Fewer severe infections with tranexamic acid in patients with hematologic malignancies

Background

Tranexamic acid (TXA) is an antifibrinolytic agent that reduces bleeding in a multitude of clinical settings from postpartum hemorrhage to trauma. TXA may have clinical effects unrelated to bleeding; plasminogen, the target of TXA, alters immune responses, and TXA appears to decrease the risk of infection in patients undergoing cardiac surgery, as well as joint arthroplasty.

Objectives

To address whether TXA alters rates of infection and inflammatory outcomes in patients with hematologic malignancies.

Methods

We performed a post hoc analysis of outcomes of patients randomized to receive either TXA or placebo in the double-blinded, multicenter American Trial to Evaluate Tranexamic Acid Therapy in Thrombocytopenia (Clinicaltrials.gov identifier: NCT02578901).

Results

TXA did not change the overall rate of infections, but the rate of severe infections (Common Toxicology Criteria for Adverse Events grade 3+) was lower in patients who received TXA compared with the placebo group. Patients who experienced grade 3+ infections had higher rates of World Health Organization grade 2+ bleeding and red blood cell transfusion requirements than patients who did not experience a grade 3+ infection, irrespective of treatment group. TXA did not impact other inflammatory outcomes such as mucositis, rash, or graft vs host disease.

Conclusion

Patients with hematologic malignancies who received TXA had less severe infections than those who received placebo with no difference in overall rate of infection or other inflammatory outcomes. Further investigation is needed on the impact of TXA on infections in this population.

Therapeutic plasma exchange is feasible and tolerable in severely injured patients with trauma-induced coagulopathy

Objectives

Trauma-induced coagulopathy (TIC) occurs in a subset of severely injured trauma patients. Despite having achieved surgical hemostasis, these individuals can have persistent bleeding, clotting, or both in conjunction with deranged coagulation parameters and typically require transfusion support with plasma, platelets, and/or cryoprecipitate. Due to the multifactorial nature of TIC, targeted interventions usually do not have significant clinical benefits. Therapeutic plasma exchange (TPE) is a non-specific modality of removing and replacing a patient's plasma in a euvolemic manner that can temporarily normalize coagulation parameters and remove deleterious substances, and may be beneficial in such patients with TIC.

Methods

In a prospective case series, TPE was performed in severely injured trauma patients diagnosed with TIC and transfusion requirement. These individuals all underwent a series of at least 3 TPE procedures performed once daily with plasma as the exclusive replacement fluid. Demographic, injury, laboratory, TPE, and outcome data were collected and analyzed.

Results

In total, 7 patients received 23 TPE procedures. All patients had marked improvements in routine coagulation parameters, platelet counts, a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) activities, inflammatory markers including interleukin-6 concentrations, and organ system injuries after completion of their TPE treatments. All-cause mortality rates at 1 day, 7 days, and 30 days were 0%, 0%, and 43%, respectively, and all patients for whom TPE was initiated within 24 hours after injury survived to the 30-day timepoint. Surgical, critical care, and apheresis nursing personnel who were surveyed were universally positive about the utilization of TPE in this patient population. These procedures were tolerated well with the most common adverse event being laboratory-diagnosed hypocalcemia.

Conclusion

TPE is feasible and tolerable in severely injured trauma patients with TIC. However, many questions remain regarding the application of TPE for these critically ill patients including identification of the optimal injured population, ideal time of treatment initiation, appropriate treatment intensity, and concurrent use of adjunctive treatments.

Level of evidence

Level V.

Another piece of the hemolytic disease of the fetus and newborn puzzle after RhD-positive transfusion in trauma resuscitation: the proportion of pregnant women who produce high titer anti-D

Background

After the transfusion of RhD-positive red blood cell (RBC)-containing products to an RhD-negative woman of childbearing potential (WCP) during trauma resuscitation, there are several events that must occur for that WCP to have a future pregnancy affected by hemolytic disease of the fetus and newborn (HDFN). This study identified and quantitated the frequency of a novel event in the sequence from RhD-positive transfusion during trauma resuscitation to an HDFN outcome, that is, the development of a high titer anti-D among women who were D-alloimmunized.

Methods

The transfusion service records at one maternity hospital were searched to locate all anti-D titers that had been performed on pregnant women between 1996 and 2022. The highest titer score during each pregnancy was recorded for this study. The critical titer threshold at this institution was ≥16. Passive anti-D caused by Rh immunoglobulin were excluded from analysis.

Results

There were 97 pregnancies in 85 patients who had an immune-stimulated anti-D; in 60 of 97 (62%) pregnancies, the highest titer score was ≥16. There were 12 patients who had titers performed in two pregnancies during the study period; the correlation between the maximum titer in each pregnancy was not statistically significant (Spearman rank correlation r=0.42, p=0.17).

Conclusion

In this single center study, 62% of D-alloimmunized pregnant women had a high titer antibody. When considering all of the events that must occur for HDFN to happen, the rate of perinatal mortality was calculated to be 0.04% and the rate of perinatal death or serious adverse event from HDFN was 0.24%.

Restrictive or Liberal Transfusion Strategy in Myocardial Infarction and Anemia

BACKGROUND

A strategy of administering a transfusion only when the hemoglobin level falls below 7 or 8 g per deciliter has been widely adopted. However, patients with acute myocardial infarction may benefit from a higher hemoglobin level.

METHODS

In this phase 3, interventional trial, we randomly assigned patients with myocardial infarction and a hemoglobin level of less than 10 g per deciliter to a restrictive transfusion strategy (hemoglobin cutoff for transfusion, 7 or 8 g per deciliter) or a liberal transfusion strategy (hemoglobin cutoff, <10 g per deciliter). The primary outcome was a composite of myocardial infarction or death at 30 days.

RESULTS

A total of 3504 patients were included in the primary analysis. The mean (±SD) number of red-cell units that were transfused was 0.7±1.6 in the restrictive-strategy group and 2.5±2.3 in the liberal-strategy group. The mean hemoglobin level was 1.3 to 1.6 g per deciliter lower in the restrictive-strategy group than in the liberal-strategy group on days 1 to 3 after randomization. A primary-outcome event occurred in 295 of 1749 patients (16.9%) in the restrictive-strategy group and in 255 of 1755 patients (14.5%) in the liberal-strategy group (risk ratio modeled with multiple imputation for incomplete follow-up, 1.15; 95% confidence interval [CI], 0.99 to 1.34; P = 0.07). Death occurred in 9.9% of the patients with the restrictive strategy and in 8.3% of the patients with the liberal strategy (risk ratio, 1.19; 95% CI, 0.96 to 1.47); myocardial infarction occurred in 8.5% and 7.2% of the patients, respectively (risk ratio, 1.19; 95% CI, 0.94 to 1.49).

CONCLUSIONS

In patients with acute myocardial infarction and anemia, a liberal transfusion strategy did not significantly reduce the risk of recurrent myocardial infarction or death at 30 days. However, potential harms of a restrictive transfusion strategy cannot be excluded. (Funded by the National Heart, Lung, and Blood Institute and others; MINT ClinicalTrials.gov number, NCT02981407.).

Incompatible plasma transfusion is not associated with increased mortality in civilian trauma patients

BACKGROUND

The introduction of low titer group O whole blood (LTOWB) that contains potentially ABO-incompatible plasma and the increasing use of group A plasma, due to shortages of AB plasma, in trauma patients whose ABO group is unknown could put the recipients of incompatible plasma at risk of increased morbidity and mortality. This study evaluated civilian trauma patient outcomes following receipt of incompatible plasma.

METHODS

One trauma center's patient contributions to three multicenter studies of different trauma resuscitation strategies was analyzed; these patients were separated into two groups based on receipt of only compatible plasma versus receipt of any quantity of incompatible plasma. Multivariate analysis was performed to determine if receipt of incompatible plasma was associated with 24-hour or 30-day mortality.

RESULTS

There were 347 patients eligible for this secondary analysis with 167 recipients of only compatible plasma and 180 recipients of incompatible plasma. The two groups were well matched demographically and on both prehospital and hospital arrival vital signs. The median (IQR) volume of incompatible plasma received by these patients was 684 ml (342, 1229). There was not a significant difference between the groups in 24-hour and 30-day mortality, nor in in-hospital or intensive care unit lengths of stay. In the Cox proportional-hazards regression model for both 24-hour and 30-day survival, receipt of incompatible plasma was not independently predictive of either mortality endpoint.

CONCLUSION

Receipt of incompatible plasma was not independently associated with increased mortality in trauma patients. Prospective studies are needed to confirm these findings.

Not as "D"eadly as once thought - the risk of D-alloimmunization and hemolytic disease of the fetus and newborn following RhD-positive transfusion in trauma

The use of blood products to resuscitate injured and massively bleeding patients in the prehospital and early in-hospital phase of the resuscitation is increasing. Using group O red blood cells (RBC) and low titer group O whole blood (LTOWB) avoids an immediate hemolytic reaction from recipient's naturally occurring anti-A and - B, but choosing the RhD type for these products is more nuanced and requires the balancing of product availability and survival benefit against the risk of D-alloimmunization, especially in females of childbearing potential (FCP) due to the possible future occurrence of hemolytic disease of the fetus and newborn (HDFN). Recent models have estimated the risk of fetal/neonatal death from HDFN resulting from D-alloimmunization of an FCP during her trauma resuscitation at between 0-6.5% depending on her age at the time of the transfusion and other societal factors including trauma mortality, her age when she becomes pregnant, frequency of different RHD genotypes in the population, and the probability that the woman will have children with different fathers; this is counterbalanced by an approximately 24% risk of death from hemorrhagic shock. This review will discuss the different models of HDFN outcomes following RhD-positive transfusion as well as the results of recent surveys where the public was asked about their preferences for urgent transfusion in light of the risks of fetal/neonatal adverse events.

