Association of ABO-mismatched platelet transfusions with morbidity and mortality in cardiac surgery

Transfusion outcomes and clinical safety of ABO-nonidentical platelets transfusion: A systematic review and meta-analysis

BACKGROUND

ABO-nonidentical platelets transfusion has been frequently employed to address clinical platelets insufficiencies. The significance of ABO compatibility for platelets transfusion is not clearly defined. This study is aimed to explore the transfusion outcomes and clinical safety of ABO-nonidentical platelets transfusion.

STUDY DESIGN AND METHODS

A systematic articles search was performed for eligible studies published up to November 30, 2023 through the PubMed, Embase, Cochrane library, Chinese National Knowledge Infrastructure database, Wanfang database and SinMed. Meta-analysis Of Observational Studies in Epidemiology study guidelines for observational studies and Newcastle Ottawa bias scale were implemented to assess studies. Meta-analysis was performed using Manager 5.3. This study is registered with PROSPERO, number CRD42023417824.

RESULTS

A total of 11 retrospective cohort studies and 7 prospective cohort studies with a sample size of 104,359 platelets transfusions were included. There was significant difference in transfusion effectiveness between the ABO-identical and ABO-nonidentical platelets transfusions (RR 1.20, 95 % CI 1.11-1.38, P < 0.00001, I2 = 21 %), also the ABO-identical platelets transfusions showed more platelets increment than ABO-nonidentical ones, but it was not statistically significant (MD 0.34, 95 % CI - 0.01 to 0.70, P = 0.06, I2 = 0 %). Allergy and fever occurred more in ABO-nonidentical platelets transfusions in terms of adverse reactions (RR 0.63, 95 % CI 0.41-0.96, P = 0.03, I2 = 0 %; RR 0.59, 95 % CI 0.37-0.94, P = 0.03, I2 = 31 %). When it comes to the mortality, the ABO-identical platelets transfusions did not statistically improve survival in patients who received multiple platelets transfusions (RR 0.77, 95 % CI 0.72-0.83, P = 0.17, I2 = 38 %) and who only received less than 3 transfusions (RR 0.74, 95 % CI 0.52-1.06, P = 0.10, I2 = 47 %) compared with the ABO-nonidentical platelets transfusions.

CONCLUSION

In comparison to ABO-identical platelets transfusions, nonidentical platelets transfusions exhibited lower transfusion efficacy. However, the clinical safety between these two groups was similar, which indicated that ABO-nonidentical transfusions are acceptable, albeit inferior to ABO-identical ones.

Associations between ABO non-identical platelet transfusions and patient outcomes-A multicenter retrospective analysis

BACKGROUND

Due to platelet availability limitations, platelet units ABO mismatched to recipients are often transfused. However, since platelets express ABO antigens and are collected in plasma which may contain ABO isohemagglutinins, it remains controversial as to whether ABO non-identical platelet transfusions could potentially pose harm and/or have reduced efficacy.

STUDY DESIGN AND METHODS

The large 4-year publicly available Recipient Epidemiology and Donor Evaluation Study-III (REDS-III) database was used to investigate patient outcomes associated with ABO non-identical platelet transfusions. Outcomes included mortality, sepsis, and subsequent platelet transfusion requirements.

RESULTS

Following adjustment for possible confounding factors, no statistically significant association between ABO non-identical platelet transfusion and increased risk of mortality was observed in the overall cohort of 21,176 recipients. However, when analyzed by diagnostic category and recipient ABO group, associations with increased mortality for major mismatched transfusions were noted in two of eight subpopulations. Hematology/Oncology blood group A and B recipients (but not group O) showed a Hazard Ratio (HR) of 1.29 (95%CI: 1.03-1.62) and intracerebral hemorrhage group O recipients (but not groups A and B) showed a HR of 1.75 (95%CI: 1.10-2.80). Major mismatched transfusions were associated with increased odds of receiving additional platelet transfusion each post-transfusion day (through day 5) regardless of the recipient blood group.

DISCUSSION

We suggest that prospective studies are needed to determine if specific patient populations would benefit from receiving ABO identical platelet units. Our findings indicate that ABO-identical platelet products minimize patient exposure to additional platelet doses.

A Prospective Observational Study To Compare Transfusion Outcomes In Abo Identical Versus Abo Non-Identical Single Donor Platelet Concentrates: An Experience From A Tertiary Healthcare Center In India

ABO incompatible single donor platelet concentrates (SDPC) have a concern about unsatisfactory increments as well as possibility of hemolytic transfusion reaction. But from Indian population no study has commented on the clinical and laboratory outcome of ABO mismatched platelet transfusion. The aim of study was to compare transfusion outcomes in ABO identical versus ABO non-identical single donor platelet concentrates. In this prospective observational study, 400 SDPC transfusions among different patients were included. In group A (n = 200), ABO identical SDPC transfusions and in group B (n = 200) ABO non-identical SDPC transfusions were added. Corrective count increment (CCI), absolute count increment (ACI), percent platelet recovery (PPR) were calculated and incidents of hemolytic transfusion reactions were noted. In group A mean ± SD of ACI, CCI and PPR were as 30.78 ± 12.51, 15.10 ± 6.677, 39948.9 ± 20099.392. In group B, mean ± SD of ACI, CCI and PPR were - 25.4 ± 15.65, 12.509 ± 5.906, 33559.2 ± 22150.304. And when CCI, ACI, PPR were compared with group A and group B, statistically significant differences were noted (p <0.05). There was statistically significant difference in CCI, ACI and PPR in oncology patients and other prophylactic recipients except patients with dengue and other infectious disease. But there was no hemolytic transfusion reaction noted in any group. Our study clearly establish the potential benefits of ABO-identical PLT transfusion. It also points out that in emergency conditions or when there is a paucity in inventory, ABO non-identical SDPC transfusion may be lifesaving and clinically significant.

