COVID-19 convalescent plasma.

As the coronavirus disease (COVID-19) pandemic led to a global health crisis, there were limited treatment options and no prophylactic therapies for those exposed to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Convalescent plasma is quick to implement, potentially provides benefits, and has a good safety profile. The therapeutic potential of COVID-19 convalescent plasma (CCP) is likely mediated by antibodies through direct viral neutralization and Fc-dependent functions such as a phagocytosis, complement activation, and antibody-dependent cellular cytotoxicity. In the United States, CCP became one of the most common treatments with more than a half million units transfused despite limited efficacy data. More than a dozen randomized trials now demonstrate that CCP does not provide benefit for those hospitalized with moderate to severe disease. However, similar to other passive antibody therapies, CCP is beneficial for early disease when provided to elderly outpatients within 72 hours after symptom onset. Only high-titer CCP should be transfused. CCP should also be considered for immunosuppressed patients with COVID-19. CCP collected in proximity, by time and location, to the patient may be more beneficial because of SARS-CoV-2 variants. Additional randomized trial data are still accruing and should be incorporated with other trial data to optimize CCP indications.

How do transfusion services manage patients taking therapies such as anti-CD38 and anti-CD47 known to interfere with red blood cell compatibility testing?

BACKGROUND: Drugs such as daratumumab (Darzalex, anti-CD38) and Hu5F9-G4 (magrolimab, anti-CD47) may interfere with red blood cell compatibility testing as CD38 and CD47 are expressed on red blood cells. STUDY DESIGN AND METHODS: A survey of AABB member transfusion services was undertaken to understand their experiences of managing patients taking therapeutic monoclonal antibodies that are known to interfere with blood grouping and compatibility testing. RESULTS: The survey was distributed to the contact person at US-based AABB member transfusion services. The response rate was 27%. 172 of 240 (72%) indicated they had difficulties in performing compatibility testing in patients taking daratumumab and 66 of 91 (73%) reported difficulties in performing compatibility testing in patients taking magrolimab. Actions taken to provide compatible blood for these patients included referral of all samples to a reference center, blood group pheno/genotyping the patient in advance of starting the drug, treating reagent cells with 0.2 M dithiothreitol and using K-negative red cell units for patients taking daratumumab, and Gamma-clone (Immucor) anti-IgG for indirect antiglobulin testing for patients taking magrolimab. Lack of communication from clinical services about drug treatment was identified as a concern. CONCLUSION: The results of the survey demonstrate that transfusion services are having challenges with the transfusion management of patients taking therapeutic monoclonal antibodies, and further education is needed.

Current advances in 2022: A critical review of selected topics by the Association for the Advancement of Blood and Biotherapies (AABB) Clinical Transfusion Medicine Committee.

BACKGROUND: The Association for the Advancement of Blood and Biotherapies Clinical Transfusion Medicine Committee (CTMC) composes a summary of new and important advances in transfusion medicine (TM) on an annual basis. Since 2018, this has been assembled into a manuscript and published in Transfusion. STUDY DESIGN AND METHODS: CTMC members selected original manuscripts relevant to TM that were published electronically and/or in print during calendar year 2022. Papers were selected based on perceived importance and/or originality. References for selected papers were made available to CTMC members to provide feedback. Members were also encouraged to identify papers that may have been omitted initially. They then worked in groups of two to three to write a summary for each new publication within their broader topic. Each topic summary was then reviewed and edited by two separate committee members. The final manuscript was assembled by the first and senior authors. While this review is extensive, it is not a systematic review and some publications considered important by readers may have been excluded. RESULTS: For calendar year 2022, summaries of key publications were assembled for the following broader topics within TM: blood component therapy; infectious diseases, blood donor testing, and collections; patient blood management; immunohematology and genomics; hemostasis; hemoglobinopathies; apheresis and cell therapy; pediatrics; and health care disparities, diversity, equity, and inclusion. DISCUSSION: This Committee Report reviews and summarizes important publications and advances in TM published during calendar year 2022, and maybe a useful educational tool.

Clinical Practice Guidelines From the Association for the Advancement of Blood and Biotherapies (AABB): COVID-19 Convalescent Plasma.