Optimizing RBC Transfusion Outcomes in Patients with Acute Illness and in the Chronic Transfusion Setting

Red blood cell (RBC) transfusion is a common clinical intervention used to treat patients with acute and chronic anemia. The decision to transfuse RBCs in the acute setting is based on several factors but current clinical studies informing optimal RBC transfusion decision making (TDM) are largely based upon hemoglobin (Hb) level. In contrast to transfusion in acute settings, chronic RBC transfusion therapy has several different purposes and is associated with distinct transfusion risks such as iron overload and RBC alloimmunization. Consequently, RBC TDM in the chronic setting requires optimizing the survival of transfused RBCs in order to reduce transfusion exposure over the lifespan of an individual and the associated transfusion complications mentioned. This review summarizes the current medical literature addressing optimal RBC-TDM in the acute and chronic transfusion settings and discusses the current gaps in knowledge which need to be prioritized in future national and international research initiatives.

Prophylactic Platelet Transfusion: Is There Evidence of Benefit, Harm, or No Effect?

The optimal use of prophylactic platelet transfusion remains uncertain in a number of clinical scenarios. Platelet count thresholds have been established in patients with hematologic malignancies, yet thresholds backed by scientific data are limited or do not exist for many patient populations. Clinical scenarios involving transfusion thresholds for thrombocytopenic patients with critical illness, need for surgery or invasive procedures, or those involving specials populations like children and neonates, lack clear evidence for discerning favorable outcomes without undue risk related to platelet transfusion. In addition, while prophylactic platelet transfusions are administered with the goal of enhancing hemostasis, increasing evidence supports critical nonhemostatic roles for platelets related to innate and adaptive immunity, inflammation, and angiogenesis, which may impact patient responses and outcomes. Here we review several recent studies conducted in adult or pediatric patients that highlight the limitations in our current understanding of prophylactic platelet transfusion. Together, these studies underscore the need for additional research, especially in the form of robust randomized clinical trials and integrating additional parameters beyond the platelet count. Future research at the basic, translational, and clinical levels will best define the optimal role for prophylactic transfusion across the lifespan and its broader impact on health and disease.

How do we…consistently provide high-dose granulocyte products for transfusions in neutropenic patients?

BACKGROUND

The therapeutic use of granulocyte transfusions for the treatment of infections in immunocompromised patients has been a controversial practice. Randomized controlled trials suggest that benefit may be provided when a high-dose product, defined as providing a dose of at least 0.6 × 10⁹ /kg, is offered. Here we describe the collection process and granulocyte product yield over a four-year period at a donation center supplying a large, tertiary academic medical center.

METHODS

A retrospective chart review was performed for apheresis granulocyte donations collected between 2018 and 2021 following implementation of combined G-CSF and dexamethasone donor stimulation at our institution. Data collected includes donor demographics, G-CSF administration timeline, pre-collection cell counts, product yields, donor adverse events, and post-transfusion ANC increments.

RESULTS

A total of 269 granulocyte units were collected from 184 unique donors. The median neutrophil yield (ANC) following G-CSF implementation was 7.5 × 10¹⁰ /unit. The proportion of granulocyte products meeting or exceeding a yield of 4.0 × 10¹⁰ per unit was 96.5%. These products resulted in measurable median ANC increment of 550/μL in transfused adult patients (n = 166 transfusions).

DISCUSSION

In order to properly assess the effectiveness of granulocyte transfusions in patients, it is necessary to ensure that the products being transfused contain an adequate granulocyte dose. This study demonstrates that the combination of G-CSF and dexamethasone donor stimulation, followed by apheresis granulocyte collection, is safe and can reliably yield a high-dose product. Consistent production of high-dose units allows for better assessment of patient outcomes by reducing dosage variability.

Timing of RhD-positive red blood cell administration is associated with D-alloimmunization in injured patients

BACKGROUND

The D-alloimmunization rate in trauma patients does not appear to depend on the number of RhD-positive units transfused. The effect of the timing and pattern of RhD-positive transfusions has not been evaluated.

METHODS

RhD-negative trauma patients who were transfused with RhD-positive red blood cells (RBC) or low titer group O whole blood (collectively called RBCs) on at least two separate calendar days and who had antibody detection tests performed at least 14 days after the second RhD-positive RBC transfusion without receiving RhIg were included in the analysis. Patients whose anti-D was detected within 14 days of the index RhD-positive RBC transfusion were excluded. Patient demographics and the dates of RhD-positive RBC transfusions and results of antibody detection tests performed after the index transfusion were collected on eligible patients.

RESULTS

There were 44/61 (72.1%) patients in whom anti-D was not detected (non-alloimmunized) and 17/61 (27.9%) in whom anti-D was detected (alloimmunized). The patients had similar demographics with trends towards higher median admission heart rates and lower median admission Glasgow Coma Scale values in the alloimmunized group. Both groups received statistically identical median quantities of RhD-positive RBCs (non-alloimmunized 5 vs. alloimmunized 4 units, p = .53), however, the alloimmunized group received all their RhD-positive RBCs over a significantly shorter period of time compared to the non-alloimmunized (median 4 vs. 15 days, respectively, p = .01).

CONCLUSION

Receipt of all RhD-positive RBCs over a shorter period of time was associated with higher D-alloimmunization rates. These results need to be confirmed in larger studies.

Hemostatic in vitro Properties of Novel Plasma Supernatants Produced from Late-Storage Low-Titer Type O Whole Blood

BACKGROUND

The use of low-titer group O whole blood is increasing. To reduce wastage, unused units can be converted to packed red blood cells. Supernatant is currently discarded post-conversion; however, it could be a valuable transfusable product. The aim of this study was to evaluate supernatant prepared from late-storage low-titer group O whole blood being converted to red blood cells, hypothesizing it will have higher hemostatic activity compared to fresh never-frozen liquid plasma.

METHODS

Low-titer group O whole blood supernatant (n=12) prepared on storage day 15 was tested on day 15, 21, and 26 and liquid plasma (n=12) on 3, 15, 21, and 26. Same day assays included cell counts, rotational thromboelastometry, and thrombin generation. Centrifuged plasma from units was banked for microparticle characterization, conventional coagulation, clot structure, hemoglobin, and additional thrombin generation assays.

RESULTS

Low-titer group O whole blood supernatant contained more residual platelets and microparticles compared to liquid plasma. At day 15, low-titer group O whole blood supernatant elicited a faster intrinsic clotting time compared to liquid plasma (257 +/- 41 vs. 299 +/- 36 seconds, p=0.044), and increased clot firmness (49 +/- 9 vs. 28 +/- 5 mm, p<0.0001). Low-titer group O whole blood supernatant showed more significant thrombin generation compared to liquid plasma (day 15 endogenous thrombin potential 1071 +/- 315 vs. 285 +/- 221 nM*min, p<0.0001). Flow cytometry demonstrated low-titer group O whole blood supernatant contained significantly more phosphatidylserine and CD41+ microparticles. However, thrombin generation in isolated plasma suggested residual platelets in low-titer group O whole blood supernatant were a greater contributor over microparticles. Additionally, low-titer group O whole blood supernatant and liquid plasma showed no difference in clot structure, despite higher CD61+ microparticle presence.

CONCLUSIONS

Plasma supernatant produced from late-storage low-titer group O whole blood shows comparable, if not enhanced, in vitro hemostatic efficacy to liquid plasma.

Proceedings of the 2022 NHLBI and OASH state of the science in transfusion medicine symposium

BACKGROUND

State of the Science (SoS) meetings are used to define and highlight important unanswered scientific questions. The National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health, and the Office of the Assistant Secretary for Health (OASH), Department of Health and Human Services held a virtual SoS in transfusion medicine (TM) symposium.

STUDY DESIGN AND METHODS

In advance of the symposium, six multidisciplinary working groups (WG) convened to define research priorities in the areas of: blood donors and the supply, optimizing transfusion outcomes for recipients, emerging infections, mechanistic aspects of components and transfusion, new computational methods in transfusion science, and impact of health disparities on donors and recipients. The overall objective was to identify key basic, translational, and clinical research questions that will help to increase and diversify the volunteer donor pool, ensure safe and effective transfusion strategies for recipients, and identify which blood products from which donors best meet the clinical needs of specific recipient populations.

RESULTS

On August 29-30, 2022, over 400 researchers, clinicians, industry experts, government officials, community members, and patient advocates discussed the research priorities presented by each WG. Dialogue focused on the five highest priority research areas identified by each WG and included the rationale, proposed methodological approaches, feasibility, and barriers for success.

DISCUSSION

This report summarizes the key ideas and research priorities identified during the NHLBI/OASH SoS in TM symposium. The report highlights major gaps in our current knowledge and provides a road map for TM research.

