A retrospective analysis of haemolytic reactions to intravenous immunoglobulin using data from the Transfusion-Transmitted Injuries Surveillance System (Ontario).

BACKGROUND AND OBJECTIVES: Haemolysis can occur following intravenous immunoglobulin (IVIG) infusion. Haemovigilance data were analysed using a novel approach for including two control groups with no haemolysis to IVIG. Objectives included a summary of all reactions to IVIG, rate estimates and analysis of haemolytic reactions including risk factors. MATERIALS AND METHODS: Canadian haemovigilance data from Ontario (2013-2021), IVIG distribution and transfusion data from the blood supplier, and data from a large local transfusion registry were used. An 'other-reactions' control group included patients with IVIG reactions that were not haemolytic, and registry patients with no-reaction were the 'no-reaction controls'. Descriptive analysis and two logistic regression models for the different control groups were performed. RESULTS: One thousand one hundred and seventy reactions were included. Most common were febrile non haemolytic (26.1%), minor allergic (24.5%) and IVIG headache (15.3%) followed by haemolytic 10.9% (128/1170). Haemolytic reaction rates decreased over time: rates since 2020 estimated between 1.5 and 2.9/1000 kg IVIG used. The regression model for other-reaction controls identified two risk factors for haemolysis: non-O blood group recipients compared with group O recipients (p value = 0.0106) and IVIG dose per 10 g increase (OR 1.359; 95% CI 1.225-1.506). The model using no-reaction controls gave similar results and also showed no pre-medication was associated with a higher risk of haemolysis (OR 29.084; 95% CI 1.989-425.312). CONCLUSION: The frequency of haemolytic reactions has decreased over time. We confirmed non-O blood group recipients and IVIG dose as risk factors for haemolysis and raise the hypothesis that no pre-medication may increase the risk of haemolysis.

An evaluation of the clinical impacts of 7-day platelets.

BACKGROUND: In August 2017, Canadian Blood Services extended the shelf-life of platelet concentrates from 5 to 7 days. The clinical impacts of this policy change remain unclear. STUDY DESIGN AND METHODS: We used a before-after retrospective design of platelet-transfused adult inpatients in Hamilton, ON, Canada. Data were captured for 18 months before (Period 1: February 2016-July 2017) and 18 months after (Period 2: September 2017-February 2019) 7-day platelet implementation. Primary outcome was absolute platelet count increment (ACI) in univariate and multivariate analyses adjusted for confounders. Data were obtained from our institution's transfusion database, Ontario's Transfusion Transmitted Injuries Surveillance System, and the blood supplier. RESULTS: Overall, 1360 patients with single dose platelet transfusions were included in Period 1 and 1211 patients in Period 2. Median age at admission was 66 years, and approximately 40% of patients underwent cardiac surgery. Using a non-inferiority margin of -10 × 109 /L, platelets transfused during the 7-day storage period were non-inferior to those transfused in the 5-day storage period [mean count difference - 4.63 × 109 /L (95% CI -7.40 to -1.87, p = 0.0001)]. However, platelet ACIs following transfusion consistently trended lower in the 7-day group for all patients and subgroups. No differences in secondary clinical outcomes were observed. Platelet expiry reduced from 8.1 to 6.3% (p < 0.0001). CONCLUSION: Platelet transfusions following 7-day storage policy were non-inferior to transfusions in the 5-day policy period, although reduced ACIs were observed. There were no increases in adverse clinical outcomes.

Definition of a critical bleed in patients with immune thrombocytopenia: Communication from the ISTH SSC Subcommittee on Platelet Immunology.