DESCRIPTION: Coronavirus disease 2019 convalescent plasma (CCP) has emerged as a potential treatment of COVID-19. However, meta-analysis data and recommendations are limited. The Association for the Advancement of Blood and Biotherapies (AABB) developed clinical practice guidelines for the appropriate use of CCP. METHODS: These guidelines are based on 2 living systematic reviews of randomized controlled trials (RCTs) evaluating CCP from 1 January 2019 to 26 January 2022. There were 33 RCTs assessing 21 916 participants. The results were summarized using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) method. An expert panel reviewed the data using the GRADE framework to formulate recommendations. RECOMMENDATION 1 (OUTPATIENT): The AABB suggests CCP transfusion in addition to the usual standard of care for outpatients with COVID-19 who are at high risk for disease progression (weak recommendation, moderate-certainty evidence). RECOMMENDATION 2 (INPATIENT): The AABB recommends against CCP transfusion for unselected hospitalized persons with moderate or severe disease (strong recommendation, high-certainty evidence). This recommendation does not apply to immunosuppressed patients or those who lack antibodies against SARS-CoV-2. RECOMMENDATION 3 (INPATIENT): The AABB suggests CCP transfusion in addition to the usual standard of care for hospitalized patients with COVID-19 who do not have SARS-CoV-2 antibodies detected at admission (weak recommendation, low-certainty evidence). RECOMMENDATION 4 (INPATIENT): The AABB suggests CCP transfusion in addition to the usual standard of care for hospitalized patients with COVID-19 and preexisting immunosuppression (weak recommendation, low-certainty evidence). RECOMMENDATION 5 (PROPHYLAXIS): The AABB suggests against prophylactic CCP transfusion for uninfected persons with close contact exposure to a person with COVID-19 (weak recommendation, low-certainty evidence). GOOD CLINICAL PRACTICE STATEMENT: CCP is most effective when transfused with high neutralizing titers to infected patients early after symptom onset.

Red Blood Cell Transfusion: 2023 AABB International Guidelines.

Importance: Red blood cell transfusion is a common medical intervention with benefits and harms. Objective: To provide recommendations for use of red blood cell transfusion in adults and children. Evidence Review: Standards for trustworthy guidelines were followed, including using Grading of Recommendations Assessment, Development and Evaluation methods, managing conflicts of interest, and making values and preferences explicit. Evidence from systematic reviews of randomized controlled trials was reviewed. Findings: For adults, 45 randomized controlled trials with 20 599 participants compared restrictive hemoglobin-based transfusion thresholds, typically 7 to 8 g/dL, with liberal transfusion thresholds of 9 to 10 g/dL. For pediatric patients, 7 randomized controlled trials with 2730 participants compared a variety of restrictive and liberal transfusion thresholds. For most patient populations, results provided moderate quality evidence that restrictive transfusion thresholds did not adversely affect patient-important outcomes. Recommendation 1: for hospitalized adult patients who are hemodynamically stable, the international panel recommends a restrictive transfusion strategy considering transfusion when the hemoglobin concentration is less than 7 g/dL (strong recommendation, moderate certainty evidence). In accordance with the restrictive strategy threshold used in most trials, clinicians may choose a threshold of 7.5 g/dL for patients undergoing cardiac surgery and 8 g/dL for those undergoing orthopedic surgery or those with preexisting cardiovascular disease. Recommendation 2: for hospitalized adult patients with hematologic and oncologic disorders, the panel suggests a restrictive transfusion strategy considering transfusion when the hemoglobin concentration is less than 7 g/dL (conditional recommendations, low certainty evidence). Recommendation 3: for critically ill children and those at risk of critical illness who are hemodynamically stable and without a hemoglobinopathy, cyanotic cardiac condition, or severe hypoxemia, the international panel recommends a restrictive transfusion strategy considering transfusion when the hemoglobin concentration is less than 7 g/dL (strong recommendation, moderate certainty evidence). Recommendation 4: for hemodynamically stable children with congenital heart disease, the international panel suggests a transfusion threshold that is based on the cardiac abnormality and stage of surgical repair: 7 g/dL (biventricular repair), 9 g/dL (single-ventricle palliation), or 7 to 9 g/dL (uncorrected congenital heart disease) (conditional recommendation, low certainty evidence). Conclusions and Relevance: It is good practice to consider overall clinical context and alternative therapies to transfusion when making transfusion decisions about an individual patient.