Low Titer Group O Whole Blood In Injured Children Requiring Massive Transfusion

OBJECTIVE

The aim of this study was to assess the survival impact of low-titer group O whole blood (LTOWB) in injured pediatric patients who require massive transfusion.

SUMMARY BACKGROUND DATA

Limited data are available regarding the effectiveness of LTOWB in pediatric trauma.

METHODS

A prospective observational study of children requiring massive transfusion after injury at UPMC Children's Hospital of Pittsburgh, an urban academic pediatric Level 1 trauma center. Injured children ages 1 to 17 years who received a total of >40 mL/kg of LTOWB and/or conventional components over the 24 hours after admission were included. Patient characteristics, blood product utilization and clinical outcomes were analyzed using Kaplan-Meier survival curves, log rank tests and Cox proportional hazards regression analyses. The primary outcome was 28-day survival.

RESULTS

Of patients analyzed, 27 of 80 (33%) received LTOWB as part of their hemostatic resuscitation. The LTOWB group was comparable to the component therapy group on baseline demographic and physiologic parameters except older age, higher body weight, and lower red blood cell and plasma transfusion volumes. After adjusting for age, total blood product volume transfused in 24 hours, admission base deficit, international normalized ratio (INR), and injury severity score (ISS), children who received LTOWB as part of their resuscitation had significantly improved survival at both 72 hours and 28 days post-trauma [adjusted odds ratio (AOR) 0.23, P = 0.009 and AOR 0.41, P = 0.02, respectively]; 6-hour survival was not statistically significant (AOR = 0.51, P = 0.30). Survivors at 28 days in the LTOWB group had reduced hospital LOS, ICU LOS, and ventilator days compared to the CT group.

CONCLUSION

Administration of LTOWB during the hemostatic resuscitation of injured children requiring massive transfusion was independently associated with improved 72-hour and 28-day survival.

Absence of hyperfibrinolysis may explain lack of efficacy of tranexamic acid in hypoproliferative thrombocytopenia

The American Trial Using Tranexamic Acid (TXA) in Thrombocytopenia (A-TREAT, NCT02578901) demonstrated no superiority of TXA over placebo in preventing World Health Organization (WHO) grade 2 or higher bleeding in patients with severe thrombocytopenia requiring supportive platelet transfusion following myeloablative therapy for hematologic disorders. In this ancillary study, we sought to determine whether this clinical outcome could be explained on the basis of correlative assays of fibrinolysis. Plasma was collected from A-TREAT participants (n = 115) before the initiation of study drug (baseline) and when TXA was at steady-state trough concentration (follow-up). Global fibrinolysis was measured by 3 assays: euglobulin clot lysis time (ECLT), plasmin generation (PG), and tissue-type plasminogen activator (tPA)-challenged clot lysis time (tPA-CLT). TXA was quantified in follow-up samples by tandem mass spectrometry. Baseline samples did not demonstrate fibrinolytic activation by ECLT or tPA-CLT. Furthermore, neither ECLT nor levels of plasminogen activator inhibitor-1, tPA, plasminogen, alpha2-antiplasmin, or plasmin-antiplasmin complexes were associated with a greater risk of WHO grade 2+ bleeding. TXA trough concentrations were highly variable (range, 0.7-10 μg/mL) and did not correlate with bleeding severity, despite the fact that plasma TXA levels correlated strongly with pharmacodynamic assessments by PG (Spearman r, -0.78) and tPA-CLT (r, 0.74). We conclude that (1) no evidence of fibrinolytic activation was observed in these patients with thrombocytopenia, (2) trough TXA concentrations varied significantly between patients receiving the same dosing schedule, and (3) tPA-CLT and PG correlated well with TXA drug levels.

Receipt of low titer group O whole blood does not lead to hemolysis in children weighing less than 20 kilograms

OBJECTIVE

The safety of Low Titer Group O Whole Blood (LTOWB) transfusion has not been well-studied in small children.

METHODS

This is a single-center retrospective cohort study of pediatric recipients of RhD-LTOWB (June 2016-October 2022) who weigh less than 20 kilograms. Biochemical markers of hemolysis (lactate dehydrogenase, total bilirubin, haptoglobin, and reticulocyte count) and renal function (creatinine and potassium) were recorded on the day of LTOWB transfusion and post-transfusion days 1 and 2. Group O and non-Group O recipients were compared.

RESULTS

Twenty-one children were included. Their median (interquartile range [IQR]) weight was 12 kg (12-18) with minimum 2.8 kg, and median (IQR) age was 3 years (1.75-5.00) with minimum 0.08 years (29 days old). The most common indication for transfusion was trauma (17/21; 81%). The median (IQR) volume of LTOWB transfused was 30 mL/kg (20-42). There were 9 non-group O and 12 group O recipients. There were no statistically significant differences in the median concentrations of any of the biochemical markers of hemolysis or the renal function markers between the non-group O and the group O recipients at any of the three time points (p > 0.05 for all comparisons). There were also no statistically significant differences in demographic parameters or clinical outcomes including 28-day mortality, length of stay, ventilator days, and venous thromboembolism between the groups. No transfusion reactions were reported in either group.

CONCLUSION

These data suggest LTOWB use is safe in children weighing less than 20 kg. Further multi-center studies and larger cohorts are needed to confirm these results.

Rationale and design for the myocardial ischemia and transfusion (MINT) randomized clinical trial

BACKGROUND

Accumulating evidence from clinical trials suggests that a lower (restrictive) hemoglobin threshold (<8 g/dL) for red blood cell (RBC) transfusion, compared with a higher (liberal) threshold (≥10 g/dL) is safe. However, in anemic patients with acute myocardial infarction (MI), maintaining a higher hemoglobin level may increase oxygen delivery to vulnerable myocardium resulting in improved clinical outcomes. Conversely, RBC transfusion may result in increased blood viscosity, vascular inflammation, and reduction in available nitric oxide resulting in worse clinical outcomes. We hypothesize that a liberal transfusion strategy would improve clinical outcomes as compared to a more restrictive strategy.

METHODS

We will enroll 3500 patients with acute MI (type 1, 2, 4b or 4c) as defined by the Third Universal Definition of MI and a hemoglobin <10 g/dL at 144 centers in the United States, Canada, France, Brazil, New Zealand, and Australia. We randomly assign trial participants to a liberal or restrictive transfusion strategy. Participants assigned to the liberal strategy receive transfusion of RBCs sufficient to raise their hemoglobin to at least 10 g/dL. Participants assigned to the restrictive strategy are permitted to receive transfusion of RBCs if the hemoglobin falls below 8 g/dL or for persistent angina despite medical therapy. We will contact each participant at 30 days to assess clinical outcomes and at 180 days to ascertain vital status. The primary end point is a composite of all-cause death or recurrent MI through 30 days following randomization. Secondary end points include all-cause mortality at 30 days, recurrent adjudicated MI, and the composite outcome of all-cause mortality, nonfatal recurrent MI, ischemia driven unscheduled coronary revascularization (percutaneous coronary intervention or coronary artery bypass grafting), or readmission to the hospital for ischemic cardiac diagnosis within 30 days. The trial will assess multiple tertiary end points.

CONCLUSIONS

The MINT trial will inform RBC transfusion practice in patients with acute MI.

Optimizing interpretation of survival studies of fresh and aged transfused biotin-labeled RBCs

BACKGROUND

Ex vivo labeling with 51 chromium represents the standard method to determine red blood cell (RBC) survival after transfusion. Limitations and safety concerns spurred the development of alternative methods, including biotinylated red blood cells (BioRBC).

STUDY DESIGN AND METHODS

Autologous units of whole blood were divided equally into two bags and stored under standard blood bank conditions at 2 to 6°C (N = 4 healthy adult volunteers). One bag was biotinylated (15 μg/ml) on storage days 5 to 7 (fresh) and the other was biotinylated (3 μg/ml) on days 35 to 42 (aged). The proportion of circulating BioRBC was measured serially, and cell-surface biotin was quantified with reference to molecules of equivalent soluble fluorochrome. Clearance kinetics were modeled by RBC age distribution at infusion (Gaussian vs. uniform) and decay over time (constant vs. exponential).

RESULTS

Data were consistent with biphasic exponential clearance of cells of uniform age. Our best estimate of BioRBC clearance (half-life [T1/2 ]) was 49.7 ± 1.2 days initially, followed by more rapid clearance 82 days after transfusion (T1/2  = 15.6 ± 0.6 days). As BioRBC aged in vivo, molecules of equivalent soluble fluorochrome declined with a T1/2 of 122 ± 9 days, suggesting gradual biotin cleavage. There were no significant differences between the clearance of fresh and aged BioRBC.

CONCLUSION

Similar clearance kinetics of fresh and aged BioRBC may be due to the extensive washing required during biotinylation. Survival kinetics consistent with cells with uniform rather than Gaussian or other non-uniform age distributions suggest that washing, and potentially RBC culling, may extend the storage life of RBC products.

Receipt of at least 4 units of low titer group O whole blood with titer <100 does not lead to hemolysis in adult trauma patients

BACKGROUND

The serological safety of transfusing low titer group O whole blood (LTOWB) with an anti-A and anti-B titer of <100 was evaluated in group O and non-group O trauma recipients.