High titers of anti-A1 and anti-B antibodies among Peruvian group O platelet donors

Critical antibody titers have been described as factors associated with hemolysis in ABO plasma-incompatible platelet (PLT) transfusions. This study was carried out to describe the frequency of high-titers anti-A and antiB IgM and IgG antibodies in group O apheresis platelet donors, and to explore differences according to the donor characteristics. A cross-sectional study was carried out at the Blood Bank of a National Hospital in Peru from January to March 2019. IgM and IgG antibodies against A1 and B antigens were quantified in 339 platelet donors using the direct hemagglutination technique and the solid-phase adherence technique, respectively. For analysis purposes, two cut-off points; ≥128 and ≥64, were used to define a critical titer for IgM due to a lack of consensus. An IgG titer of ≥256 was also defined as critical. Of the donors, 22.1 % had critical IgM titers when the cut-off point was defined as ≥128. However, when the IgM cut-off was ≥64, the frequency of platelet donors with critical titers increased to 54.0 %. The frequency of donors with critical IgG titers was 23.5 %. Higher IgG titers were associated with female donors while higher IgM titers were negative associated with age. One in two or three platelet donors, depending on the cutoff point used to define a critical IgM titer, had at least one critical titer of anti-A or anti-B antibodies. Early identification of platelet donors with critical antibody titers could prevent passive transfusion of ABO antibodies to non-isogroup recipients.

Essential Role of Rho-Associated Kinase in ABO Immune Complex-Mediated Endothelial Barrier Disruption

ABO immune complexes (ABO-IC) formed by ABO-incompatible antigen-antibody interaction are associated with hemolysis and platelet destruction in patients transfused with ABO-nonidentical blood products. However, the effects of ABO-IC on endothelial cells (EC) are unclear. ABO-IC were formed in vitro from normal donor-derived plasma and serum. Human pulmonary artery EC (HPAEC) were cultured and treated with media, ABO-identical and –non-identical plasma, and ABO-IC. EC barrier integrity was evaluated using transendothelial electrical resistance (TEER), scanning electron microscopy (SEM), vascular endothelial (VE)-cadherin and phalloidin staining, and Rho-associated Kinase (ROCK) inhibitor treatment. TEER revealed significant/irreversible barrier disruption within 1–2 h of exposure to ABO non-identical plasma and ABO-IC; this occurred independently of EC ABO type. Treatment with ABO-IC resulted in decreased VE-cadherin staining and increased phalloidin staining in a time-dependent manner, suggesting that the resultant increased EC barrier permeability is secondary to actin stress fiber formation and loss of cell surface VE-cadherin. Inhibition of ROCK was effective in protecting against IC-induced barrier disruption even two hours after ABO-IC exposure. ABO-IC causes increased EC barrier permeability by decreasing cell surface VE-cadherin and promoting stress fiber formation, which is preventable by inhibiting ROCK activation to protect against EC contraction and gap formation.

Impacts of ABO-incompatible platelet transfusions on platelet recovery and outcomes after intracerebral hemorrhage

Acute platelet transfusion after intracerebral hemorrhage (ICH) given in efforts to reverse antiplatelet medication effects and prevent ongoing bleeding does not appear to improve outcome and may be associated with harm. Although the underlying mechanisms are unclear, the influence of ABO-incompatible platelet transfusions on ICH outcomes has not been investigated. We hypothesized that patients with ICH who receive ABO-incompatible platelet transfusions would have worse platelet recovery (using absolute count increment [ACI]) and neurological outcomes (mortality and poor modified Rankin Scale [mRS 4-6]) than those receiving ABO-compatible transfusions. In a single-center cohort of consecutively admitted patients with ICH, we identified 125 patients receiving acute platelet transfusions, of whom 47 (38%) received an ABO-incompatible transfusion. Using quantile regression, we identified an association of ABO-incompatible platelet transfusion with lower platelet recovery (ACI, 2 × 103cells per μL vs 15 × 103cells per μL; adjusted coefficient β, -19; 95% confidence interval [CI], -35.55 to -4.44; P = .01). ABO-incompatible platelet transfusion was also associated with increased odds of mortality (adjusted odds ratio [OR], 2.59; 95% CI, 1.00-6.73; P = .05) and poor mRS (adjusted OR, 3.61; 95% CI, 0.97-13.42; P = .06); however, these estimates were imprecise. Together, these findings suggest the importance of ABO compatibility for platelet transfusions for ICH, but further investigation into the mechanism(s) underlying these observations is required.

Transfusion of ABO non-identical platelets increases the severity of trauma patients at ICU admission

BACKGROUND

Transfusion of ABO-compatible non-identical platelets (PTLs), fresh plasma (FP) and red blood cells (RBCs) has been associated with increased morbidity and mortality of recipients. Trauma victims are frequently exposed to ABO non-identical products, given the need for emergency transfusions. Our goal was to evaluate the impact of the transfusion of ABO non-identical blood products on the severity and all-cause 30-day mortality of trauma patients.