Safety and tolerability of solvent/detergent-treated plasma for pediatric patients requiring therapeutic plasma exchange: An open-label, multicenter, postmarketing study.

BACKGROUND: This study investigated the real-world safety and tolerability of solvent/detergent-treated (S/D) plasma for pediatric patients requiring therapeutic plasma exchange (TPE). STUDY DESIGN AND METHODS: LAS-213 was a multicenter, open-label, interventional, phase 4 study. Patients (≥2 to ≤20 years) receiving TPE therapy were eligible. A total plasma volume of 40-60 ml/kg was recommended, with an infusion rate not exceeding 0.020-0.025 citrate/kg body weight/min (<1 ml/kg body weight/min). The primary endpoint was assessment of safety, monitoring the following: serious adverse events (SAEs), adverse drug reactions (ADRs), thrombotic events (TEs), thromboembolic events (TEEs), and specific laboratory tests. RESULTS: In total, 41 children (2 to <12 years [n = 15]; 12 to <17 years [n = 13]; ≥17 years [n = 13]) underwent 102 TPEs with a total of 135,137 ml of S/D plasma exchanged. Each patient group received between 1 and 6 TPEs (mean: 2.5 TPEs). Actual dose administered per TPE was 4-72 ml/kg (mean: 28.6 ml/kg), with a mean total volume of 1324.9 ml (range: 113-4000 ml). Overall safety was excellent for 96/102 (94.0%) TPEs. Six TPEs had a "moderate" safety profile for four patients experiencing eight ADRs. Of these, seven were mild in intensity and one (pyrexia) was moderate, all resolving by study end. Mild citrate toxicity (n = 2) was the most common ADR. One SAE was reported but was unrelated to the study drug. No TEs, TEEs, or changes in laboratory safety parameters were reported. CONCLUSION: S/D plasma was well tolerated and demonstrated favorable safety, supporting the use of S/D plasma for TPE in pediatrics.

Vitamin K antagonist reversal strategies: Systematic review and network meta-analysis from the AABB.

BACKGROUND: Anticoagulation requires urgent reversal in cases of life-threatening bleeding or invasive procedures. STUDY DESIGN AND METHODS: Network meta-analysis for comparing the safety and efficacy of warfarin reversal strategies including plasma and prothrombin complex concentrates (PCCs). RESULTS: Seven studies including 594 subjects using reversal agents plasma, 3-factor-PCC (Uman Complex and Konyne), and 4-factor-PCC (Beriplex/KCentra, Octaplex, and Cofact) met inclusion criteria. Compared with plasma, patients receiving Cofact probably have a higher rate of international normalized ratio (INR) correction (risk difference [RD] 499 more per 1000 patients, 95% confidence interval [CI], 176-761, low certainty[LC]); higher reversal of bleeding (323 more per 1000 patients, 11-344 more, LC); and fewer transfusion requirements (0.96 fewer units, 1.65-0.27 fewer, LC). Patients receiving Beriplex/KCentra probably have a higher rate of INR correction (476 more per 1000 patients, 332-609 more, LC); higher reversal of bleeding (127 more per 1000 patients, 43 fewer to 236 more); and similar transfusion requirements (0.01 fewer units, 0.31 fewer to 0.28 more, high/moderate certainty). Patients receiving Octaplex probably have a higher rate of INR correction (RD 579 more per 1000 patients, 189-825 more, LC). CONCLUSIONS: PCCs probably provide an advantage in INR reversal compared to plasma. There was no added risk of adverse events with PCCs.

Current advances in transfusion medicine 2021: A critical review of selected topics by the AABB Clinical Transfusion Medicine Committee.

BACKGROUND: Each year the AABB Clinical Transfusion Medicine Committee (CTMC) procures a synopsis highlighting new, important, and clinically relevant studies in the field of transfusion medicine (TM). This has been made available as a publication in Transfusion since 2018. METHODS: CTMC members reviewed and identified original manuscripts covering TM-related topics published electronically (ahead-of-print) or in print from December 2020 to December 2021. Selection of publications was discussed at committee meetings and chosen based on perceived relevance and originality. Next, committee members worked in pairs to create a synopsis of each topic, which was then reviewed by additional committee members. The first and senior authors assembled the final manuscript. Although this synopsis is extensive, it is not exhaustive, and some articles may have been excluded or missed. RESULTS: The following topics are included: blood products; convalescent plasma; donor collections and testing; hemoglobinopathies; immunohematology and genomics; hemostasis; patient blood management; pediatrics; therapeutic apheresis; and cell therapy. CONCLUSIONS: This synopsis highlights and summarizes recent key developments in TM and may be useful for educational purposes.