BACKGROUND: Immune thrombocytopenia (ITP) is an autoimmune disease characterized by low platelet counts and increased risk of bleeding. In preparation for an upcoming guideline, the ITP Emergency Management Guideline Panel, including clinical experts in hematology, emergency medicine, research methodology, and patient representatives, identified the need for a standardized definition of a critical ITP bleed. The goal of the definition was to distinguish critical bleeds from bleeds that may not require urgent treatment, typically in the context of severe thrombocytopenia. METHODS: The panel met in person and virtually to achieve consensus on the criteria for critical bleeding events among patients with ITP. Existing ITP bleeding scores and published definitions of major bleeds in patients receiving anticoagulation informed the definition of a critical ITP bleed. The Platelet Immunology Scientific Standardization Committee (SSC) of the International Society on Thrombosis and Haemostasis endorsed the definition. RESULTS: A critical ITP bleed was defined as: (a) a bleed in a critical anatomical site including intracranial, intraspinal, intraocular, retroperitoneal, pericardial, or intramuscular with compartment syndrome; or (2) an ongoing bleed that results in hemodynamic instability or respiratory compromise. CONCLUSION: The definition of a critical ITP bleed was developed by the ITP Emergency Management Guideline Panel and endorsed by the Platelet Immunology SSC. It incorporates both anatomic and physiologic risk and pertains to patients with confirmed or suspected ITP who typically have severe thrombocytopenia (platelet count below 20 × 109 /L).

A prospective multi-faceted interventional study of blood bank technologist screening of red blood cell transfusion orders: The START study.

BACKGROUND: Transfusion of red blood cells (RBC) is a common procedure, which when prescribed inappropriately can result in adverse patient outcomes. This study sought to determine the impact of a multi-faceted intervention on unnecessary RBC transfusions at hospitals with a baseline appropriateness below 90%. STUDY DESIGN AND METHODS: A prospective medical chart audit of RBC transfusions was conducted across 15 hospitals. For each site, 10 RBCs per month transfused to inpatients were audited for a 5-month pre- and 10-month post-intervention period, with each transfusion adjudicated for appropriateness based on pre-set criteria. Hospitals with appropriateness rates below 90% underwent a 3-month intervention which included: adoption of standardized RBC guidelines, staff education, and prospective transfusion order screening by blood bank technologists. Proportions of RBC transfusions adjudicated as appropriate and the total number of RBC units transfused per month in the pre- and post-intervention period were examined. RESULTS: Over the 15-month audit period, at the 13 hospital sites with a baseline appropriateness below 90%, 1950 patients were audited of which 81.2% were adjudicated as appropriate. Proportions of appropriateness and single-unit orders increased from 73.5% to 85% and 46.2% to 68.2%, respectively from pre- to post-intervention (P < .0001). Pre- and post-transfusion hemoglobin levels and the total number of RBCs transfused decreased from baseline (P < .05). The median pre-transfusion hemoglobin decreased from a baseline of 72.0 g/L to 69.0 g/L in the post-intervention period (P < .0001). RBC transfusions per acute inpatient days decreased significantly in intervention hospitals, but not in control hospitals (P < .001). The intervention had no impact on patient length of stay, need for intensive care support, or in-hospital mortality. CONCLUSION: This multifaceted intervention demonstrated a marked improvement in RBC transfusion appropriateness and reduced overall RBC utilization without impacts on patient safety.

Systematic review of rituximab for autoimmune diseases: a potential alternative to intravenous immune globulin.

BACKGROUND: The anti-CD20 monoclonal antibody rituximab has immune-modulatory effects similar to intravenous immunoglobulin (IVIG). We performed a systematic review and meta-analysis to determine the efficacy and safety of rituximab in autoimmune diseases that are also treated with IVIG. STUDY DESIGN AND METHODS: The most common indications for immune modulation with IVIG, as identified from a 2012 regional audit in Canada, were chronic inflammatory demyelinating polyneuropathy (CIDP), immune thrombocytopenia (ITP), myasthenia gravis, multifocal motor neuropathy, Guillain-Barré syndrome, systemic lupus erythematosus (SLE), Sjogren's syndrome, and pemphigus vulgaris. We searched MEDLINE, EMBASE, and the Cochrane Library until July 2016 for studies evaluating rituximab in each of these conditions. The primary outcome in our meta-analysis was clinical response at 6 months as defined by disease-specific criteria in randomized trials. We also calculated pooled proportions of responders within disease types from observational studies. RESULTS: Ninety-five rituximab studies were identified: 86 were observational studies in patients with ITP (n = 1746), SLE (n = 1047), pemphigus vulgaris (n = 564), Sjogren's syndrome (n = 138), myasthenia gravis (n = 66), and CIDP (n = 31) and nine were randomized controlled trials (n = 992) in patients with ITP, SLE, and Sjogren's syndrome that compared rituximab with placebo plus standard of care. Among randomized trials, response rates were higher with rituximab (relative risk, 1.38; 95% confidence interval [CI], 1.05-1.83). The pooled proportion of rituximab responses ranged from 94% (95% CI, 88%-98%) for pemphigus vulgaris to 48% (95% CI, 30%-66%) for CIDP. Rituximab was generally well tolerated in observational studies although in the randomized trials, adverse events were more common in the rituximab group. CONCLUSION: Rituximab is an immune-modulating agent with biologic activity across many autoimmune conditions. Our data support the use of comparative trials with broad eligibility criteria to evaluate rituximab as an alternative to IVIG in autoimmune diseases.