METHODS

This was a retrospective single-center cohort, which included trauma patients who received emergency transfusions in the first 24 h of hospitalization. Patients were divided in two groups according to the use of <3 or ≥3 ABO non-identical blood products. The patient severity, measured by the Acute Physiology and Chronic Health Evaluation (APACHEII) score at ICU admission, and the 30-day mortality were compared between groups.

RESULTS

Two hundred and sixteen trauma patients were enrolled. Of these, 21.3% received ≥3 ABO non-identical blood products (RBCs, PLTs and FP or cryoprecipitate). The transfusion of ≥3 ABO non-identical blood products in the first 24 h of hospitalization was independently associated with a higher APACHEII score at ICU admission (OR = 3.28 and CI95% = 1.48-7.16). Transfusion of at least one unit of ABO non-identical PTLs was also associated with severity (OR = 10.89 and CI95% = 3.38-38.49). Transfusion of ABO non-identical blood products was not associated with a higher 30-day mortality in the studied cohort.

CONCLUSION

The transfusion of ABO non-identical blood products and, especially, of ABO non-identical PLTs may be associated with the greater severity of trauma patients at ICU admission. The transfusion of ABO non-identical blood products in the trauma setting is not without risks.

Indications for red cell transfusions in pediatric patients

Red cell transfusions are amongst the most common therapeutic procedures in seriously ill children, particularly in the inpatient setting. This is despite the fact that there is no evidence base for most clinical settings, with the exception of patients with hemoglobinopathies, particularly thalassemia and sickle cell anemia. Obviously exsanguinating hemorrhage and life threatening anemia are urgent indications for which no other therapeutic approach is currently available. Most transfusions are, however, given prophylactically to prevent the complications of hypoxia or hemodynamic stability, based upon expert opinion and a faith in the oxygen carrying capacity and beneficial hemodynamic properties of transfused red cells. The question confronting current day pediatric practice is to what extent transfused red cells prevent adverse events, other than in thalassemia and sickle cell anemia, as opposed to causing them. Do transfusions of red cells prevent organ failure, stroke, etc. or not? There is epidemiologic evidence in the adult randomized trial literature that liberal red cell transfusion likely causes more such adverse events than it prevents. The relevance of such studies to children, particularly neonates, is uncertain. Randomized trials in critically ill neonates have yielded little to no evidence that liberal red cell transfusion is beneficial, but the data are not definitive. In critically ill older children the data suggest there is no benefit to liberal red cell transfusion, but the indications for red cell transfusion are uncertain. Most practitioners would agree that combining laboratory data such hemoglobin/hematocrit with clinical indications for transfusions (evidence of end organ hypoxia such as tachycardia, shortness of breath, etc.) is the only viable strategy at present, until more definitive randomized trial data are available.

Potential impact of complement regulator deficiencies on hemolytic reactions due to minor ABO-mismatched transfusions

Minor ABO-mismatched transfusions are a common occurrence, although infrequent transfusion reactions occur. We sought to investigate the regulation of complement C3 activation induced by anti-A. In vitro complement C3 activation was observed with 10 of 30 group O samples and correlated with immunoglobulin M (IgM) anti-A titers. We developed an in vitro paroxysmal nocturnal hemoglobinuria (PNH) model of hemolysis in which group A1 red blood cells (RBCs) were chemically treated with 2-aminoethylisothiouronium (AET) to alter regulators of complement C3 activation. Intravascular hemolysis was simulated by incubating an IgG nonhemolytic group O plasma (titer = 32) with A1 RBCs. IgG was detected on the RBCs, but hemolysis was observed with AET-treated RBCs only. When treated and untreated RBCs were tested together (1:4), we determined that the failure to observe C3b/d deposition on RBCs was due to the complete hemolysis of the AET-treated minor RBC population. A group O patient with a 9% CD59-deficient PNH clone was sensitized with an IgM anti-I. Hemolysis, with a weak positive direct antiglobulin test (DAT) resulting from C3b/d, was observed after incubation with fresh AB serum. Flow cytometry showed an 86% reduction of the PNH clone. Our work indicates that the transfusion of minor ABO-mismatched plasma could cause hemolysis with a negative DAT C3b/d. We propose that the presence of a PNH clone is 1 possible cause of unexplained anemia for recipients of ABO-mismatched product. This work suggests that other acquired or inherited defects of decay-accelerating factor and membrane inhibitor of reactive lysis could be responsible for infrequent but clinically important hemolysis after ABO-mismatched transfusions.

Recent Advances in Preventing Adverse Reactions to Transfusion

The spectrum of adverse reactions to blood product transfusion ranges from a benign clinical course to serious morbidity and mortality.  There have been many advances in technologies and transfusion strategies to decrease the risk of adverse reactions. Our aim is to address a few of the advancements in increasing the safety of the blood supply, specifically pathogen reduction technologies, bacterial contamination risk reduction, and transfusion associated acute lung injury risk mitigation strategies.