Comparative risk of pulmonary adverse events with transfusion of pathogen reduced and conventional platelet components.

BACKGROUND: Platelet transfusion carries risk of transfusion-transmitted infection (TTI). Pathogen reduction of platelet components (PRPC) is designed to reduce TTI. Pulmonary adverse events (AEs), including transfusion-related acute lung injury and acute respiratory distress syndrome (ARDS) occur with platelet transfusion. STUDY DESIGN: An open label, sequential cohort study of transfusion-dependent hematology-oncology patients was conducted to compare pulmonary safety of PRPC with conventional PC (CPC). The primary outcome was the incidence of treatment-emergent assisted mechanical ventilation (TEAMV) by non-inferiority. Secondary outcomes included: time to TEAMV, ARDS, pulmonary AEs, peri-transfusion AE, hemorrhagic AE, transfusion reactions (TRs), PC and red blood cell (RBC) use, and mortality. RESULTS: By modified intent-to-treat (mITT), 1068 patients received 5277 PRPC and 1223 patients received 5487 CPC. The cohorts had similar demographics, primary disease, and primary therapy. PRPC were non-inferior to CPC for TEAMV (treatment difference -1.7%, 95% CI: (-3.3% to -0.1%); odds ratio = 0.53, 95% CI: (0.30, 0.94). The cumulative incidence of TEAMV for PRPC (2.9%) was significantly less than CPC (4.6%, p = .039). The incidence of ARDS was less, but not significantly different, for PRPC (1.0% vs. 1.8%, p = .151; odds ratio = 0.57, 95% CI: (0.27, 1.18). AE, pulmonary AE, and mortality were not different between cohorts. TRs were similar for PRPC and CPC (8.3% vs. 9.7%, p = .256); and allergic TR were significantly less with PRPC (p = .006). PC and RBC use were not increased with PRPC. DISCUSSION: PRPC demonstrated reduced TEAMV with no excess treatment-related pulmonary morbidity.

Comparison of prenatal anti-D titration testing by gel and tube methods: A review of the literature.

BACKGROUND: Antenatal titration testing is traditionally performed using a manual tube test. Tube testing has limitations; it is a manual, time-consuming method with wide interobserver variability. Gel-based testing is an attractive alternative because it is more precise and can be automated. This study's objective was to summarize the published literature that assessed the relationship between titrations performed by tube and gel for anti-D alloimmunized pregnancies. STUDY DESIGN AND METHODS: A comprehensive literature search was performed. Articles were selected if research was original and compared at least five pairs of anti-D titration tests performed by gel and tube. Differences in the number of dilutions between gel and tube methods were compared overall by study and cell type using linear models. RESULTS: A total of 512 articles were identified; eight were included, and titer data from 384 tube and gel pairs were abstracted. The median anti-D titer in tube was 8 (range 0-2048) and by gel was 64 (range 0-4096). Anti-D gel titration results were 2.1 (95% CI; 1-3.3) additional dilutions greater than in tube. Most studies utilized double-dose reagent cells for testing. At a tube titer of 16, the sensitivity and specificity of gel titrations is maximal (91% and 94% respectively) at a gel titer of 64. CONCLUSION: Overall, titrations performed by gel were two dilutions higher than the corresponding tube titer. For titrations, double-dose reagent cells should be considered to standardize practice. A rigorous prospective study is needed to compare tube titrations with gel titrations using a standardized process.

Limitations of current practices in detection of bacterially contaminated blood products associated with suspected septic transfusion reactions.