Quality of Evidence-Based Guidelines for Transfusion of Red Blood Cells and Plasma: A Systematic Review.

Many transfusion guidelines are available, but little appraisal of their quality has been undertaken. The quality of guidelines may potentially influence adoption. Our aim was to determine the quality of evidence-based transfusion guidelines (EBG) for red cells and plasma, using the Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument, and assess duplication and consistency of recommendations. MEDLINE and EMBASE were systematically searched for EBG from 2005 to June 3, 2016. Citations were reviewed for inclusion in duplicate. A guideline was included if it had a specified clinical question, described a systematic search strategy, included critical appraisal of the literature and a description of how recommendations were developed. Four to six physicians used AGREE II to appraise each guideline. Median and scaled scores were calculated, with each item scored on a scale of one to seven, seven representing the highest score. Of 6174 citations, 30 guidelines met inclusion criteria. Twenty six guidelines had recommendations for red cells and 18 included recommendations for plasma use. The median score, the scaled score and the interquartile range of the scaled score were: scope and purpose: median score 5, scaled score 60%, IQR (49-74%); stakeholder involvement 4, 43%, (33-49%); rigor of development 4, 41%, (19-59%); clarity of presentation 5, 69%, (52-81%); applicability 1, 16%, (9-23%); editorial independence 3, 43%, (20-58%). Sixteen guidelines were evaluated to have a scaled domain score of 50% or less. Variations in recommendations were found for the use of hemoglobin triggers for red cell transfusion in patients with acute coronary syndromes and for plasma use for patients with bleeding. Our findings document, limited rigor in guideline development and duplication and inconsistencies in recommendations for the same topic. The process of developing guidelines for red cells and plasma transfusion can be enhanced to improve implementation.

Red blood cell storage and in-hospital mortality: a secondary analysis of the INFORM randomised controlled trial.

BACKGROUND: No randomised trials have addressed whether exposure to red blood cells (RBCs) stored longer than 35 days is associated with harm in patients. We aimed to assess the risk of in-hospital mortality associated with transfusing blood stored longer than 35 days. METHODS: We did a secondary analysis of the INforming Fresh versus Old Red cell Management (INFORM) trial, a pragmatic, multicentre, randomised controlled trial of patients (≥18 years) admitted to one of six hospitals in Australia, Canada, Israel, and the USA and expected to need RBC transfusions. Patients were randomly assigned (2:1) to receive blood in inventory stored for the longest time (standard care) or the shortest time, using a random allocation schedule and stratified by centre and patient ABO blood group. The primary objective of the INFORM trial was to assess all-cause in-hospital mortality in patients with blood group A and O who were transfused. For our exploratory secondary analysis, we classified individuals into one of three mutually exclusive exposure categories on the basis of the maximum storage duration of any blood unit patients had received on each day in hospital: exclusively exposed to RBCs stored no longer than 7 days, exposed to at least one unit of RBCs stored 8-35 days, and exposed to least one unit of RBCs stored longer than 35 days. Our primary objective was to determine the effect on risk of in-hospital death of time-dependent exposure to RBCs stored longer than 35 days compared with exclusive exposure to RBCs stored no longer than 7 days, both in patients of blood groups A and O and all patients. The INFORM trial is registered as an International Standard Randomised Controlled Trial, number ISRCTN08118744. FINDINGS: Between April 2, 2012, and Oct 21, 2015, 31 497 patients were recruited, and 24 736 patients were eligible for inclusion in this analysis. We excluded nine patients for whom information about the storage duration of transfused blood was missing and one patient whose sex was unknown. 4480 (18%) patients were exposed to RBCs with longest storage, 1392 (6%) patients were exposed exclusively to RBCs with shortest storage, and 18 854 (76%) patients were exposed to RBCs stored 8-35 days. Median follow-up was 11 days (IQR 6-20). Exposure to RBCs stored longer than 35 days was not associated with increased risk of in-hospital death compared with exclusive exposure to the freshest RBC units after adjusting for demographic variables, diagnosis category, and blood product use history (in patients with blood group A or O: hazard ratio 0·94, 95% CI 0·73-1·20, p=0·60; in all patients: 0·91, 0·72-1·14, p=0·40). The risk of in-hospital death also did not differ between patients exposed to blood stored 8-35 days and patients exposed to blood stored 7 days or less (in patients with blood group A or O: 0·92, 0·74-1·15, p=0·48; in all patients: 0·90, 0·73-1·10, p=0·29). INTERPRETATION: These data provide evidence that transfusion of blood stored for longer than 35 days has no effect on in-hospital mortality, which suggests that current approaches to blood storage and inventory management are reasonable. FUNDING: Canadian Institutes for Health Research, Canadian Blood Services, and Health Canada.