Current trends in platelet transfusions practice: The role of ABO-RhD and human leukocyte antigen incompatibility

Platelet transfusions have contributed to the revolutionary modern treatment of hypoproliferative thrombocytopenia. Despite the long-term application of platelet transfusion in therapeutics, all aspects of their optimal use (i.e., in cases of ABO and/or Rh (D incompatibility) have not been definitively determined yet. We reviewed the available data on transfusion practices and outcome in ABO and RhD incompatibility and platelet refractoriness due to anti-human leukocyte antigen (HLA) antibodies. Transfusion of platelets with major ABO-incompatibility is related to reduced posttransfusion platelet (PLT) count increments, compared to ABO-identical and minor, but still are equally effective in preventing clinical bleeding. ABO-minor incompatible transfusions pose the risk of an acute hemolytic reaction of the recipient that is not always related to high anti-A, B donor titers. ABO-identical PLT transfusion seems to be the most effective and safest therapeutic strategy. Exclusive ABO-identical platelet transfusion policy could be feasible, but alternative approaches could facilitate platelet inventory management. Transfusion of platelets from RhD positive donors to RhD negative patients is considered to be effective and safe though is associated with low rate of anti-D alloimmunization due to contaminating red blood cells. The prevention of D alloimmunization is recommended only for women of childbearing age. HLA alloimmunization is a major cause of platelet refractoriness. Managing patients with refractoriness with cross-matched or HLA-matched platelets is the current practice although data are still lacking for the efficacy of this practice in terms of clinical outcome. Leukoreduction contributes to the reduction of both HLA and anti-D alloimmunization.

2015 proceedings of the National Heart, Lung, and Blood Institute's State of the Science in Transfusion Medicine symposium

On March 25 and 26, 2015, the National Heart, Lung, and Blood Institute sponsored a meeting on the State of the Science in Transfusion Medicine on the National Institutes of Health (NIH) campus in Bethesda, Maryland, which was attended by a diverse group of 330 registrants. The meeting's goal was to identify important research questions that could be answered in the next 5 to 10 years and which would have the potential to transform the clinical practice of transfusion medicine. These questions could be addressed by basic, translational, and/or clinical research studies and were focused on four areas: the three "classical" transfusion products (i.e., red blood cells, platelets, and plasma) and blood donor issues. Before the meeting, four working groups, one for each area, prepared five major questions for discussion along with a list of five to 10 additional questions for consideration. At the meeting itself, all of these questions, and others, were discussed in keynote lectures, small-group breakout sessions, and large-group sessions with open discourse involving all meeting attendees. In addition to the final lists of questions, provided herein, the meeting attendees identified multiple overarching, cross-cutting themes that addressed issues common to all four areas; the latter are also provided. It is anticipated that addressing these scientific priorities, with careful attention to the overarching themes, will inform funding priorities developed by the NIH and provide a solid research platform for transforming the future practice of transfusion medicine.

The Blood Group A Genotype Determines the Level of Expression of the Blood Group A on Platelets But Not the Anti-B Isotiter

BACKGROUND

The extent of expression of the blood group A on platelets is controversial. Further, the relation between platelets' blood group A expression and the titers of isoagglutinins has not been thoroughly investigated, so far.

METHODS

We evaluated the relation between the genotype with platelets' blood group A and H expression estimated by flow cytometry and the titers of isoagglutinins.

RESULTS

The A expression varied between genotypes and within genotypes. However, the expression in A1 was stronger than in all other genotypes (p < 0.0001). An overlap of expression levels was apparent between homozygous A1A1 and heterozygous A1 individuals. Still, The A1A1 genotype is associated with a particularly high antigen expression (p = 0.009). Platelets' A expression in A2 versus blood group O donors was also significant (p = 0.007), but there was again an overlap of expression. The secretor status had only little influence on the expression (p = 0.18). Also, isoagglutinin titers were not associated with genotypes.

CONCLUSION

To distinguish between A1 and A2 donors may reduce incompatible platelet transfusions and therefore be favorable on platelet transfusion increment. Clinical data are needed to support this notion.

Platelet transfusion - the new immunology of an old therapy

Platelet transfusion has been a vital therapeutic approach in patients with hematologic malignancies for close to half a century. Randomized trials show that prophylactic platelet transfusions mitigate bleeding in patients with acute myeloid leukemia. However, even with prophylactic transfusions, as many as 75% of patients, experience hemorrhage. While platelet transfusion efficacy is modest, questions and concerns have arisen about the risks of platelet transfusion therapy. The acknowledged serious risks of platelet transfusion include viral transmission, bacterial sepsis, and acute lung injury. Less serious adverse effects include allergic and non-hemolytic febrile reactions. Rare hemolytic reactions have occurred due to a common policy of transfusing without regard to ABO type. In the last decade or so, new concerns have arisen; platelet-derived lipids are implicated in transfusion-related acute lung injury after transfusion. With the recognition that platelets are immune cells came the discoveries that supernatant IL-6, IL-27 sCD40L, and OX40L are closely linked to febrile reactions and sCD40L with acute lung injury. Platelet transfusions are pro-inflammatory, and may be pro-thrombotic. Anti-A and anti-B can bind to incompatible recipient or donor platelets and soluble antigens, impair hemostasis and thus increase bleeding. Finally, stored platelet supernatants contain biological mediators such as VEGF and TGF-β1 that may compromise the host versus tumor response. This is particularly of concern in patients receiving many platelet transfusions, as for acute leukemia. New evidence suggests that removing stored supernatant will improve clinical outcomes. This new view of platelets as pro-inflammatory and immunomodulatory agents suggests that innovative approaches to improving platelet storage and pre-transfusion manipulations to reduce toxicity could substantially improve the efficacy and safety of this long-employed therapy.