METHODS

Civilian adult trauma patients who received ≥4 units of leukoreduced LTOWB during their initial resuscitation and who survived for >24 h after admission at two level 1 trauma centers were included in this retrospective study. Lactate dehydrogenase (LDH), total bilirubin, haptoglobin, potassium, creatinine were evaluated on the day of LTOWB transfusion (day 0) and on the next 3 days.

RESULTS

There were 77 injured recipients evaluated: 39 non-group O and 38 group O. The median (IQR) number of transfused LTOWB units was 4 (4-6) and 4 (4-5), respectively, and the maximum number of units was 8 and 11, respectively. The non-group O patients received a median (IQR) volume of 1710 ml (1368-2070) of ABO-incompatible plasma. Comparing non-group O to group O recipients, there were no significant differences in the median haptoglobin, LDH, or creatinine concentrations at any time point. The median concentration of total bilirubin was significantly higher amongst the non-group O recipients on days 1 and 2, while on day 0 the median potassium concentration was significantly higher amongst the group O recipients. All median elevated values were within the laboratory's normal range. Amongst the non-group O recipients there were no reported transfusion reactions.

CONCLUSION

Receiving at least four LTOWB units (anti-A&B titer <100) was not associated with biochemical/clinical evidence of hemolysis in adult trauma patients.

CD4+ T-Cell Dysfunction in Severe COVID-19 Disease Is Tumor Necrosis Factor-α/Tumor Necrosis Factor Receptor 1-Dependent

Rationale: Lymphopenia is common in severe coronavirus disease (COVID-19), yet the immune mechanisms are poorly understood. As inflammatory cytokines are increased in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, we hypothesized a role in contributing to reduced T-cell numbers. Objectives: We sought to characterize the functional SARS-CoV-2 T-cell responses in patients with severe versus recovered, mild COVID-19 to determine whether differences were detectable. Methods: Using flow cytometry and single-cell RNA sequence analyses, we assessed SARS-CoV-2-specific responses in our cohort. Measurements and Main Results: In 148 patients with severe COVID-19, we found lymphopenia was associated with worse survival. CD4⁺ lymphopenia predominated, with lower CD4⁺/CD8⁺ ratios in severe COVID-19 compared with patients with mild disease (P < 0.0001). In severe disease, immunodominant CD4⁺ T-cell responses to Spike-1 (S1) produced increased in vitro TNF-α (tumor necrosis factor-α) but demonstrated impaired S1-specific proliferation and increased susceptibility to activation-induced cell death after antigen exposure. CD4⁺TNF-α⁺ T-cell responses inversely correlated with absolute CD4⁺ counts from patients with severe COVID-19 (n = 76; R = -0.797; P < 0.0001). In vitro TNF-α blockade, including infliximab or anti-TNF receptor 1 antibodies, strikingly rescued S1-specific CD4⁺ T-cell proliferation and abrogated S1-specific activation-induced cell death in peripheral blood mononuclear cells from patients with severe COVID-19 (P < 0.001). Single-cell RNA sequencing demonstrated marked downregulation of type-1 cytokines and NFκB signaling in S1-stimulated CD4⁺ cells with infliximab treatment. We also evaluated BAL and lung explant CD4⁺ T cells recovered from patients with severe COVID-19 and observed that lung T cells produced higher TNF-α compared with peripheral blood mononuclear cells. Conclusions: Together, our findings show CD4⁺ dysfunction in severe COVID-19 is TNF-α/TNF receptor 1-dependent through immune mechanisms that may contribute to lymphopenia. TNF-α blockade may be beneficial in severe COVID-19.

Prehospital low titer group O whole blood is feasible and safe: Results of a prospective randomized pilot trial

INTRODUCTION

Low titer group O whole blood (LTOWB) resuscitation is increasingly common in both military and civilian settings. Data regarding the safety and efficacy of prehospital LTOWB remain limited.

METHODS

We performed a single-center, prospective, cluster randomized, prehospital through in-hospital whole blood pilot trial for injured air medical patients. We compared standard prehospital air medical care including red cell transfusion and crystalloids followed by in-hospital component transfusion to prehospital and in-hospital LTOWB resuscitation. Prehospital vital signs were used as inclusion criteria (systolic blood pressure ≤90 mm Hg and heart rate ≥108 beats per minute or systolic blood pressure ≤70 mm Hg for patients at risk of hemorrhage). Primary outcome was feasibility. Secondary outcomes included 28-day and 24-hour mortality, multiple organ failure, nosocomial infection, 24-hour transfusion requirements, and arrival coagulation parameters.

RESULTS

Between November 2018 and October 2020, 86 injured patients were cluster randomized by helicopter base. The trial has halted early at 77% enrollment. Overall, 28-day mortality for the cohort was 26%. Injured patients randomized to prehospital LTOWB (n = 40) relative to standard care (n = 46) were similar in demographics and injury characteristics. Intent-to-treat Kaplan-Meier survival analysis demonstrated no statistical mortality benefit at 28 days (25.0% vs. 26.1%, p = 0.85). Patients randomized to prehospital LTOWB relative to standard care had lower red cell transfusion requirements at 24 hours (p < 0.01) and a lower incidence of abnormal thromboelastographic measurements. No transfusion reactions during the prehospital or in-hospital phase of care were documented.

CONCLUSION

Prehospital through in-hospital LTOWB resuscitation is safe and may be associated with hemostatic benefits. A large-scale clinical trial is feasible with protocol adjustment and would allow the effects of prehospital LTOWB on survival and other pertinent clinical outcomes to be appropriately characterized.

LEVEL OF EVIDENCE

Therapeutic/Care Management, Level II.

Sex-specific genetic modifiers identified susceptibility of cold stored red blood cells to osmotic hemolysis

Background

Genetic variants have been found to influence red blood cell (RBC) susceptibility to hemolytic stress and affect transfusion outcomes and the severity of blood diseases. Males have a higher susceptibility to hemolysis than females, but little is known about the genetic mechanism contributing to the difference.

Results

To investigate the sex differences in RBC susceptibility to hemolysis, we conducted a sex-stratified genome-wide association study and a genome-wide gene-by-sex interaction scan in a multi-ethnic dataset with 12,231 blood donors who have in vitro osmotic hemolysis measurements during routine blood storage. The estimated SNP-based heritability for osmotic hemolysis was found to be significantly higher in males than in females (0.46 vs. 0.41). We identified SNPs associated with sex-specific susceptibility to osmotic hemolysis in five loci (SPTA1, KCNA6, SLC4A1, SUMO1P1, and PAX8) that impact RBC function and hemolysis.

Conclusion

Our study established a best practice to identify sex-specific genetic modifiers for sexually dimorphic traits in datasets with mixed ancestries, providing evidence of different genetic regulations of RBC susceptibility to hemolysis between sexes. These and other variants may help explain observed sex differences in the severity of hemolytic diseases, such as sickle cell and malaria, as well as the viability of red cell storage and recovery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08461-4.

Early Convalescent Plasma for High-Risk Outpatients with Covid-19

BACKGROUND

Early administration of convalescent plasma obtained from blood donors who have recovered from coronavirus disease 2019 (Covid-19) may prevent disease progression in acutely ill, high-risk patients with Covid-19.

METHODS

In this randomized, multicenter, single-blind trial, we assigned patients who were being treated in an emergency department for Covid-19 symptoms to receive either one unit of convalescent plasma with a high titer of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or placebo. All the patients were either 50 years of age or older or had one or more risk factors for disease progression. In addition, all the patients presented to the emergency department within 7 days after symptom onset and were in stable condition for outpatient management. The primary outcome was disease progression within 15 days after randomization, which was a composite of hospital admission for any reason, seeking emergency or urgent care, or death without hospitalization. Secondary outcomes included the worst severity of illness on an 8-category ordinal scale, hospital-free days within 30 days after randomization, and death from any cause.

RESULTS

A total of 511 patients were enrolled in the trial (257 in the convalescent-plasma group and 254 in the placebo group). The median age of the patients was 54 years; the median symptom duration was 4 days. In the donor plasma samples, the median titer of SARS-CoV-2 neutralizing antibodies was 1:641. Disease progression occurred in 77 patients (30.0%) in the convalescent-plasma group and in 81 patients (31.9%) in the placebo group (risk difference, 1.9 percentage points; 95% credible interval, -6.0 to 9.8; posterior probability of superiority of convalescent plasma, 0.68). Five patients in the plasma group and 1 patient in the placebo group died. Outcomes regarding worst illness severity and hospital-free days were similar in the two groups.

CONCLUSIONS

The administration of Covid-19 convalescent plasma to high-risk outpatients within 1 week after the onset of symptoms of Covid-19 did not prevent disease progression. (SIREN-C3PO ClinicalTrials.gov number, NCT04355767.).

Effect of Convalescent Plasma on Organ Support-Free Days in Critically Ill Patients With COVID-19: A Randomized Clinical Trial

IMPORTANCE

The evidence for benefit of convalescent plasma for critically ill patients with COVID-19 is inconclusive.

OBJECTIVE

To determine whether convalescent plasma would improve outcomes for critically ill adults with COVID-19.

DESIGN, SETTING, AND PARTICIPANTS

The ongoing Randomized, Embedded, Multifactorial, Adaptive Platform Trial for Community-Acquired Pneumonia (REMAP-CAP) enrolled and randomized 4763 adults with suspected or confirmed COVID-19 between March 9, 2020, and January 18, 2021, within at least 1 domain; 2011 critically ill adults were randomized to open-label interventions in the immunoglobulin domain at 129 sites in 4 countries. Follow-up ended on April 19, 2021.

