Red blood cell alloantibodies in the context of critical bleeding and massive transfusion

BACKGROUND

In the context of critical bleeding and massive transfusion (CB/MT), little is known about the development of new red blood cell (RBC) alloantibodies. We performed a retrospective, observational study to examine the frequency of RBC alloantibodies (pre-existent, anamnestic, or new) in patients with CB/MT, defined as transfusion of five or more RBC units in any 4-hour period, for any cause of CB.

MATERIALS AND METHODS

Data on 2,585 New Zealand patients (date/time of MT initiation, demographic data, blood group, clinical context, and transfused RBCs) were obtained from the Australian and New Zealand Massive Transfusion Registry. RBC alloantibody screening/identification data were extracted from the New Zealand Blood Service database. We calculated summary statistics, compared proportions between different independent groups using the Chi-squared test, and performed logistic regression analysis to examine the effects of variables on alloantibody presence or formation. We also determined the immunogenicities of selected RBC antigens in the context of CB/MT.

RESULTS

Of 1,234 assessable patients, 1,166 (94.5%) showed no evidence of any alloantibody. Pre-existent, anamnestic, and new alloantibodies were found, respectively, in 4.3%, 0.4%, and 7.2% of assessable patients. By multivariable regression analysis, transfusion of D-positive RBC to D-negative patients was independently associated with new alloantibody formation. Neither the quantum of RBC transfused nor trauma as clinical context were so associated although the latter trended towards a predisposition. "Antibodies of undetermined specificity" were the commonest pre-existent and new alloantibodies. The immunogenicity of Jka was the highest in this setting.

DISCUSSION

RBC alloantibodies of any type were rare in this CB/MT population. Patients undergoing CB/MT appear to have low risks of re-stimulating anamnestic alloantibodies, or of developing new RBC alloantibodies.

Postnatal treatment for children with fetal and neonatal alloimmune thrombocytopenia: a multicentre, retrospective, cohort study

BACKGROUND

Children affected by fetal and neonatal alloimmune thrombocytopenia (FNAIT) are at risk of severe intracranial haemorrhage. Management in the postnatal period is based on sparse evidence. We aimed to describe the contemporary management and outcomes of patients with FNAIT in high-income countries.

METHODS

In this multicentre, retrospective, cohort study, we set up a web-based registry for the collection of deidentified data on the management and course of neonates with FNAIT. Eight centres from seven countries (Australia, Norway, Slovenia, Spain, Sweden, the Netherlands, and the USA) participated. Eligibility criteria comprised neonates with FNAIT being liveborn between Jan 1, 2010, and Jan 1, 2020; anti-human platelet antigen (HPA) alloantibodies in maternal serum; confirmed maternal and fetal HPA incompatibility; and bleeding detected at antenatal ultrasound, neonatal thrombocytopenia (<150 × 10⁹ platelets per L), or both in the current or previous pregnancy. Clinical data were retrieved from local medical records of the first neonatal admission and entered in the registry. The key outcome was the type of postnatal treatment given to neonates with FNAIT. Other outcomes were daily median platelet counts in the first week of life, median platelet count increment after first unmatched versus first matched transfusions, and the proportion of neonates with mild or severe bleeding.

FINDINGS

408 liveborn neonates with FNAIT were entered into the FNAIT registry, of whom 389 from Australia (n=74), Norway (n=56), Slovenia (n=19), Spain (n=55), Sweden (n=31), the Netherlands (n=138), and the USA (n=16) were included in our analyses. The median follow-up was 5 days (IQR 2-9). More neonates were male (241 [64%] of 379) than female (138 [36%]). Severe thrombocytopenia (platelet count <50 × 10⁹ platelets per L) was reported in 283 (74%) of 380 neonates, and extreme thrombocytopenia (<10 × 10⁹ platelets per L) was reported in 92 (24%) neonates. Postnatal platelet count nadir was higher in the no-treatment group than in all other groups. 163 (42%) of 389 neonates with FNAIT received no postnatal treatment. 207 (53%) neonates received platelet transfusions, which were either HPA-unmatched (88 [43%] of 207), HPA-matched (84 [41%]), or a combination of both (35 [17%]). The proportion of neonates who received HPA-matched platelet transfusions varied between countries, ranging from 0% (Slovenia) to 63% (35 of 56 neonates; Norway). Postnatal intravenous immunoglobulin treatment was given to 110 (28%) of 389 neonates (alone [n=19] or in combination with platelet transfusions [n=91]), with the proportion receiving it ranging from 12% (17 of 138 neonates; the Netherlands) to 63% (ten of 16 neonates; the USA) across countries. The median platelet increment was 59 × 10⁹ platelets per L (IQR 35-94) after HPA-unmatched platelet transfusions and 98 × 10⁹ platelets per L (67-134) after HPA-matched platelet transfusions (p<0·0001). Severe bleeding was diagnosed in 23 (6%) of 389 liveborn neonates, with one having a severe pulmonary haemorrhage and 22 having severe intracranial haemorrhages. Mild bleeding was diagnosed in 186 (48%) neonates.

INTERPRETATION

Postnatal management of FNAIT varies greatly between international centres, highlighting the absence of consensus on optimal treatments. Our data suggest that HPA-matched transfusions lead to a larger median platelet count increment than HPA-unmatched transfusions, but whether HPA matching is also associated with a reduced risk of bleeding remains unknown.

FUNDING

Sanquin.

Age of red blood cells is not associated with in-hospital mortality in massively transfused patients

BACKGROUND

Studies comparing mortality following massive transfusion (MT) with fresher versus longer-stored red blood cells (RBCs) have focused on trauma patients. The Australian and New Zealand Massive Transfusion Registry collects data on all adult MT cases (≥5 RBCs within 4 hours, any bleeding context, ≥18 years) at participating hospitals.