The association between platelet transfusions and bleeding in critically ill patients with thrombocytopenia.

BACKGROUND: Platelet transfusions are commonly used to treat critically ill patients with thrombocytopenia. Whether platelet transfusions are associated with a reduction in the risk of major bleeding is unknown. PATIENTS/METHODS: Observational cohort study nested in a previous multicenter, randomized thromboprophylaxis trial in the intensive care unit (ICU). The objective was to evaluate the association between platelet transfusions and adjudicated major bleeding events. Platelet transfusion episodes were reviewed for timing of administration, product type, and dose. Major bleeding with and without platelet transfusions was adjusted for severity of thrombocytopenia, use of anti-platelet agents, surgery and other covariates. Secondary outcomes were thrombosis, death in ICU and platelet count increment. RESULTS: Among 2,256 patients, 71 (3.1%) received 190 platelet transfusions. Of those, 121 (63.7%) were administered to 54 non-bleeding, thrombocytopenic patients. Adjusted rates of major bleeding were not statistically different with or without the administration of platelet transfusions (hazard ratio for transfused patients 0.85; 95% confidence interval, 0.42-1.72). We did not find a significant association between platelet transfusion use and thrombosis or death in ICU in adjusted analyses. Thrombocytopenia, anemia, major or minor bleeding and use of anticoagulants were associated with platelet transfusion administration. The median post-transfusion platelet count increment was 20×109/L at 3.5 hours post-transfusion. CONCLUSIONS: Rates of major bleeding were not different for patients who did and did not receive platelet transfusions. Inferences were limited by the small number of transfused patients. Clinical trials are needed to better investigate the potential hemostatic benefit and potential harms of platelet transfusions for this high-risk population.

Effect of Short-Term vs. Long-Term Blood Storage on Mortality after Transfusion.

BACKGROUND: Randomized, controlled trials have suggested that the transfusion of blood after prolonged storage does not increase the risk of adverse outcomes among patients, although most of these trials were restricted to high-risk populations and were not powered to detect small but clinically important differences in mortality. We sought to find out whether the duration of blood storage would have an effect on mortality after transfusion in a general population of hospitalized patients. METHODS: In this pragmatic, randomized, controlled trial conducted at six hospitals in four countries, we randomly assigned patients who required a red-cell transfusion to receive blood that had been stored for the shortest duration (short-term storage group) or the longest duration (long-term storage group) in a 1:2 ratio. Only patients with type A or O blood were included in the primary analysis, since pilot data suggested that our goal of achieving a difference in the mean duration of blood storage of at least 10 days would not be possible with other blood types. Written informed consent was waived because all the patients received treatment consistent with the current standard of care. The primary outcome was in-hospital mortality, which was estimated by means of a logistic-regression model after adjustment for study center and patient blood type. RESULTS: From April 2012 through October 2015, a total of 31,497 patients underwent randomization. Of these patients, 6761 who did not meet all the enrollment criteria were excluded after randomization. The primary analysis included 20,858 patients with type A or O blood. Of these patients, 6936 were assigned to the short-term storage group and 13,922 to the long-term storage group. The mean storage duration was 13.0 days in the short-term storage group and 23.6 days in the long-term storage group. There were 634 deaths (9.1%) in the short-term storage group and 1213 (8.7%) in the long-term storage group (odds ratio, 1.05; 95% confidence interval [CI], 0.95 to 1.16; P=0.34). When the analysis was expanded to include the 24,736 patients with any blood type, the results were similar, with rates of death of 9.1% and 8.8%, respectively (odds ratio, 1.04; 95% CI, 0.95 to 1.14; P=0.38). Additional results were consistent in three prespecified high-risk subgroups (patients undergoing cardiovascular surgery, those admitted to intensive care, and those with cancer). CONCLUSIONS: Among patients in a general hospital population, there was no significant difference in the rate of death among those who underwent transfusion with the freshest available blood and those who underwent transfusion according to the standard practice of transfusing the oldest available blood. (Funded by the Canadian Institutes of Health Research and others; INFORM Current Controlled Trials number, ISRCTN08118744 .).