INTERVENTIONS

The immunoglobulin domain randomized participants to receive 2 units of high-titer, ABO-compatible convalescent plasma (total volume of 550 mL ± 150 mL) within 48 hours of randomization (n = 1084) or no convalescent plasma (n = 916).

MAIN OUTCOMES AND MEASURES

The primary ordinal end point was organ support-free days (days alive and free of intensive care unit-based organ support) up to day 21 (range, -1 to 21 days; patients who died were assigned -1 day). The primary analysis was an adjusted bayesian cumulative logistic model. Superiority was defined as the posterior probability of an odds ratio (OR) greater than 1 (threshold for trial conclusion of superiority >99%). Futility was defined as the posterior probability of an OR less than 1.2 (threshold for trial conclusion of futility >95%). An OR greater than 1 represented improved survival, more organ support-free days, or both. The prespecified secondary outcomes included in-hospital survival; 28-day survival; 90-day survival; respiratory support-free days; cardiovascular support-free days; progression to invasive mechanical ventilation, extracorporeal mechanical oxygenation, or death; intensive care unit length of stay; hospital length of stay; World Health Organization ordinal scale score at day 14; venous thromboembolic events at 90 days; and serious adverse events.

RESULTS

Among the 2011 participants who were randomized (median age, 61 [IQR, 52 to 70] years and 645/1998 [32.3%] women), 1990 (99%) completed the trial. The convalescent plasma intervention was stopped after the prespecified criterion for futility was met. The median number of organ support-free days was 0 (IQR, -1 to 16) in the convalescent plasma group and 3 (IQR, -1 to 16) in the no convalescent plasma group. The in-hospital mortality rate was 37.3% (401/1075) for the convalescent plasma group and 38.4% (347/904) for the no convalescent plasma group and the median number of days alive and free of organ support was 14 (IQR, 3 to 18) and 14 (IQR, 7 to 18), respectively. The median-adjusted OR was 0.97 (95% credible interval, 0.83 to 1.15) and the posterior probability of futility (OR <1.2) was 99.4% for the convalescent plasma group compared with the no convalescent plasma group. The treatment effects were consistent across the primary outcome and the 11 secondary outcomes. Serious adverse events were reported in 3.0% (32/1075) of participants in the convalescent plasma group and in 1.3% (12/905) of participants in the no convalescent plasma group.

CONCLUSIONS AND RELEVANCE

Among critically ill adults with confirmed COVID-19, treatment with 2 units of high-titer, ABO-compatible convalescent plasma had a low likelihood of providing improvement in the number of organ support-free days.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02735707.

Effect of Convalescent Plasma on Organ Support-Free Days in Critically Ill Patients With COVID-19: A Randomized Clinical Trial

IMPORTANCE

The evidence for benefit of convalescent plasma for critically ill patients with COVID-19 is inconclusive.

OBJECTIVE

To determine whether convalescent plasma would improve outcomes for critically ill adults with COVID-19.

DESIGN, SETTING, AND PARTICIPANTS

The ongoing Randomized, Embedded, Multifactorial, Adaptive Platform Trial for Community-Acquired Pneumonia (REMAP-CAP) enrolled and randomized 4763 adults with suspected or confirmed COVID-19 between March 9, 2020, and January 18, 2021, within at least 1 domain; 2011 critically ill adults were randomized to open-label interventions in the immunoglobulin domain at 129 sites in 4 countries. Follow-up ended on April 19, 2021.

INTERVENTIONS

The immunoglobulin domain randomized participants to receive 2 units of high-titer, ABO-compatible convalescent plasma (total volume of 550 mL ± 150 mL) within 48 hours of randomization (n = 1084) or no convalescent plasma (n = 916).

MAIN OUTCOMES AND MEASURES

The primary ordinal end point was organ support-free days (days alive and free of intensive care unit-based organ support) up to day 21 (range, -1 to 21 days; patients who died were assigned -1 day). The primary analysis was an adjusted bayesian cumulative logistic model. Superiority was defined as the posterior probability of an odds ratio (OR) greater than 1 (threshold for trial conclusion of superiority >99%). Futility was defined as the posterior probability of an OR less than 1.2 (threshold for trial conclusion of futility >95%). An OR greater than 1 represented improved survival, more organ support-free days, or both. The prespecified secondary outcomes included in-hospital survival; 28-day survival; 90-day survival; respiratory support-free days; cardiovascular support-free days; progression to invasive mechanical ventilation, extracorporeal mechanical oxygenation, or death; intensive care unit length of stay; hospital length of stay; World Health Organization ordinal scale score at day 14; venous thromboembolic events at 90 days; and serious adverse events.

RESULTS

Among the 2011 participants who were randomized (median age, 61 [IQR, 52 to 70] years and 645/1998 [32.3%] women), 1990 (99%) completed the trial. The convalescent plasma intervention was stopped after the prespecified criterion for futility was met. The median number of organ support-free days was 0 (IQR, -1 to 16) in the convalescent plasma group and 3 (IQR, -1 to 16) in the no convalescent plasma group. The in-hospital mortality rate was 37.3% (401/1075) for the convalescent plasma group and 38.4% (347/904) for the no convalescent plasma group and the median number of days alive and free of organ support was 14 (IQR, 3 to 18) and 14 (IQR, 7 to 18), respectively. The median-adjusted OR was 0.97 (95% credible interval, 0.83 to 1.15) and the posterior probability of futility (OR <1.2) was 99.4% for the convalescent plasma group compared with the no convalescent plasma group. The treatment effects were consistent across the primary outcome and the 11 secondary outcomes. Serious adverse events were reported in 3.0% (32/1075) of participants in the convalescent plasma group and in 1.3% (12/905) of participants in the no convalescent plasma group.

CONCLUSIONS AND RELEVANCE

Among critically ill adults with confirmed COVID-19, treatment with 2 units of high-titer, ABO-compatible convalescent plasma had a low likelihood of providing improvement in the number of organ support-free days.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02735707.

The rebirth of the cool: a narrative review of the clinical outcomes of cold stored low titer group O whole blood recipients compared to conventional component recipients in trauma

There has been renewed interest in the use of low titer group O whole blood (LTOWB) for the resuscitation of civilian casualties. LTOWB offers several advantages over conventional components such as providing balanced resuscitation in one bag that contains less additive/preservative solution than an equivalent volume of conventional components, is easier and faster to transfuse than multiple components, avoids blood product ratio confusion, contains cold stored platelets, and reduces donor exposures. The resurgence in its use in the resuscitation of civilian trauma patients has led to the publication of an increasing number of studies on its use, primarily amongst adult recipients but also in pediatric patients. These studies have indicated that hemolysis does not occur amongst adult and pediatric non-group O recipients of a modest quantity of LTOWB. The published studies to date on mortality have shown conflicting results with some demonstrating a reduction following LTOWB transfusion while most others have not shown a reduction; there have not been any studies to date that have found significantly increased overall mortality amongst LTOWB recipients. Similarly, when other clinical outcomes, such as venous thromboembolism, sepsis, hospital or intensive care unit lengths of stay are evaluated, LTOWB recipients have not demonstrated worse outcomes compared to conventional component recipients. While definitive proof of the trends in these morbidity and mortality outcomes awaits confirmation in randomized controlled trials, the evidence to date indicates the safety of transfusing LTOWB to injured civilians.

Safety profile of low-titer group O whole blood in pediatric patients with massive hemorrhage

BACKGROUND

Low-titer Group O Whole Blood (LTOWB) is used with increasing frequency in adult and pediatric trauma and massive bleeding transfusion protocols. There is a risk of acute hemolytic reactions in non-group O recipients due to the passive transfusion of anti-A and anti-B in the LTOWB. This study investigated the hemolysis risk among pediatric recipients of LTOWB.

STUDY DESIGN AND METHODS

Blood bank records were queried for pediatric recipients of LTOWB between June 2016 and August 2020 and merged with clinical data. The primary outcome was laboratory evidence of hemolysis as manifested by changes in lactate dehydrogenase (LDH), haptoglobin, total bilirubin, reticulocyte count, potassium, and creatinine. Per protocol, these values were collected on hospital days 0-2 for recipients of LTOWB. Transfusion reactions were reported to the hospital's blood bank.

RESULTS

Forty-seven children received LTOWB transfusion between 2016 and 2020; 21 were group O and 26 were non-group O. The groups were comparable in terms of the total volume of transfused blood products, demographics, and clinical outcomes. The most common indication for LTOWB transfusion was hemorrhagic shock due to trauma. There were no clinically or statistically significant differences in baseline, post-transfusion day 1, or post-transfusion day 2 hemolysis markers between the group O and non-group O LTOWB recipients. There were no adverse events or transfusion reactions reported.

DISCUSSION

Use of up to 40 ml/kg of LTOWB appears to be serologically safe for children in hemorrhagic shock.

Rate of RhD-alloimmunization after the transfusion of multiple RhD-positive primary red blood cell-containing products

INTRODUCTION

Early transfusion reduces mortality in bleeding patients. In this setting, RhD-positive blood products might be transfused. This study determined the association between the RhD-alloimmunization rate and the number of RhD-positive products transfused.