BACKGROUND: In the setting of suspected septic transfusion reactions, bacterial culture of both the transfused patient and the residual blood component is recommended. Primary bacterial contamination can occur at the time of component collection. Clinically insignificant "secondary contamination" can occur during post-transfusion component discard, retrieval for culture, or manipulation of the bag at the time of culture sampling. STUDY DESIGN AND METHODS: This retrospective, multi-center study analyzes positive residual component culture results and companion patient blood cultures from 15 hospitals, 1 blood center, and all cultured transfusion reactions within the province of Quebec, Canada, over a 5-year period. Imputability was assigned as "definite" (concordant growth), "possible" (discordant growth or lack of growth in patient culture), or "unable to assess" (patient not cultured). RESULTS: There were 373 positive component cultures from 360 unique transfusion reactions, with 276 (76.7%) companion patient blood cultures performed, of which 10 (2.8%) yielded the pathogen detected in the positive component. Of these 10 definite pathogens, 7 (2 Staphylococcus aureus, 3 other staphylococci, and 1 Streptococcus pyogenes and 1 Bacillus sp.) were associated with platelet and 3 (Aeromonas veronii, Staphylococcus epidermidis, and Enterococcus faecalis) with RBC transfusions. RBC and plasma components comprised 70% of positive component cultures. DISCUSSION: The process of performing residual component culture is vulnerable to secondary contamination. The significance of microorganisms recovered from component culture cannot be interpreted in isolation. In the context of low prevalence of primary contamination of blood components, the positive predictive value of a positive component culture result is very low.

Hospital transfusion service operations during the SARS-CoV-2 pandemic: Lessons learned from the AABB hospital survey in preparation for the next infectious disease outbreak.

BACKGROUND: The SARS-CoV-2 pandemic disrupted hospital operations, affected the blood supply, and challenged the health care system to develop new therapeutic options, including convalescent plasma (CCP). The aim of this study is to describe and analyze blood supply fluctuations and the use of convalescent plasma in 2020. METHODS: AABB distributed a weekly and biweekly questionnaire through email to hospital-based members (HBM). RESULTS: The survey was sent to 887 HBM with 479 unique respondents, most of the hospitals served pediatric and adult patients, and all states of the country participated, except Idaho and Vermont. Fifty four percent of HBM reported increased wastage in the early phase of the pandemic (May), which decreased to 4% by the end of June and throughout the rest of the year. The majority of HBM reported receiving alerts from their blood suppliers reporting blood shortages throughout the year. During March and April, only 12% of HBM were performing elective surgical procedures. The top reasons to delay procedures were: bed availability (28%); COVID-19 caseload (23%; and blood availability (19%). By mid-April, 42% HBM had transfused CCP and reported >24 h delay in getting the units; the vast majority obtained CCP using the Expanded Access Protocol, and later, the Emergency Use Authorization. HBM consistently prioritized the most severe patients to receive CCP, but the proportion of severely ill recipients fell from 52% to 37% between May and October, with an increase from 5% to 21% of HBM providing CCP transfusion early in the course of the disease. DISCUSSION: Blood utilization and availability fluctuated during the pandemic. The fluctuations appeared to be related to the number of COVID-19 in the community. The use and regulatory landscape of CCP rapidly evolved over the first 8 months of the pandemic.

A survey of US hospitals on platelet inventory management, transfusion practice, and platelet availability.

BACKGROUND: A survey of US hospitals was conducted to increase our understanding of the current state of platelet (PLT) practice and supply. The survey captures information on transfusion practice and inventory management, including stock levels, outdate rates, ability to return or transfer PLTs, and low dose PLTs. Notably, the survey also elucidates PLT availability challenges and impact to patient care. STUDY DESIGN AND METHODS: A 27 question online survey was distributed directly to over 995 US hospitals and indirectly through blood centers to many more between September 27 and October 25, 2019. Descriptive statistics were used for respondent characteristics. Bivariate analysis was performed and correlation coefficients, chi square tests, and p values determined statistical significance of relationships between variables. RESULTS: Four hundred and eighty-one hospitals completed the survey of which 21.6%, 53.2%, and 25.2% were characterized as small, medium, and large hospitals, respectively. Some key observations from this survey include: (1) there is an opportunity for greater adherence to evidence-based guidelines; (2) higher outdate rates occur in hospitals stocking less than five PLTs and the ability to return or transfer PLTs lowers outdates; (3) use of low dose apheresis PLTs varies; and (4) decreased PLT availability is commonly reported, especially in hospitals with high usage, and can lead to delays in transfusions or surgeries. CONCLUSION: This survey represents a comprehensive national assessment of inventory management practices and PLT availability challenges in US hospitals. Findings from this survey can be used to guide further research, help shape future guidance for industry, and assist with policy decisions.