METHODS

Years 2007 to 2018 data from 29 hospitals were analyzed to quantify the association between mortality and RBC storage time in adult MT cases. We ran three logistic regression models separately on each of seven bleeding contexts, with in-hospital mortality as the outcome and, in turn, (1) mean storage time (STmean) quartiles, (2) proportion of RBCs ≥30 days old (propOLD), and (3) scalar age of blood index as predictors.

RESULTS

A total of 8,685 adult MT cases involving transfusion of 126,622 RBCs were analyzed with Australian and New Zealand data analyzed separately. Mean storage times for these cases were (by quartile in ascending order) as follows: Australia, 12.5 days (range, 3.1-15.5 days), 17.7 (15.5-19.9), 22.3 (19.9-24.9), and 29.8 (24.9-41.7); New Zealand, 11.3 days (3.6-13.7), 15.3 (13.7-16.8), 18.7 (16.8-20.7), and 24.5 (20.7-35.6). The odds ratios comparing in-hospital mortality for each quartile with that of the control first quartile (freshest blood), proportion of longer-stored (≥30 days) RBCs, and scalar age of blood index were not statistically significant across all bleeding contexts.

CONCLUSION

We find no correlation between in-hospital mortality and storage time of transfused RBCs in a large cohort of adult MT patients representing all bleeding contexts. These results are consistent with those of recent large multicenter trials.

LEVEL OF EVIDENCE

Epidemiologic, level III; Therapeutic, level IV.

Is Platelet Expiring Out of Date? A Systematic Review

Current platelet concentrates are perishable blood products with short shelf lives. Combined with often unpredictable demand, this results in platelet inventory management problems, manifested by high rates of outdating frequently reported at 10% to 20%, and sometimes inadequate clinical supply. The objective of this study was to critically review the published methodologies on measures to reduce platelet outdating rates, in order to determine how platelet outdating and availability can be improved. We performed a systematic review of journal articles published in English to May 2019 identified from MEDLINE, with reported methods to improve platelet inventory outdating rates and availability. The complexity of each methodology was scored based on whether a typical blood bank manager could design, implement and run a platelet outdating program based on the methodology. Twenty-four relevant citations were found-these included 8 citations employing operational research (OR) methodologies, 7 evaluation/best practice, 6 simulation and 3 forecasting. Over half the included studies have been published within the last decade. The citations reporting the lowest predicted outdating were also the most complex methods. Overall predicted outdating and shortages were less than 4% based on the available data. In conclusion, we found that research interest in platelet inventory management problems has increased in line with platelet demand and methods to assist in reducing outdating rates without increased shortages have been available now for 4 decades; high rates of platelet outdating do however continue to be reported around the world. Developments in platelet preparation and storage, and other new approaches, may assist in addressing this problem.

A time-driven, activity-based costing methodology for determining the costs of red blood cell transfusion in patients with beta thalassaemia major

OBJECTIVES

To describe the methodology to estimate the total cost of administration of a single unit of red blood cells (RBC) in adults with beta thalassaemia major in an Australian specialist haemoglobinopathy centre.

BACKGROUND

Beta thalassaemia major is a genetic disorder of haemoglobin associated with multiple end-organ complications and typically requiring lifelong RBC transfusion therapy. New therapeutic agents are becoming available based on advances in understanding of the disorder and its consequences. Assessment of the true total cost of transfusion, incorporating both product and activity costs, is required in order to evaluate the benefits and costs of these new therapies.

METHODS

We describe the bottom-up, time-driven, activity-based costing methodology used to develop process maps to provide a step-by-step outline of the entire transfusion pathway. Detailed flowcharts for each process are described. Direct observations and timing of the process maps document all activities, resources, staff, equipment and consumables in detail. The analysis will include costs associated with performing these processes, including resources and consumables. Sensitivity analyses will be performed to determine the impact of different staffing levels, timings and probabilities associated with performing different tasks.

RESULTS

Thirty-one process maps have been developed, with over 600 individual activities requiring multiple timings. These will be used for future detailed cost analyses.

CONCLUSIONS

Detailed process maps using bottom-up, time-driven, activity-based costing for determining the cost of RBC transfusion in thalassaemia major have been developed. These could be adapted for wider use to understand and compare the costs and complexities of transfusion in other settings.

Appropriateness of transfusions of red cells, platelets and fresh frozen plasma. An audit in a tertiary care teaching hospital

OBJECTIVE

To determine how current hospital practice for transfusions of red cells, platelets and fresh frozen plasma conformed with published criteria.

DESIGN

Elaboration of criteria for transfusion from a review of the current literature; and analysis of the medical records of patients receiving transfusions of red cells (200), platelets (215), and fresh frozen plasma (260) during defined time periods in 1993.

SETTING

A large tertiary care teaching hospital.

OUTCOME MEASURES

Inappropriateness rates for transfusion episodes and numbers of individual units of blood products administered.

RESULTS

Inappropriateness rates for transfusion episodes and numbers of individual units administered were 16% and 10% for red cells, 13% and 11% for platelets, and 24% and 16% for fresh frozen plasma (31% and 21% when transfusions for thrombotic thrombocytopenic purpura were excluded). Red cells and fresh frozen plasma were used inappropriately most frequently in association with a surgical procedure; for platelets, it was their use for bleeding. In many of the transfusions deemed inappropriate, deficiencies of red cells, platelets and/or coagulation factors were documented, but the degree of deficiency did not meet the stringent appropriateness criteria. Twenty-six transfusions were deemed inappropriate because the indication was not documented in the medical record.

CONCLUSIONS

Specific problem areas in which blood product use was inappropriate were identified. Guidelines for transfusion appropriateness, education of hospital staff, and a monitoring system to ensure adherence to the guidelines, are required.