METHODS

RhD-negative patients between 13 and 50 years who were transfused with ≥1 RhD-positive red blood cell (RBC) or whole blood units between January 1, 2000 and December 31, 2019 in a healthcare network were identified. Study patients had to have had at least one antibody detection test performed ≥14 days after the index RhD-positive transfusion and not receive RhIg. Patients were stratified into groups that received 1, 2, 3-5, 6-10, 11-20, and >20 RhD-positive transfusions and the RhD-alloimmunization rate was determined for each group.

RESULTS

There were 335 patients included; 52/335 (15.5%) were females. Overall, there were 117/335 (34.9%, CI: 29.8%-40.3%) recipients who became RhD-alloimmunized. There was no significant dosage effect in the RhD-alloimmunization rates as the exposure to RhD-positive units increased from one RhD-positive unit to more than 20 RhD-positive units (p = .270 for non-parametric trend test). In an exploratory analysis, patients who received 100% of their RhD-positive transfusions within 72 h of the index transfusion had a significantly higher rate of RhD-alloimmunization compared to those who were transfused over a longer period of time (42.3% vs. 21.4%, respectively; p = .001).

CONCLUSION

These results suggest that there may not be an increased RhD-alloimmunization risk with transfusing multiple RhD-positive units after one RhD-positive unit has been transfused. These findings need confirmation in larger studies.

An unusual case of anti-D detection in two consecutive D+ patient samples: Antibody carryover on an automated gel platform

BACKGROUND

Laboratory results can be affected by sample to sample carryover. Carryover of different analytes occurring in automated clinical chemistry, immunology, hematology, and molecular laboratories is well described. However, carryover in a transfusion service laboratory is not reported in medical literature.

MATERIALS AND METHODS

Immunohematology testing results, demographic data, and clinical data were reviewed on three patients retrospectively from 2015 to 2019.

RESULTS

Type and screen samples tested on automated gel platform from two D+ patients were affected by anti-D carryover from a patient sample with a very high-titer anti-D. Additional immunohematology and molecular testing confirmed that anti-D in samples of two D+ patients was due to carryover.

CONCLUSION

A case of anti-D carryover caused false detection of anti-D in two D+ patients. Carryover can have implications for patient management. Transfusion laboratory staff need to be aware of it and investigate any unexpected results further.

Plasma trial: Pilot randomized clinical trial to determine safety and efficacy of plasma transfusions

BACKGROUND

Plasma is frequently administered to patients with prolonged INR prior to invasive procedures. However, there is limited evidence evaluating efficacy and safety.

STUDY DESIGN AND METHODS

We performed a pilot trial in hospitalized patients with INR between 1.5 and 2.5 undergoing procedures conducted outside the operating room. We excluded patients undergoing procedures proximal to the central nervous system, platelet counts <40,000/μl, or congenital or acquired coagulation disorders unresponsive to plasma. We randomly allocated patients stratified by hospital and history of cirrhosis to receive plasma transfusion (10-15 cc/kg) or no transfusion. The primary outcome was change in hemoglobin concentration within 2 days of procedure.

RESULTS

We enrolled 57 patients, mean age 56.0, 34 (59.6%) with cirrhosis, and mean INR 1.92 (SD = 0.27). In the intention to treat analysis, there were 10 of 27 (38.5%) participants in the plasma arm with a post procedure INR <1.5 and one of 30 (3.6%) in the no treatment arm (p < .01). The mean INR after receiving plasma transfusion was -0.24 (SD 0.26) lower than baseline. The change from pre-procedure hemoglobin level to lowest level within 2 days was -0.6 (SD = 1.0) in the plasma transfusion arm and -0.4 (SD = 0.6) in the no transfusion arm (p = .29). Adverse outcomes were uncommon.

DISCUSSION

We found no differences in change in hemoglobin concentration in those treated with plasma compared to no treatment. The change in INR was small and corrected to less than 1.5 in minority of patients. Large trials are required to establish if plasma is safe and efficacious.

Adverse events after low titer group O whole blood versus component product transfusion in pediatric trauma patients: A propensity-matched cohort study

BACKGROUND

Low titer group O whole blood (LTOWB) is used as the initial resuscitative fluid in an increasing number of pediatric trauma and massive bleeding transfusion protocols. There is little data on adverse events following its transfusion in pediatric trauma patients.

STUDY DESIGN AND METHODS

Blood bank records were queried for pediatric recipients of at least one unit of red blood cells (RBCs) (component group) or LTOWB (LTOWB group) within 24 h of admission between May 2013 and August 2020. Subjects with early death (<72 h) were excluded. Propensity-score matching of LTOWB and component groups was performed. Adverse events were recorded, including transfusion reaction, thromboembolism, acute kidney injury, sepsis, and organ failure based on PELOD-2 score, along with hospital and ICU length of stay (LOS) and ventilator days.

RESULTS

Thirty-six LTOWB recipients were matched to 36 conventional component recipients. Subjects were 52% male, with blunt injury mechanism (82%), median (IQR) injury severity score = 27 (21-35), and 26% in-hospital mortality. The groups were well matched in terms of demographics and injury characteristics. There were no clinically or statistically significant differences in adverse outcomes including reported transfusion reaction, organ failure, acute kidney injury, sepsis/bacteremia, and venous thromboembolism. Hospital LOS, ventilator days, mortality, and functional disability at discharge were also not significantly different. The LTOWB group had significantly shorter ICU LOS compared to the component group.

CONCLUSION

LTOWB transfusion did not increase the risk of adverse events in children. However, larger studies are required to confirm these results.

Injured recipients of low-titer group O whole blood have similar clinical outcomes compared to recipients of conventional component therapy: A single-center, retrospective study

INTRODUCTION

Low-titer group O whole blood (LTOWB) is being increasingly transfused to injured patients. This study evaluated a range of clinical outcomes to determine if receipt of LTOWB predisposed recipients to worse outcomes compared to recipients of conventional component therapy (CCT).

METHODS

A retrospective analysis of trauma patients who received at least 3 units of LTOWB (LTOWB group) versus those that received at least 3 units of RBCs, 1 unit of plasma and 1 unit of platelets but no LTOWB (CCT group) during the first 24 h of their admission was performed. Causal treatment effects were explored using propensity score matching (PSM) and coarsened exact matching (CEM). Important clinical outcomes were evaluated.

RESULTS

There were 165 CCT and 155 LTOWB recipients eligible for matching. PSM and CEM reduced covariate imbalances between the CCT and LTOWB groups, with the exception that males remained over-represented in the LTOWB group due to the hospital's former resuscitation policy of not administering RhD-positive LTOWB to females <50. In both of the matched analyses, the LTOWB group received a median of 4 LTOWB units. There were no significant differences in 6-, 24-h mortality or 30-day mortality between groups, nor were there differences in the frequency of other clinical outcomes such as acute kidney injury, sepsis, venous/arterial thromboembolism; delta MODS was lower for the LTOWB recipients in the exact match group.

CONCLUSION

In both matched analyses, administration of a median of four LTOWB units did not result in a different frequency of major clinical outcomes including mortality.

The risk to future pregnancies of transfusing Rh(D)-negative females of childbearing potential with Rh(D)-positive red blood cells during trauma resuscitation is dependent on their age at transfusion

BACKGROUND

A risk assessment model for predicting the risk of haemolytic disease of the fetus and newborn (HDFN) in future pregnancies following the transfusion of Rh(D)-positive red blood cell (RBC)-containing products to females of childbearing potential (FCP) was developed, accounting for the age that the FCP is transfused in various countries.

METHODS

The HDFN risk prediction model included the following inputs: risk of FCP death in trauma, Rh(D) alloimmunization rate following Rh(D)-positive RBC transfusion, expected number of live births following resuscitation, probability of carrying an Rh(D)-positive fetus, the probability of HDFN in an Rh(D)-positive fetus carried by an alloimmunized mother. The model was implemented in Microsoft R Open, and one million FCPs of each age between 18 and 49 years old were simulated. Published data from eight countries, including the United States, were utilized to generate country-specific HDFN risk estimates.

RESULTS

The risk predictions showed similar characteristics for each country in that the overall risk of having a pregnancy affected by HDFN was higher if the FCP was younger when she received her Rh(D)-positive transfusion than if she was older. In the United States, the overall risk of HDFN if the FCP was transfused at age 18 was 3·4% (mild: 1·20%, moderate: 0·45%; severe: 1·15%; IUFD: 0·57%); the risk was approximately 0% if the FCP was 43 years or older at the time of transfusion.

CONCLUSION

This model can be used to predict HDFN outcomes when establishing transfusion policies as it relates to the administration of Rh(D)-positive products for massively bleeding FCPs.

Randomized controlled trial of 7, 28, vs 42 day stored red blood cell transfusion on oxygen delivery (VO2 max) and exercise duration

BACKGROUND

Few studies have rigorously assessed the impact of red blood cell (RBC) transfusion on oxygen delivery. Several large trials demonstrated no clinical outcome differences between transfusion of shorter-storage vs prolonged-storage RBCs. These trials did not directly assess functional measures of oxygen delivery. Therefore, it is not clear if 42-day stored RBCs deliver oxygen as effectively as 7-day stored RBCs.