Current advances in transfusion medicine 2020: A critical review of selected topics by the AABB Clinical Transfusion Medicine Committee.

BACKGROUND: The AABB Clinical Transfusion Medicine Committee (CTMC) compiles an annual synopsis of the published literature covering important developments in the field of transfusion medicine (TM), which has been made available as a manuscript published in Transfusion since 2018. METHODS: CTMC committee members reviewed original manuscripts including TM-related topics published electronically (ahead) or in print from December 2019 to December 2020. The selection of topics and manuscripts was discussed at committee meetings and chosen based on relevance and originality. Next, committee members worked in pairs to create a synopsis of each topic, which was then reviewed by two additional committee members. The first and senior authors of this manuscript assembled the final manuscript. Although this synopsis is extensive, it is not exhaustive, and some papers may have been excluded or missed. RESULTS: The following topics are included: COVID-19 effects on the blood supply and regulatory landscape, COVID convalescent plasma, adult transfusion practices, whole blood, molecular immunohematology, pediatric TM, cellular therapy, and apheresis medicine. CONCLUSIONS: This synopsis provides easy access to relevant topics and may be useful as an educational tool.

Current advances in transfusion medicine: a 2019 review of selected topics from the AABB Clinical Transfusion Medicine Committee.

BACKGROUND: The AABB Clinical Transfusion Medicine Committee (CTMC) compiles an annual synopsis of the published literature covering important developments in the field of transfusion medicine (TM) for the board of director's review. This synopsis is now made available as a manuscript published in TRANSFUSION. STUDY DESIGN AND METHODS: CTMC committee members review original manuscripts including TM-related topics published in different journals between late 2018 and 2019. The selection of topics and manuscripts are discussed at committee meetings and are chosen based on relevance and originality. After the topics and manuscripts are selected, committee members work in pairs to create a synopsis of the topics, which is then reviewed by two committee members. The first and senior authors of this manuscript assembled the final manuscript. Although this synopsis is comprehensive, it is not exhaustive, and some papers may have been excluded or missed. RESULTS: The following topics are included: infectious risks to the blood supply, iron donor studies, pre-transfusion testing interference and genotyping, cold agglutinin disease (CAD), HLA alloimmunization in platelet transfusions, patient blood management, updates to TACO and TRALI definitions, pediatric TM, and advances in apheresis medicine. CONCLUSION: This synopsis provides easy access to relevant topics and may be useful as an educational tool.

The effect of serum pretreatment regimens for the detection of HLA class I antibodies in platelet-refractory patients.

BACKGROUND: Single antigen bead (SAB) assays are used to identify human leukocyte antigen (HLA) antibodies in patients with platelet refractoriness due to HLA Class I alloimmunization. Some laboratories use serum pretreatment regimens to eliminate interference from immunoglobulin M antibodies and complement. These modifications may contribute to interlaboratory variability, which is a recognized problem with the SAB assay. STUDY DESIGN AND METHODS: Five patients' sera were overnight shipped to 12 laboratories in the United States and internationally. Recipients used their lab's SAB procedure to identify HLA Class I antibodies. The resultant mean fluorescence intensity (MFI) data were compared by instrumentation, bead lot, and pretreatment regimens. Laboratory-specific cutoffs for positive antibodies were applied to the results. RESULTS: Interlaboratory variability for MFI values appears to be associated with different pretreatment regimens. The coefficient of variation (CV) of MFI from samples pretreated with ethylenediaminetetraacetic acid, dithiothreitol, or heat inactivation (EDHI) were similar, ranging from 14% to 56% (mean, 22%). For samples with no pretreatment, the CVs were significantly higher than EDHI-treated samples, ranging from 25% to 74% (mean, 39%; 95% confidence interval, 12.10-21.90; p < 0.0001). An intralaboratory comparison of pretreatment regimens confirmed these findings. Some positive antibody specificities present in EDHI-treated samples were negative in corresponding samples with no pretreatment when laboratory-specific cutoffs for positive antibodies were applied. CONCLUSION: Our results show that greater interlaboratory precision can be achieved when samples are pretreated with EDHI as opposed to no pretreatment, likely because these pretreatments eliminate interference from inhibitors. Inhibitors may mask antibodies, leading to missed (or uncalled) specificities when no pretreatment is used.