Transfusion of ABO non-identical platelets does not influence the clinical outcome of patients undergoing autologous haematopoietic stem cell transplantation

BACKGROUND

There are ABO antigens on the surface of platelets, but whether ABO compatible platelets are necessary for transfusions is a matter of ongoing debate. We retrospectively reviewed the ABO matching of platelet transfusions in a subset of patients undergoing autologous haematopoietic progenitor cell transplantation during a 14-year period. Our aim was to analyse the characteristics and outcomes of patients who received platelet transfusions that were or were not ABO identical.

MATERIAL AND METHODS

We analysed 529 consecutive patients with various haematological and non-haematological diseases who underwent 553 autologous progenitor stem cell transplants at the University Hospital la Fe between January 2000 and December 2013. We retrospectively analysed and compared transfusion and clinical outcomes of patients according to the ABO match of the platelet transfusions received. The period analysed was the time from transplantation until discharge.

RESULTS

The patients received a total of 2,772 platelet concentrates, of which 2,053 (74.0%) were ABO identical and 719 (26.0%) ABO non-identical; of these latter 309 were compatible and 410 incompatible with the patients' plasma. Considering all transplants, 36 (6.5%) did not require any platelet transfusions, while in 246 (44.5%) cases, the patients were exclusively transfused with ABO identical platelets and in 47 (8.5%) cases they received only ABO non-identical platelet transfusions. The group of patients who received both ABO identical and ABO non-identical platelet transfusions had higher transfusion needs and worse clinical outcomes compared to patients who received only ABO identical or ABO non-identical platelets.

DISCUSSION

In our hospital, patients undergoing autologous haematopoietic stem cell transplantation who received ABO identical or ABO non-identical platelet transfusions had similar transfusion and clinical outcomes. The isolated fact of receiving ABO non-identical platelets did not influence morbidity or survival.

Comparison of two platelet transfusion strategies to minimize ABO-nonidentical transfusion, outdating, and shortages using a computer-simulated "virtual blood bank"

BACKGROUND

Transfusion of ABO-incompatible platelets (PLTs) is associated with reduced PLT recovery and a risk of transfusion reactions. However, a policy of transfusing only ABO-identical PLTs may increase wastage due to product outdating. A prospective study attempting to compare the effects of different ABO compatibility strategies could be costly and disruptive to a blood bank's operations.

STUDY DESIGN AND METHODS

We designed a "virtual blood bank," a stochastic computer program that models the stocking and release of products to meet demand for PLT transfusion in a simulated hospital population. ABO-nonidentical transfusions (ABOni), outdates, and inventory shortages were recorded and compared under two different transfusion strategies: ABO-First, a strategy that prioritizes transfusion of ABO-identical PLTs, and Age-First, a strategy that minimizes outdating by transfusing products closest to expiration.

RESULTS

The ABO-First strategy resulted in fewer ABOni but more outdates than the Age-First strategy. Under conditions that mimic a large hospital blood bank, the ABO-First strategy was more cost-effective overall than the Age-First strategy if avoiding an ABOni is valued at more than $19 to $26. For a small blood bank, the ABO-First strategy was more cost-effective if avoiding an ABOni is valued at more than $104 to $123.

CONCLUSION

Based on a virtual blood bank computer simulation, the cost of avoiding an ABOni using the ABO-First strategy varies greatly by size of institution. Individual blood banks must carefully consider these management strategies to determine the most cost-effective solution.

Platelet transfusion - the art and science of compromise

SUMMARY

Many modern therapies depend on platelet (PLT) transfusion support. PLTs have a 4- to 7-day shelf life and are frequently in short supply. In order to optimize the inventory PLTs are often transfused to adults without regard for ABO compatibility. Hemolytic reactions are infrequent despite the presence of 'high titer' anti-A and anti-B antibodies in some of the units. Despite the low risk for hemolysis, some centers provide only ABO identical PLTs to their recipients; this practice might have other beneficial outcomes that remain to be proven. Strategies to mitigate the risk of hemolysis and the clinical and laboratory outcomes following ABO-matched and mismatched transfusions will be discussed. Although the PLTs themselves do not carry the D antigen, a small number of RBCs are also transfused with every PLT dose. The quantity of RBCs varies by the type of PLT preparation, and even a small quantity of D+ RBCs can alloimmunize a susceptible D- host. Thus PLT units are labeled as D+/-, and most transfusion services try to prevent the transfusion of D+ PLTs to D- females of childbearing age. A similar policy for patients with hematological diseases is controversial, and the elements and mechanisms of anti-D alloimmunization will be discussed.

Transfusion medicine problems and solutions for the pediatric hematologist/oncologist

Blood component transfusion is an integral part of the care of children with oncologic and hematologic conditions. The complexity of transfusion medicine may however lead to challenges for pediatric hematologists/oncologists. In this review, three commonly encountered areas of transfusion medicine are explored. The approach to the investigation and management of suspected platelet refractoriness is reviewed. The unique transfusion related challenges encountered by children undergoing stem cell transplantation are also discussed. Finally, issues arising out of the care of children with hemoglobinopathies are explored, with an emphasis on the incidence of allo- and autoimmunization.