STUDY DESIGN AND METHODS

Leukocyte-reduced RBCs were collected by apheresis in AS-3. Thirty subjects were randomized (1:1:1) to receive 2 units of autologous RBCs at either 7, 28, or 42 days following donation. VO₂ max testing, using a standardized protocol to exhaustion, was performed 2 days before (Monday) and 2 days after (Friday) the transfusion visit (Wednesday). The primary endpoint was the percent increase in VO₂ max between Monday and Friday. The secondary endpoint was the percent change in duration of exercise for the same time points.

RESULTS

Hemoglobin levels decreased by 2.8 ± 1.4 g/dL after donation and increased by 2.1 ± 0.6 g/dL after transfusion. This change in hemoglobin was associated with expected decreases (then increases after transfusion) in VO₂ max and exercise duration. No differences were observed between 7-day and 42-day RBC transfusion for percent increase in median [IQR] VO₂ max (10.5 [0.2-17.3] vs 10.9 [5.7-16.8], P = .41) or for percent increase in exercise duration (5.4 [4.1-6.9] vs 4.9 [2.0-7.2], P = .91), respectively. Results were similar for 28-day RBCs and were consistent across the ITT and per-protocol analysis populations.

CONCLUSION

These data indicate that 42-day, 28-day, and 7-day RBCs have similar ability to deliver oxygen.

How well do platelets prevent bleeding?

Prophylactic platelet transfusions are used to reduce the risk of spontaneous bleeding in patients with treatment- or disease-related severe thrombocytopenia. A prophylactic platelet-transfusion threshold of <10 × 103/µL has been shown to be safe in stable hematology/oncology patients. A higher threshold and/or larger or more frequent platelet doses may be appropriate for patients with clinical features associated with an increased risk of bleeding such as high fevers, sepsis, disseminated intravascular coagulation, anticoagulation therapy, or splenomegaly. Unique factors in the outpatient setting may support the use of a higher platelet-transfusion threshold and/or dose of platelets. A prophylactic platelet-transfusion strategy has been shown to be associated with a lower risk of bleeding compared with no prophylaxis in adult patients receiving chemotherapy but not for autologous transplant recipients. Despite the use of prophylactic platelet transfusions, a high incidence (50% to 70%) of spontaneous bleeding remains. Using a higher threshold or larger doses of platelets does not change this risk. New approaches to reduce the risk of spontaneous bleeding, including antifibrinolytic therapy, are currently under study.

NT-proBNP levels in the identification and classification of pulmonary transfusion reactions

BACKGROUND

Consensus definitions for transfusion-related acute lung injury (TRALI) and transfusion-associated circulatory overload (TACO) have recently been revised; however, pulmonary transfusion reactions remain difficult to diagnose. We hypothesized that N-terminal pro-brain natriuretic peptide (NT-proBNP) levels could have utility in the identification and classification of pulmonary transfusion reactions.

STUDY DESIGN AND METHODS

We performed a secondary analysis of a case-control study of pulmonary transfusion reactions at four academic hospitals. We evaluated clinical data and measured NT-proBNP levels prior to and following transfusion in patients with TACO (n = 160), transfused acute respiratory distress syndrome (ARDS) [n = 51], TRALI [n = 12], TACO/TRALI [n = 7], and controls [n = 335]. We used Wilcoxon Rank-Sum tests to compare NT-proBNP levels, and classification and regression tree (CART) algorithms to produce a ranking of covariates in order of relative importance for differentiating TACO from transfused controls.

RESULTS

Pre-transfusion NT-proBNP levels were elevated in cases of transfused ARDS and TACO (both P < .001) but not TRALI (P = .31) or TACO/TRALI (P = .23) compared to transfused controls. Pre-transfusion NT-proBNP levels were higher in cases of transfused ARDS or TRALI with a diagnosis of sepsis compared to those without (P < .05 for both). CART analyses resulted in similar differentiation of patients with TACO from transfused controls for models utilizing either NT-proBNP levels (AUC 0.83) or echocardiogram results (AUC 0.80).

CONCLUSIONS

NT-proBNP levels may have utility in the classification of pulmonary transfusion reactions. Prospective studies are needed to test the predictive utility of pre-transfusion NT-proBNP in conjunction with other clinical factors in identifying patients at risk of pulmonary transfusion reactions.

Optimizing blood bank resources when implementing a low-titer group O+ whole blood program: an in silico study

INTRODUCTION

Low-titer group O+ whole blood (LTOWB) is becoming commonly used in massive bleeding resuscitation, but the impact on blood center O+ RBCs has not been studied. This in silico model simulated a variety of different LTOWB production and utilization patterns.

METHODS

Collections and distributions data from a large blood collector were scaled to vary the total number of O+ red blood cell (RBC) collections, the O+ RBC collection: import ratio, and the O+ RBC apheresis: whole blood (WB) collection ratio. Daily LTOWB demand was determined by the daily number of LTOWB recipients, average number of LTOWB units transfused per patient, maximum number of LTOWB units a single patient can receive, and seasonality of LTOWB use. LTOWB program factors included the high-titer exclusion %, the LTOWB expiry, and whether LTOWB units were reclaimed as O+ RBC units on the date of expiry. Simulations using unique combinations of the above input parameters were performed.

RESULTS

For the 1,224,720 unique combinations of input parameters simulated, the average increase in the fraction of additional O+ RBC units required to meet hospital demand was only 0.02%. Higher daily LTOWB demand resulted in more LTOWB shortages. Increasing the minimum LTOWB inventory threshold reduced LTOWB shortages without increasing the number of required additional RBC units. LTOWB wastage was minimal but was lower with longer LTOWB shelf life or manufacture of RBC units from unused LTOWB on Day 14.

CONCLUSION

Implementing an LTOWB program does not have a major impact on the blood collectors' needs for additional RBC units to meet hospital demands.

Hemolytic markers following the transfusion of uncrossmatched, cold-stored, low-titer, group O+ whole blood in civilian trauma patients

BACKGROUND

Low-titer group O whole blood (LTOWB) is increasingly being used in the civilian trauma setting, although there is a risk of hemolysis. This study evaluated the impact on hemolytic markers following the transfusion of 4 or more units of uncrossmatched LTOWB.

METHODS

Civilian adult trauma patients who received four or more units of leukoreduced group O+, low-titer (<50 anti-A and anti-B), platelet-replete uncrossmatched whole blood during their initial resuscitation and who survived for more than 24 hours after the transfusion were included in this retrospective study. Lactate dehydrogenase (LDH), total bilirubin, haptoglobin, potassium, and creatinine were evaluated on the day of LTOWB transfusion (Day 0) and the next 3 days. Blood product administration over the first 24 hours of admission was recorded.

RESULTS

There were 54 non-group O and 23 group O recipients of four or more LTOWB units. The median (interquartile range [IQR]) number of transfused LTOWB units was 4 (4-5) and 4 (4-4), respectively, the maximum number in both groups was eight. The non-group O patients received a median (IQR) volume of 1470 mL (1368-2052) of ABO-incompatible plasma. Comparing the non-group O to the group O recipients, there were no significant differences in the haptoglobin, LDH, total bilirubin, potassium, or creatinine concentrations at any of the time points. There were no reported transfusion reactions.

CONCLUSION

Receiving at least four LTOWB units was not associated with biochemical or clinical evidence of hemolysis.

How do you… decide which platelet bacterial risk mitigation strategy to select for your hospital-based transfusion service?

The United States Food and Drug Administration Final Guidance for Industry titled, "Bacterial Risk Control Strategies for Blood Collection Establishments and Transfusion Services to Enhance the Safety and Availability of Platelets for Transfusion" provides nine strategies for platelet bacterial risk mitigation. Even if it is assumed all strategies are comparable in terms of safety and efficacy, the decision of which to implement remains challenging. Some additional factors that warrant evaluation before selecting a strategy include the financial impact, process for implementation, logistics upon implementation, institutional acceptance by blood bank staff, administration and clinicians, and effect on platelet availability. To assist with this difficult choice, a panel of transfusion service physicians who have expertise on the topic and have already selected strategies for their transfusion services were recruited to provide varied perspectives. In addition, the use of a decision-making tool that objectively evaluates defined criteria for assessment of the nine strategies is described.

The evanescence and persistence of RBC alloantibodies in blood donors

BACKGROUND

Blood donors represent a healthy population, whose red blood cell (RBC) alloantibody persistence or evanescence kinetics may differ from those of immunocompromised patients. A better understanding of the biologic factors impacting antibody persistence is warranted, as the presence of alloantibodies may impact donor health and the fate of the donated blood product.

METHODS

Donor/donation data collected from four US blood centers from 2012 to 2016 as part of the Recipient Epidemiology and Donor Evaluation Study-III (REDS-III) were analyzed. Clinically significant antibodies from blood donors with more than one donation who underwent at least one follow-up antibody screen after the initial antibody identification were included. Of 632,378 blood donors, 481 (128 males and 353 females) fit inclusion criteria.

RESULTS

Antibody screens detected 562 alloantibodies, with 368 of 562 (65%) of antibodies being persistently detected and with 194 of 562 (35%) becoming evanescent. Factors associated with antibody persistence included antibody specificity, detection at the first donation, reported history of transfusion, and detection of multiple antibodies concurrently. Anti-D, C, and Fy^a were most likely to persist, while anti-M, Jk^a , and S were most frequently evanescent.

CONCLUSIONS

These data provide insight into variables impacting the duration of antibody detection, and they may also influence blood donor center policies regarding donor recruitment/acceptance.