Evaluating appropriate red blood cell transfusions: a quality audit at 10 Ontario hospitals to determine the optimal measure for assessing appropriateness.

BACKGROUND: Evaluating the appropriateness of red blood cell (RBC) transfusion requires labor-intensive medical chart audits and expert adjudication. We sought to determine the appropriateness of RBC transfusions at 10 hospitals using retrospective chart review and to determine whether simple metrics (proportion of single-unit transfusions, RBCs/100 acute inpatient days, proportion of transfusions with pretransfusion hemoglobin <80 g/L or posttransfusion hemoglobin <90 g/L) could be used as surrogate markers of appropriateness by comparing their values with the results from the audit. STUDY DESIGN AND METHODS: An initial block of 30 RBC units was dually adjudicated for appropriateness followed by additional blocks of 10 units until the difference between the cumulative percentage of appropriate RBC units in the preceding block and final block was <3%. Pearson correlation tests were used to evaluate associations between the metrics and percentages of appropriate transfusions per hospital. Two-by-two tables were used to assess the utility of the metrics to classify transfusions for appropriateness. RESULTS: Of the 498 units audited, 78% were adjudicated as appropriate (κ = 0.9603), with significant variability between institutions (p < 0.0001). Fifty audits or less were required at nine of the institutions. The values of the metrics were not found to have significant correlations with appropriateness, and the metric that misclassified the smallest proportion of transfusions for appropriateness was pretransfusion hemoglobin <80 g/L, at 24%. CONCLUSIONS: Our findings suggest that a chart audit of 50 RBC transfusions with adjudication using robust criteria is the optimal means of evaluating RBC transfusion appropriateness at an institution for benchmarking and quality-improvement initiatives.

Red blood cell processing methods and in-hospital mortality: a transfusion registry cohort study.

BACKGROUND: Quality of red blood cells (RBCs) varies depending on the method of processing the whole blood donation, and the method of processing might affect outcomes in patients transfused RBCs. We aimed to establish whether an association exists between in-hospital mortality and RBC processing method and duration of storage. METHODS: We did a retrospective registry cohort study using data from three acute care hospitals in Hamilton, ON, Canada, and Canadian Blood Services over a 6-year period (2008-14). Adult patients (≥18 years) who were admitted to hospital and who received RBC transfusions were included in the study. All transfused RBCs were characterised by the method of processing (red cell filtered or whole blood filtered) and storage age (fresh 1-7 days, mid 8-35 days, and old 36-42 days). The primary outcome was in-hospital mortality. We used Cox proportional hazards regression with time-dependent stratification variables and fixed stratification variables, and controlled for patient covariates. FINDINGS: Between April 1, 2008, and March 31, 2014, 91 065 RBC transfusions were given to 23 634 adults who were included in the analyses. When storage duration was included in the model, in-hospital mortality was significantly increased with fresh whole blood filtered units compared with the reference group of mid-age red cell filtered units (hazard ratio 2·19, 95% CI 1·09-4·42; p=0·033). Differences between other age and processing categories were not significant. INTERPRETATION: The potential effect of whole blood processing methods on patient outcomes is worthy of further investigation, since adverse outcomes could be reduced by minor changes to blood processing methods and inventory management policies. FUNDING: Canadian Blood Services, Health Canada, and the Canadian Institutes of Health Research.

AABB Committee Report: reducing transfusion-transmitted cytomegalovirus infections.

