting practices likely changed during the seven years of data collection, the number of transfusion reactions reported to the National Haemovigilance Office has remained fairly constant across all categories in the last five years of FFP use (data not shown). This suggests the reporting procedures in use have reached steady-state, meaning a low risk of bias in our comparison due to dif- ferences in reporting processes between the periods in which two plasma products were used.
Given the rarity with which they are ascribed to plasma transfusion, our study did not observe enough TACO or TRALI cases to make meaningful conclusions with regards to their relative risks following FFP versus SD plasma transfusion, despite other studies noting a decreased inci- dence of TRALI with SD plasma.18 Of note, thus, is the TRALI case associated with transfusion of SD plasma in 2016. The patient, a pediatric stem-cell transplant recipi- ent, was already at an increased risk for respiratory trans- fusion reactions and had received transfusions of RBC and platelets, in addition to plasma.19 As a debatable case, this was further evaluated by an expert panel which agreed TRALI was a possibility but could not rule out TACO. As such, it was recorded in the TRIP database as a TRALI with a low imputability of ‘possible.’
Relevance and future research
Our study shows that in the Netherlands, reducing the size of plasma units by one third resulted in no change in the number of transfused plasma units. This suggests cli- nicians continued to transfuse the same number of plasma units, despite the decrease in volume, resulting in a reduc- tion of around one third in the country’s total transfused plasma volume. Given the SD process is not reported to increase product efficiency, the fact that the number of transfused RBC units did not concurrently increase at a population level serves as a suggestion, though not the first,20 that the clinical evidence base for the volume ratio of plasma to RBC transfused to stop bleeding needs re- evaluation. A logical next step would be an observational study exploring mortality in matched patients receiving different plasma/RBC volume ratios, or a trial exploring the effect on mortality of a reduction in transfused plasma volume. A potential general decrease in demand of plasma for transfusion would have obvious benefits to a country’s donor population and healthcare costs.
Limitations
In our analysis of blood product use and plasma transfu- sion safety, around 20% (3,559 of 17,861 episodes – see Figure 1) of the transfusion episodes involved transfusion of only plasma, without concurrent RBC units. This is not in line with current evidence-based indications for plasma transfusion which (if followed) would lead to plasma always being transfused with RBC units except in cases of plasma exchange (plasma exchange episodes comprise less than 1% of the transfusion episodes analyzed in our study).21 After review of a sample of these patients’ transfusion data we confirmed that data were not missing (i.e. that only plasma was transfused during these episodes). Previous studies have likewise pointed out a high rate of plasma transfusion out- side the context of evidence-based indications.2,22,23 As an example, in some of the reporting hospitals, plasma is trans- fused prophylactically prior to biopsy procedures.
The large standard deviations in mean plasma and RBC units transfused (Table 1) demonstrate the extent to which transfusion practice varied among the patients in our study. Further, we matched patients only on ward or diag- nosis without correcting for other predictors, as this was not the goal of our analysis. The conclusions are thus to be interpreted at a population level, and not at the level of the individual patient. Finally, given the rare nature of many of the transfusion reactions analyzed, even 6 years of data from a country performing only 60,000 plasma transfu- sions per year yields datasets too small for solid hemovig- ilance comparisons. Meta-analyses, large-scale observa- tional trials, or active hemovigilance studies are better equipped to address comparative safety of blood products with regard to rare adverse events.
Conclusions
Using national bood bank and hemovigilance data, as well as transfusion data from six large hospitals in the Netherlands, we compared FFP and SD plasma with regard to blood product use and transfusion reaction risk in the period surrounding the national switch from FFP to SD plasma in 2014. We found some small differences in the average number of RBC units transfused alongside SD plasma versus FFP, but no systemic changes in mean RBC transfused or the mean plasma/RBC units ratio when comparing the two products. This suggests the two plas- mas were transfused in the same ratio (by units) to RBC and that they do not differ significantly in their effective- ness at stopping bleeding at a unit level, despite the signif- icantly (one third) smaller volume of SD plasma units and their chemical similarity to FFP. SD plasma is associated with fewer allergic (other) and allergic (anaphylactic) transfusion reactions.
Acknowledgments
The authors wish to thank Yavanna van Oostveen and the data management team at Sanquin’s Centre for Clinical Transfusion Research (CCTR) for their collection and cleaning of the patient data used within this study and the Scientific Committee of the CCTR for their analytical advice.
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