An exploration of the advantages of automated titration testing: low inter-instrument variability and equivalent accuracy for ABO and non-ABO antibody titres relative to tube testing.

BACKGROUND AND OBJECTIVES: Obtaining IgM and IgG titres is important in numerous clinical situations, including solid-organ transplant, obstetrics, and for testing of out-of-group plasma-containing components. Tube method is the most prevalent testing modality, though it is both labour-intensive and known for intra- and inter-laboratory variability. The utility of automated gel testing as a method to improve both inter- and intra-laboratory reproducibility is unknown. MATERIALS AND METHODS: Two academic centres participated in a study evaluating automated gel titreing. Group O plasma samples were used to measure titres of antibodies against ABO (IgM) with buffered gel cards and 4 minor and minor red-blood-cell antigens (IgG) anti-IgG gel cards. Multiple ORTHO VISION automated analyzers were used to assess inter-instrument variation. A subset of ABO (IgM) samples were compared between laboratories to evaluate inter-laboratory variability. Multiple samples were titred by tube and by automated gel technology to determine similarity of results. RESULTS: Testing demonstrated no significant difference between analysers or between sites when performing automated titrations (P ≥ 0·99). Non-ABO IgG titres were evaluated and demonstrated little inter-instrument variability. The IgM anti-A and -B titres obtained by automated gel testing were neither consistently higher nor lower than tube titres. Greater than 90% of titre values were within one dilution. CONCLUSION: Based on this study, our data suggest that titreing by automated gel testing is both highly reproducible (IgM and IgG) and does not differ significantly from manual tube testing results of direct agglutination (IgM).

Red-blood-cell alloimmunization and prophylactic antigen matching for transfusion in patients with warm autoantibodies.

BACKGROUND: Warm autoantibodies (WAA) are antibodies that react with an antigen on a patient's own red-blood-cells and can complicate compatibility testing whether or not they cause clinical haemolysis. The goal of this study was to understand the overall prevalence of WAA, the risk of RBC alloimmunization and determine whether RBC selection practices have an impact on alloimmunization. MATERIALS AND METHODS: Records of patients (>1 year of age) with an indirect antibody detection test (IAT) and serologic evidence of WAA over a 10-year-period were included. Eight centres from 5 countries collectively reviewed 1 122 245 patients who had an IAT. RESULTS: Of patients having IAT, 1214 had WAA (0·17%). Transfusion information for 1002 of the patients was available; 631 were transfused after identification of the WAA (63%); of the transfused patients, 390 received prophylactic antigen-matched (PAM) RBCs and 241 did not. Of the 372 patients with WAA who were transfused and had serologic testing 30+ days following transfusion (30-2765 days), 56 developed new RBC alloimmunization (15·1%). Patients who were transfused using a PAM strategy were not protected from new RBC alloimmunization [14·6% (31 of 212 patients) having PAM transfusion approach compared with those not receiving PAM approach (15·6%, 25 of 160 patients, P = 0·8837)]. CONCLUSIONS: The prevalence of WAA in patients having an IAT is low (<1%). A significant portion of patients with WAA form new RBC alloimmunization (15·1%); however, the use of PAM approach for RBC selection was not found to be protective against new alloimmunization.

Pathogen reduced plasma products: a clinical practice scientific review from the AABB.

BACKGROUND: A small body of literature assessing the efficacy and safety of pathogen reduced (PR) plasma has been published. STUDY DESIGN AND METHODS: An AABB committee systematically reviewed the literature and graded the clinical trial evidence with the assistance of a GRADE expert. RESULTS: Most studies identified were low quality and had a small sample size; in addition, efficacy and safety were monitored in many different ways making it difficult to quantify therapeutic benefit and risk. The data analyzed in this systematic review showed that pathogen inactivation did not adversely affect the efficacy of S/D or amotosalen plasma transfusions in any patient population studied. In addition, there were no significant safety issues for these patient populations, other than the specific contraindications noted in their respective package inserts. CONCLUSION: Larger, well-designed trials are needed to further evaluate the efficacy and safety of all of the PR plasma products.