Transfusion-transmitted cytomegalovirus (TT-CMV) is often asymptomatic, but certain patient populations, such as very low birth weight neonates, fetuses requiring intrauterine transfusion, pregnant women, patients with primary immunodeficiencies, transplant recipients, and patients receiving chemotherapy or transplantation for malignant disease, may be at risk of life-threatening CMV infection. It is unclear whether leukoreduction of cellular blood components is sufficient to reduce TT-CMV or whether CMV serological testing adds additional benefit to leukoreduction. The AABB CMV Prevention Work Group commissioned a systematic review to address these issues and subsequently develop clinical practice guidelines. However, the data were of poor quality, and no studies of significant size have been performed for over a decade. Rather than creating guidelines of questionable utility, the Work Group (with approval of the AABB Board of Directors) voted to prepare this Committee Report. There is wide variation in practices of using leukoreduced components alone or combining CMV-serology and leukoreduction to prevent TT-CMV for at-risk patients. Other approaches may also be feasible to prevent TT-CMV, including plasma nucleic acid testing, pathogen inactivation, and patient blood management programs to reduce the frequency of inappropriate transfusions. It is unlikely that future large-scale clinical trials will be performed to determine whether leukoreduction, CMV-serology, or a combination of both is superior. Consequently, alternative strategies including pragmatic randomized controlled trials, registries, and collaborations for electronic data merging, nontraditional approaches to inform evidence, or development of a systematic approach to inform expert opinion may help to address the issue of CMV-safe blood components.

Rationale and Design of the Informing Fresh versus Old Red Cell Management (INFORM) Trial: An International Pragmatic Randomized Trial.

Although red blood cell transfusion is a potentially lifesaving intervention in severely anemic and acutely bleeding patients, some observational studies have suggested that prolonged red cell storage before transfusion is associated with harm. INFORM is a large, pragmatic, randomized controlled trial comparing the effect of the shorter storage with longer storage red blood cell transfusions on inhospital mortality in hospitalized patients who require a blood transfusion. The trial is being conducted in centers in Australia, Canada, Israel, and the United States and is expected to enroll 31497 patients. If the results of INFORM indicate that shorter storage red blood cell transfusion is associated with superior outcomes compared with standard issue red blood cell transfusion, consideration may be given to shortening blood storage times. If, in contrast, the INFORM trial provides no evidence of harm from longer storage red blood cells, clinicians and patients may be reassured that current blood inventory management strategies are appropriate.

The prevalence of anti-K in Canadian prenatal patients.

BACKGROUND: Anti-KEL1(K) is a major cause of hemolytic disease of the fetus and newborn. We utilized data from prenatal testing of patients in Western Canada to determine the frequency of anti-K. In Manitoba, we evaluated the frequency of transfusion as the likely cause for alloimmunization. We reviewed international practices to prevent alloimmunization. STUDY DESIGN AND METHODS: Prenatal patients undergo antibody screening using an automated testing platform and uniform testing algorithm. Data on the frequency of antibodies, transfusion history, and donor K typing were extracted from the relevant databases at Canadian Blood Services. National standards were reviewed with the help of local experts. RESULTS: Anti-K was found in 397 of 390,193 patients from 2011 to 2013 (1.02 per 1000) and was the second most frequent antibody after anti-E. In Manitoba, 26 of 75 (35%) anti-K patients had received transfusions in the province since 2001; 14 of the 26 (54%) had received at least one K+ RBC unit and three had received all K- units, while in nine, donor K typing was incomplete. Only eight of the 26 had previous pregnancies, three with K+ partners. International practice varies; however, prophylactic use of matched or K- units is standard in many European countries. CONCLUSIONS: Anti-K was found in 0.1% of prenatal patients. Although our data on the history of transfusion are incomplete, they demonstrate that transfusion with a K+ unit is a major cause of alloimmunization. Given advances in phenotyping and genotyping technologies, prophylactic matching should be considered in Canada.

Platelet transfusion: a clinical practice guideline from the AABB.