Alterations of platelet function and clot formation kinetics after in vitro exposure to anti-A and -B

BACKGROUND

ABO-mismatched platelets (PLTs) are commonly transfused despite reported complications. We hypothesized that because PLTs possess A and B antigens on their surface, ABO-mismatched transfused or recipient PLTs could become activated and/or dysfunctional after exposure to anti-A or -B in the transfused or recipient plasma. We present here in vitro modeling data on the functional effects of exposure of PLTs to ABO antibodies.

STUDY DESIGN AND METHODS

PLT functions of normal PLTs of all ABO types were assessed before and after incubation with normal saline, ABO-identical plasma samples, or O plasma samples with varying titers of anti-A and anti-B (anti-A/B). Assays used for this assessment include PLT aggregation, clot kinetics, thrombin generation, PLT cytoskeletal function, and mediator release.

RESULTS

Exposure of antigen-bearing PLTs to O plasma with moderate to high titers of anti-A/B significantly inhibits aggregation, prolongs PFA-100 epinephrine closure time, disrupts clot formation kinetics, accelerates thrombin generation, reduces total thrombin production, alters PLT cytoskeletal function, and influences proinflammatory and prothrombotic mediator release.

CONCLUSIONS

Our findings demonstrate a wide range of effects that anti-A/B have on PLT function, clot formation, thrombin generation, PLT cytoskeletal function, and mediator release. These data provide potential explanations for clinical observations of increased red blood cell utilization in trauma and surgical patients receiving ABO-nonidentical blood products. Impaired hemostasis caused by anti-A/B interacting with A and B antigens on PLTs, soluble proteins, and perhaps even endothelial cells is a potential contributing factor to hemorrhage in patients receiving larger volumes of ABO-nonidentical transfusions.

Providing ABO-identical platelets and cryoprecipitate to (almost) all patients: approach, logistics, and associated decreases in transfusion reaction and red blood cell alloimmunization incidence

BACKGROUND

There are multiple benefits to transfusing only ABO-identical blood components. Historically our institution routinely transfused ABO-nonidentical platelets (PLTs) and cryoprecipitate to surgical patients. In April 2005, we implemented a policy of transfusing only ABO-identical components whenever feasible, regardless of outdating or logistic considerations.

STUDY DESIGN AND METHODS

Technical staff closely monitored product usage and adjusted blood center orders based on recent utilization and planned transfusions. When unable to provide ABO-identical PLTs, ABO-compatible PLTs were washed to remove incompatible plasma. Data on outdating were collected for 18 months before and after implementation. We compared transfusion reaction and red blood cell (RBC) alloimmunization incidence for 4 years preceding (2001-2004) and subsequent (2006-2009) to implementation.

RESULTS

In the year after implementation, only 11 of 410 surgical patients received ABO-nonidentical PLTs (2.7%). There was a 5.6% increase in outdating of PLTs. Transfusing ABO-identical components was associated with significant reductions in febrile (-46%; 8.0 to 4.3 per 10,000 components; p < 0.0001) and allergic transfusion reactions (-23%; from 7.0 to 5.4 per 10,000 components; p = 0.025). A progressive reduction in de novo RBC alloimmunization incidence also occurred (-50% by 2009; p = 0.03).

CONCLUSIONS

Providing ABO-identical PLTs to almost all patients was feasible in our setting by changing ordering and inventorying procedures and making the ABO-identical policy a staff priority. Unexpected and striking reductions in febrile and allergic reactions and RBC alloimmunization were observed, of uncertain causal relationship to this ABO policy change, which will require further study.

An association of ABO non-identical platelet and cryoprecipitate transfusions with altered red cell transfusion needs in surgical patients

BACKGROUND

Transfusion of ABO non-identical plasma, platelets and cryoprecipitate is routine practice even though adverse effects can occur.

METHODS AND MATERIALS

Our hospital changed transfusion practice in 2005 and adopted a policy of providing ABO-identical blood components to all patients when feasible. We retrospectively compared the transfusion requirements, length of stay and in-hospital mortality in relation to ABO blood group in surgical patients who received platelet transfusions before and after this change to determine whether it resulted in any benefit.

RESULTS

Prior to the change in practice, both group B and AB patients received more ABO non-identical platelet transfusion (P=0·0004), required significantly greater numbers of red cell transfusions (P=0·04) and had 50% longer hospital stays (P=0·039) than group O and A patients. Following the policy change, there was a trend for fewer red cell transfusions (P=0·17) and length of stay in group B and AB patients than group O or A patients. Overall, the mortality rate per red cell transfusion decreased from 15·2 per 1000 to 11·0 per 1000 (P=0·013).

CONCLUSIONS

These results, in the context of previous findings, suggest that providing ABO-identical platelets and cryoprecipitate might be associated with reduction in transfusion requirements and improve outcomes in surgical patients.

Platelet Activation Following Exposure to Anti-ABO Antibodies-An In Vitro Study

Since platelets possess A and B antigen, mismatched ABO platelets could, theoretically, become activated or hypofunctional by exposure to anti-A or anti-B antibodies found in transfused or recipient plasma. Following normal baseline platelet aggregation to adenosine diphosphate (ADP), platelets from normal donors of different blood types were incubated at 37°C for 10 minutes with 50μl of normal saline (NS), O plasma, or AB plasma. Aggregation was then induced with ADP. No significant changes from baseline were seen in platelet aggregation studies following incubation with NS. However, platelet aggregations of type A and type B platelets were significantly inhibited when incubated with O plasma (mean of 41 and 22%, respectively). Our findings indicate that mediators in group O plasma, very likely anti-A and anti-B antibodies, cause impaired platelet aggregation of ABO non-identical platelets.