Association of donor age, body mass index, hemoglobin, and smoking status with in-hospital mortality and length of stay among red blood cell-transfused recipients

BACKGROUND

Recent publications have reported conflicting findings regarding associations of blood donor demographics and mortality of transfused patients. We hypothesized that the analysis of additional donor characteristics and consideration of alternative outcomes might provide insight into these disparate results.

STUDY DESIGN AND METHODS

We analyzed data from a retrospective cohort of transfused patients from the Recipient Epidemiology and Donor Evaluation Study-III (REDS-III). We used stratified Cox regression models to estimate associations between blood donor characteristics and hospital mortality and posttransfusion length of stay among patients transfused red blood cell (RBC) units. Donor characteristics evaluated included age, body mass index, hemoglobin levels, and smoking status. The statistical analyses were adjusted for recipient factors, including total number of transfusions.

RESULTS

We studied 93,726 patients in 130,381 hospitalizations during which 428,461 RBC units were transfused. There were no associations between blood donor characteristics and hospital mortality. Receipt of RBC units from donors less than 20 years of age was associated with a shorter hospital length of stay (hazard ratio for discharge per transfused unit, 1.03; 95% confidence interval, 1.02-1.04; p < 0.001) but not for other donor characteristics.

CONCLUSION

We found no evidence of associations between blood donor factors and in-hospital mortality. Our finding of shorter hospital length of stay in patients transfused RBCs from younger donors is intriguing but requires confirmation. Future collaborations are needed to develop a framework of appropriate methodologic approaches to be used in linked analyses across large cohorts.

Improved quantitative detection of biotin-labeled red blood cells by flow cytometry

BACKGROUND

Biotin-labeled red blood cells (BioRBC) can be tracked after transfusion, providing a convenient and safe way to measure RBC survival in vivo. RBC survival is of interest for determining optimal blood storage conditions and for assessing the impact of genetic and biologic variants in blood donors on the survival of transfused RBCs. Here we present an improved, platform-independent assay for quantifying biotin on BioRBC. This approach is also useful for detecting BioRBC in peripheral blood samples as rare events.

STUDY DESIGN AND METHODS

We optimized the signal-to-noise ratio of the detecting reagent (phycoerythrin-conjugated streptavidin [SA-PE]) by determining the SA-PE concentration yielding the greatest separation index between BioRBC and unlabeled RBCs. We calibrated the fluorescence intensity measurements to molecules of equivalent soluble fluorochrome (MESF), a quantitative metric of fluorochrome binding and therefore of biotin bound per RBC. We then characterized the limit of blank and limit of quantification (LoQ) for BioRBC labeled at different densities.

RESULTS

Biotin-labeled RBCs at sulfo-NHS-biotin concentrations of 3 to 30 μg/mL (27-271 nmol/mL RBCs) ranged from approximately 32,000 to 200,000 MESF/RBC. The LoQ ranged from one in 274,000 to one in 649,000, depending on biotin-labeling density.

CONCLUSION

Increased sensitivity to detect BioRBC may facilitate tracking over longer periods and/or reduction of the BioRBC dose. Total RBC-bound biotin dose has been shown to correlate with the likelihood of developing antibodies to BioRBC. Lowering the dose of labeled cells may help avoid this eventuality.

Current good manufacturing practices-compliant manufacture and measurement of biotin-labeled red blood cells

BACKGROUND

Red blood cells (RBCs) can be labeled with N-hydroxysuccinimidobiotin (sulfo-NHS-biotin), which binds to cell surface proteins under aqueous conditions. Biotinylated RBCs can be safely infused and detected in peripheral blood samples using flow cytometry, using a fluorochrome-conjugated streptavidin (SA) detection reagent. Biotinylated RBCs have been used to track survival of transfused RBCs, and have applications in optimizing RBC storage and in understanding donor genetic, environmental and disease factors affecting RBC products.

METHODS

We have developed a closed-system, current good manufacturing practices (cGMP)-compliant procedure for biotinylation of RBCs and a quantitative flow cytometric assay to estimate the dose of cell-bound biotin delivered to the patient. Resulting products were characterized for variability, sterility, endotoxin, hemolysis, total dose of cell-bound biotin and stability.

RESULTS

The density of biotin-labeling increased as a log-linear function of sulfo-NHS-biotin-labeling concentration, with greater variability at lower concentrations. The upper estimates of biotin doses in the average product (mean RBC content = 5.55 × 10¹¹) were 9.8 and 73.0 µg for products labeled at 3 and 15 µg sulfo-NHS-biotin/mL of total reaction mixture (27 and 135 nmol/mL packed RBCs), respectively. All products were negative for bacterial and fungal growth at 14 days and were below the limit of endotoxin detection. Biotinylated RBCs were stable in vitro for up to 50 days after labeling.

DISCUSSION

We have validated a closed-system procedure for biotinylating RBCs for investigational use. A standard operating procedure is presented in sufficient detail for implementation in a cGMP-compliant cell-processing facility.

The Dead Sea needs salt water… massively bleeding patients need whole blood: The evolution of blood product resuscitation

Whole blood, that is blood that is not manufactured into its component red blood cells (RBC) plasma, and platelets (PLT) units, was the mainstay of transfusion for many years until it was discovered that the component parts of a blood donation could be stored under different conditions thereby optimizing the storage length of each product. The use of low anti-A and -B titer group O whole blood (LTOWB) has recently been rediscovered for use in massively bleeding trauma patients. Whole blood has several advantages over conventional component therapy for these patients, including simplifying the logistics of the resuscitation, being more concentrated than whole blood that is reconstituted from conventional components, and providing cold-stored PLTs, amongst other benefits. While randomized controlled trials to determine the efficacy of using LTOWB in the resuscitation of massively bleeding trauma patients are currently underway, retrospective data has shown that massively bleeding recipients of LTOWB with traumatic injury do not have worse outcomes compared to patients who received conventional components and, in some cases, recipients of LTOWB have more favourable outcomes. This paper will describe some of the advantages of using LTOWB and will discuss the emerging evidence for its use in massively bleeding patients.

Long-Term Outcomes Among Patients Discharged From the Hospital With Moderate Anemia: A Retrospective Cohort Study

BACKGROUND

Randomized clinical trial findings support decreased red blood cell (RBC) transfusion and short-term tolerance of in-hospital anemia. However, long-term outcomes related to changes in transfusion practice have not been described.

OBJECTIVE

To describe the prevalence of anemia at and after hospital discharge and associated morbidity and mortality events.

DESIGN

Retrospective cohort study.

SETTING

Integrated health care delivery system with 21 hospitals serving 4 million members.

PARTICIPANTS

445 371 surviving adults who had 801 261 hospitalizations between January 2010 and December 2014.

MEASUREMENTS

Hemoglobin levels and RBC transfusion, rehospitalization, and mortality events within 6 months of hospital discharge. Generalized estimating equations were used to examine trends over time, accounting for correlated observations and patient-level covariates.

RESULTS

From 2010 to 2014, the prevalence of moderate anemia (hemoglobin levels between 7 and 10 g/dL) at hospital discharge increased from 20% to 25% (P < 0.001) and RBC transfusion declined by 28% (39.8 to 28.5 RBC units per 1000 patients; P < 0.001). The proportion of patients whose moderate anemia had resolved within 6 months of hospital discharge decreased from 42% to 34% (P < 0.001), and RBC transfusion and rehospitalization within 6 months of hospital discharge decreased from 19% to 17% and 37% to 33%, respectively (P < 0.001 for both). During this period, the adjusted 6-month mortality rate decreased from 16.1% to 15.6% (P = 0.004) in patients with moderate anemia, in parallel with that of all others.

LIMITATION

Possible unmeasured confounding.

CONCLUSION

Anemia after hospitalization increased in parallel with decreased RBC transfusion. This increase was not accompanied by a rise in subsequent RBC use, rehospitalization, or mortality within 6 months of hospital discharge. Longitudinal analyses support the safety of practice recommendations to limit RBC transfusion and tolerate anemia during and after hospitalization.

PRIMARY FUNDING SOURCE

National Heart, Lung, and Blood Institute.

Mother-child histocompatibility and risk of rheumatoid arthritis and systemic lupus erythematosus among mothers

The study objective was to test the hypothesis that having histocompatible children increases the risk of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), possibly by contributing to the persistence of fetal cells acquired during pregnancy. We conducted a case control study using data from the UC San Francisco Mother Child Immunogenetic Study and studies at the Inova Translational Medicine Institute. We imputed human leukocyte antigen (HLA) alleles and minor histocompatibility antigens (mHags). We created a variable of exposure to histocompatible children. We estimated an average sequence similarity matching (SSM) score for each mother based on discordant mother-child alleles as a measure of histocompatibility. We used logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals. A total of 138 RA, 117 SLE, and 913 control mothers were analyzed. Increased risk of RA was associated with having any child compatible at HLA-B (OR 1.9; 1.2-3.1), DPB1 (OR 1.8; 1.2-2.6) or DQB1 (OR 1.8; 1.2-2.7). Compatibility at mHag ZAPHIR was associated with reduced risk of SLE among mothers carrying the HLA-restriction allele B*07:02 (n = 262; OR 0.4; 0.2-0.8). Our findings support the hypothesis that mother-child histocompatibility is associated with risk of RA and SLE.