BACKGROUND: The AABB (formerly, the American Association of Blood Banks) developed this guideline on appropriate use of platelet transfusion in adult patients. METHODS: These guidelines are based on a systematic review of randomized, clinical trials and observational studies (1900 to September 2014) that reported clinical outcomes on patients receiving prophylactic or therapeutic platelet transfusions. An expert panel reviewed the data and developed recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework. RECOMMENDATION 1: The AABB recommends that platelets should be transfused prophylactically to reduce the risk for spontaneous bleeding in hospitalized adult patients with therapy-induced hypoproliferative thrombocytopenia. The AABB recommends transfusing hospitalized adult patients with a platelet count of 10 × 109 cells/L or less to reduce the risk for spontaneous bleeding. The AABB recommends transfusing up to a single apheresis unit or equivalent. Greater doses are not more effective, and lower doses equal to one half of a standard apheresis unit are equally effective. (Grade: strong recommendation; moderate-quality evidence). RECOMMENDATION 2: The AABB suggests prophylactic platelet transfusion for patients having elective central venous catheter placement with a platelet count less than 20 × 109 cells/L. (Grade: weak recommendation; low-quality evidence). RECOMMENDATION 3: The AABB suggests prophylactic platelet transfusion for patients having elective diagnostic lumbar puncture with a platelet count less than 50 × 109 cells/L. (Grade: weak recommendation; very-low-quality evidence). RECOMMENDATION 4: The AABB suggests prophylactic platelet transfusion for patients having major elective nonneuraxial surgery with a platelet count less than 50 × 109 cells/L. (Grade: weak recommendation; very-low-quality evidence). RECOMMENDATION 5: The AABB recommends against routine prophylactic platelet transfusion for patients who are nonthrombocytopenic and have cardiac surgery with cardiopulmonary bypass. The AABB suggests platelet transfusion for patients having bypass who exhibit perioperative bleeding with thrombocytopenia and/or evidence of platelet dysfunction. (Grade: weak recommendation; very-low-quality evidence). RECOMMENDATION 6: The AABB cannot recommend for or against platelet transfusion for patients receiving antiplatelet therapy who have intracranial hemorrhage (traumatic or spontaneous). (Grade: uncertain recommendation; very-low-quality evidence).

Platelet utilization: a Canadian Blood Services research and development symposium.

Considerable progress has been made in recent years in understanding platelet biology and in strengthening the clinical evidence base around platelet transfusion thresholds and appropriate platelet dosing. Platelet alloimmunization rates have also declined. Nevertheless, controversies and uncertainties remain that are relevant to how these products can best be used for the benefit of platelet transfusion recipients. Platelets are unique among the blood products directly derived from whole blood or apheresis donations in requiring storage, with shaking, at ambient temperature. Storage is accordingly constrained between the need to limit the growth of any microbes in the product and the need to minimize losses in platelet function associated with storage. Proteomic and genomic approaches are being applied to the platelet storage lesion. Platelet inventory management is made challenging by these constraints. Although bacterial screening has enhanced the safety of platelet transfusions, pathogen reduction technology may offer further benefits. Continuing clinical investigations are warranted to understand the value of transfusing platelets prophylactically or only in response to bleeding in different patient groups and how best to manage the most grievously injured trauma patients. Patients refractory to platelet transfusions also require expert clinical management. The engineering of platelet substitute products is an active area of research, but considerable hurdles remain before any clinical uses may be contemplated. Roles for platelets in biological areas distinct from hemostasis are also emerging. Platelet utilization is variably affected by all of the above factors, by demographic changes, by new medications, and by new patient care approaches.

Acquired hemophilia A.

Acquired hemophilia A is a rare, autoimmune disorder that is caused by autoantibodies that act as inhibitors to factor VIII. It is characterized by severe, unexpected bleeding that may be life-threatening. The incidence of acquired hemophilia A is ~ 0.2 to 1.48 cases per 1 million individuals per year. Acquired hemophilia A has been associated with several clinical conditions including pregnancy, autoimmune or collagen vascular disorders, malignancies, drugs, respiratory disorders, and infections. However, in ~ 50% of cases, no disease association is determined. Acquired hemophilia A should be suspected when a patient with no previous personal or family history of bleeding, presents with bleeding and an unexplained prolonged activated partial thromboplastin time (APTT) and other common causes of a prolonged APTT are ruled out. The treatment of acquired hemophilia A has two main goals: (1) to treat and/or prevent bleeding complications and (2) to eradicate the inhibitor. The recommended agents to be used for the treatment or prevention of bleeding in patients with acquired hemophilia A are the bypassing agents. Patients should be treated initially with corticosteroids, either alone or in combination with cyclophosphamide, to eradicate the inhibitor.