Lack of significant de novo HLA allosensitization in ventricular assist device recipients transfused with leukoreduced, ABO identical blood products

Ventricular assist devices provide support for a failing heart and often serve as a bridge to transplantation. The use of these devices has also been associated with allosensitization to HLA antigens because of transfusion of blood products. Our program established a protocol mandating the use of leukoreduced, irradiated and ABO identical products, including platelets, in patients receiving initial implantations of VADs as a bridge to transplantation. Recipients were tested for anti-HLA antibodies before VAD implantation and monthly post-implantation by cytotoxicity and solid phase assays. We observed minimal de novo anti-HLA sensitization (<10%) in this population of 55 patients, each receiving a mean of 90 blood components, using this approach. No patient developed broad sensitization (PRA>50%). In conclusion, The use of leukoreduced, irradiated, ABO identical blood products abrogates broad allosensitization in this highly transfused population.

Post-transfusion mortality among recipients of ABO-compatible but non-identical plasma

BACKGROUND AND OBJECTIVES

The consequences of ABO-compatible non-identical plasma for patient outcome have not been studied in randomized clinical trials or large cohort studies and use varies widely in the absence of evidence-based policies. We investigated if transfusion with compatible instead of identical plasma confers any short-term survival disadvantage on the recipients.

MATERIALS AND METHODS

The cohort of all 86 082 Swedish patients who received their first plasma transfusion between 1990 and 2002 was followed for 14 days and the risk of death in patients exposed to compatible non-identical plasma compared to recipients of only identical plasma.

RESULTS

After adjustment for potential confounding factors, there was an increased mortality associated with exposure to ABO-compatible non-identical plasma, with the excess risk mostly confined to those receiving 5 or more units (relative risk, 1.15; 95% confidence interval, 1.02-1.29). Stratification by blood group indicated higher risks in group O recipients, especially when the compatible plasma was from a group AB donor.

CONCLUSIONS

This study suggests that ABO-compatible non-identical plasma is less safe than identical plasma. Subanalyses by blood group suggest a role for circulating immune complexes. Our findings may have policy implications for improving transfusion safety.

Efficacy and Adverse Events of Platelet Transfusion Product-Specific Differences

SUMMARY: TWO PREPARATIONS ARE AVAILABLE FOR PLATELET TRANSFUSION: single-donor apheresis platelet concentrates (APC) and pooled platelet concentrates (PPC) prepared from 4-6 whole blood units. Clear advantages of APC over PPC are a markedly reduced donor exposure of recipients, and easier logistics when attempting a complete supply with ABO-identical and Rh-compatible platelet concentrates. Regulations should aim at complete ABO-identical platelet transfusions because major and minor ABO-incompatible platelet transfusions are probably associated with significantly increased morbidity and mortality. The main advantage of PPC is lower costs. Preparation of PPC is however inevitably accompanied by substantial wastage of plasma and red cells. Only major supraregional blood transfusion centers can guarantee full-coverage supply with ABO-identical and Rh-compatible PPC. Whether APC are more effective than PPC and associated with fewer septic platelet transfusion reactions as shown in some but not all studies, has to be examined in future prospective controlled trials.

Transfusion of platelets containing ABO-incompatible plasma: a survey of 3156 North American laboratories

CONTEXT

Hemolytic transfusion reactions due to platelet transfusions containing ABO-incompatible plasma (ie, group O platelets into a non-group O patient) have been reported in the literature. However, limited data describe the extent to which transfusion services manage such platelet transfusions or the methods used to limit the risk of such reactions.

OBJECTIVE

To determine transfusion services' current practices regarding the use of platelets containing ABO-incompatible plasma.

DESIGN

In a College of American Pathologists' Transfusion Medicine Proficiency Testing Survey, supplemental questions asked participants whether a policy existed for the use of platelets containing ABO-incompatible plasma and, if a policy existed, what elements were part of the policy.

RESULTS

Of 3156 laboratories that transfused platelets, 3152 responded to the question of whether they had a policy. Of these respondents, 83% (n = 2623) had a policy. One or more elements were reported for transfusions in adults: only ABO-compatible plasma products (n = 1363); only ABO-compatible plasma and platelet products (n = 679); notification of medical director (n = 646); notification of ordering physician (n = 637); volume limit of ABO-incompatible plasma allowed (n = 255); volume-reduction of ABO-incompatible products (n = 168); screening for critical titer of anti-A or anti-B (n = 53). A total of 529 laboratories indicated that they did not have a policy.

CONCLUSIONS

A majority of laboratories have a policy, but most do not include a method to limit the risk of hemolysis if platelets containing ABO-incompatible plasma must be transfused. When such platelets are used, there does not appear to be consensus on a specific method to minimize the transfusion of anti-A or anti-B.

What would Karl Landsteiner do? The ABO blood group and stem cell transplantation

ABO blood group antigens, of great importance in transplantation and transfusion, are present on virtually all cells, as well as in soluble form in plasma and body fluids. Naturally occurring plasma IgM and IgG antibodies against these antigens are ubiquitous. Nonetheless, the ABO blood group system is widely ignored by many transfusion services, except for purposes of red cell transfusion. We implemented a policy of transfusing only ABO identical platelets and red cells in patients undergoing stem cell transplantation or treatment for hematologic malignancies. Major bleeding episodes have occurred in about 5% of patients undergoing induction therapy for acute leukemia as compared with 15-20% in the literature. Overall survival times appear to be superior to that in historical cohorts. In 2002-2004, treatment-related mortality at 100 days in our Blood and Marrow Transplant Unit was 0.7% for autologous transplants (n=148), 13% for sibling allogeneic transplants (n=110), and 24% (n=62) for matched unrelated allogeneic transplants, suggesting that our approach is safe. We speculate that more rigorous efforts on the part of transfusion services to provide ABO identical blood components, and to remove incompatible supernatant plasma, when necessary, might yield reduced morbidity and mortality in patients undergoing stem cell transplantation.

A randomized trial of washed red blood cell and platelet transfusions in adult acute leukemia [ISRCTN76536440]

BACKGROUND: Platelet transfusion is universally employed in acute leukemia. Platelet concentrate supernatants contain high concentrations of biologic mediators that might impair immunity. We investigated whether washed platelet and red cell transfusions could improve clinical outcomes in adult patients with acute leukemia. METHODS: A pilot randomized trial of washed, leukoreduced ABO identical transfusions versus leukoreduced ABO identical transfusions was conducted in 43 adult patients with acute myeloid or lymphoid leukemia during 1991-94. Primary endpoints to be evaluated were platelet transfusion refractoriness, infectious and bleeding complications and overall survival. RESULTS: There were no significant differences in infectious or major bleeding complications and only one patient required HLA matched platelet transfusions. Minor bleeding was more frequent in the washed, leukoreduced arm of the study. Confirmed transfusion reactions were more frequent in the leukoreduced arm of the study. Overall survival was superior in the washed arm of the study (40% versus 22% at 5 years), but this difference was not statistically significant (p = 0.36). A planned subset analysis of those Collapse

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Affiliation(s)

Neil Blumberg Department of Pathology & Laboratory Medicine (Transfusion Medicine Unit), University of Rochester Medical Center, Box 608, Rochester, NY 14642 USA
Joanna M Heal Department of Medicine (Hematology-Oncology Division), University of Rochester Medical Center, Box 608, Rochester, NY 14642 USA
Jacob M Rowe Department of Medicine (Hematology-Oncology Division), University of Rochester Medical Center, Box 608, Rochester, NY 14642 USA Dept. of Hematology and BMT, Rambam Medical Center, Haifa 31096 Israel

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PLTs of Blood Group A1donors express increased surface A antigen owing to apheresis and prolonged storage

BACKGROUND

In contrast to RBC transfusion, where ABO mismatch is potentially lethal, immunologic ABO matching has been considered less critical for PLTs. Nonetheless, PLTs bear ABO blood group antigens, some of them expressing very high levels.

STUDY DESIGN AND METHODS

The expression of A antigen was investigated by flow cytometry on resting and stimulated human PLTs of 100 A and 10 O group donors, as well as on 17 PLT concentrates (PCs) after apheresis and daily during a 6-day storage, to determine possible changes in expression of A antigen on PLT surface.

RESULTS

Considerable variation of A antigen expression on PLT surface of A1 group individuals was observed; A2 group PLTs could not be distinguished from O group PLTs. The variability of A antigen on A group PLTs also became evident on investigating PLT lysates by ELISA. A1 group PCs showed a significant increase of A antigen expression on their surface owing to apheresis (p = 0.001) and to storage (p = 0.0091).

CONCLUSION

Apheresis and prolonged storage of A1 group PCs independently led to overexpression of A antigen on the PLT surface. This may make such PCs more susceptible to destruction by anti-A of O or B group recipients.

Transfusion of ABO-nonidentical platelets is not associated with adverse clinical outcomes in cardiovascular surgery patients

BACKGROUND

Current blood transfusion standards in Canada and the United States permit transfusion of ABO-nonidentical platelets when ABO-identical platelets are not available. This practice increases the availability of platelets, a component in chronic shortage in Ontario, Canada because of the 5-day shelf-life. The impact of transfusing ABO-nonidentical platelets on patient outcomes is unknown. STUDY DESIGN AND METHODS. A retrospective review of 1721 patients who had cardiovascular surgery between November 1989 and December 1999 and who had also received a platelet transfusion perioperatively was conducted. The impact of platelet and plasma incompatibility on clinical outcomes was analyzed.

RESULTS

The analysis included 1691 patients who were divided into two groups according to the compatibility of the first platelet transfusion received: ABO-identical platelet transfusion (n = 1008) and ABO-nonidentical platelet transfusion (n = 683). The only difference in baseline characteristics between the two groups was that there were more urgent cases in the ABO-identical platelet transfusion group (p = 0.04). There were no significant differences in mortality at 30 days (10% for both groups, p = NS) or in postoperative length of stay (median, 7.0 days for both groups, p = NS). No significant differences were found with respect to the use of blood components, indices of bleeding, incidence of infection, or platelet CCIs.

CONCLUSION

Transfusion of ABO-nonidentical platelets in patients undergoing cardiovascular surgery is not associated with an adverse impact on patient outcome.