Immunohematologic tolerance of chronic transfusion exchanges with erythrocytapheresis in sickle cell disease

Automated red blood cell exchange with a post-procedure haematocrit targeted at 34% in the chronic management of sickle cell disease

Optimal targets for red blood cell exchange (RCE) are not well defined in the chronic management of sickle cell disease. We analysed transfusion requirements and iron-related outcomes in 101 patients on chronic RCE with a post-procedure haematocrit (Ht) targeted at 34%, which is higher than typically used. A majority were of HbSS/HbSβ0 genotype (n = 72) and enrolled for neurological complications (n = 53). Fifty patients had a positive Ht balance with RCE (>2% mean increase from pre-procedure level), while 43 patients maintained a neutral balance. The first group required fewer red blood cell units/year (65 vs. 80, p < 0.001), but a significant proportion were iron overloaded based on R2* with liver MRI (32% vs. none performed) and prescription of iron chelation (52% vs. 0%, p < 0.001, after a median of 19 months). The second group was more likely to receive iron supplementation (6% vs. 56%, p < 0.001). Chronic automated RCE with a post-procedure Ht targeted at 34% is not iron-neutral, and personalized Ht goals may be more appropriate in certain settings. This higher target should be compared with a lower Ht strategy in individuals with similar baseline red cell volumes to assess iron homeostasis and blood product requirements.

Prophylactic exchange transfusion in sickle cell disease pregnancy: a TAPS2 feasibility randomized controlled trial

ABSTRACT

Serial prophylactic exchange blood transfusion (SPEBT) is increasingly used in sickle cell disease (SCD) pregnancy, despite a lack of robust evidence. The Transfusion Antenatally in Pregnant Women with Sickle Cell Disease (TAPS2) study assessed the feasibility and acceptability of conducting a definitive randomized controlled trial of SPEBT (intervention) vs standard care (control) in this population. Women aged ≥18 years with SCD, between 6+0 and 18+6 weeks of singleton gestation, were randomized 1:1 every 6 -10 weeks throughout pregnancy in 7 hospitals in England. The main outcomes were recruitment rate (primary outcome), acceptability, and retention. Secondary outcomes were safety and maternal/infant outcomes. In total, 194 women were screened over 42 months (extended because of the pandemic), 88 were eligible, and 35 (39.8%) consented to participate; 18 participants were randomized to intervention, and 17 to control. Follow-up data were collected on all participants. Twelve patients in the intervention group received at least 1 SPEBT, of these, 11 received ≥3. The remaining patient was withdrawn from SPEBT because of transfusion reaction. Sixteen control participants required at least 1 transfusion. There were no statistically significant differences in maternal, infant, and postnatal outcomes. A trend toward a lower incidence of vaso-occlusive crisis, preterm delivery, and improved birthweight was observed in the intervention. The study achieved satisfactory recruitment and retention, confirming its acceptability to participants. TAPS2 demonstrates that it is feasible to perform a definitive international trial of SPEBT in SCD pregnancy. These trials were registered at www.ClinicalTrials.gov as #NCT03975894 and International Standard Randomized Controlled Trial Number (www.isrctn.com; #ISRCTN52684446).

Logistics, risks, and benefits of automated red blood cell exchange for patients with sickle cell disease

Red blood cell (RBC) transfusions treat and prevent severe complications of sickle cell disease (SCD) and can be delivered as a simple or exchange transfusion. During an exchange, some of the patient's abnormal hemoglobin (Hb) S (HbS) RBCs are removed. An apheresis device can accomplish an automated RBC exchange, simultaneously removing patient's RBCs while returning other blood components along with normal RBCs. Automated RBC exchange is therefore an isovolemic transfusion that can efficiently decrease HbS RBCs while limiting iron loading and hyperviscosity. However, specialized equipment, trained personnel, appropriate vascular access, and increased RBC exposure are required compared to simple or manual RBC exchange. Therefore, risks and benefits must be balanced to make individualized decisions for patients with SCD who require transfusion.

Extended phenotyping does not preclude the occurrence of delayed haemolytic transfusion reactions in sickle cell disease

Delayed haemolytic transfusion reaction (DHTR) is a potentially life-threatening complication of red blood cell (RBC) transfusions in sickle cell disease (SCD) and is classically induced by reactivation of previously formed antibodies. Improved antigenic matching has reduced alloimmunization and may reduce DHTR risk. We conducted a retrospective cohort study to investigate the incidence rate of DHTR in SCD patients receiving extended matched units (ABO/RhDCcEe/K/Fy^a /Jk^b /S). Occasional transfusion episodes (OTE) between 2011 and 2020 were reviewed for occurrence of DHTR symptoms using four screening criteria: decreased Hb, increased lactate dehydrogenase (LDH), pain, and dark urine. We included 205 patients who received a cumulative number of 580 transfusion episodes of 1866 RBC units. During follow-up, 10 DHTR events were observed. The incidence rate of DHTR was 13·8/1000 OTEs [95% confidence interval (CI): 7·37-22·2], with a cumulative incidence of 15·2% (95% CI: 8·4-24·0%) after 25 patients having received RBC units. One DHTR event was fatal (10%). Symptoms were misdiagnosed in four DHTR events (40%) as other acute SCD complications. Despite a lower incidence rate compared to most other studies, the incidence rate of DHTR in SCD remains high, in spite of extended matching of donor RBCs. Increased awareness of DHTR is of utmost importance to facilitate early diagnosis and, consequently, improve outcome.

Anti-D alloimmunization in Rh(D) negative adults with severe traumatic injury

INTRODUCTION

Widely varying rates of alloimmunization associated with transfusing uncrossmatched RBC products to trauma patients as part of hemostatic resuscitation have been reported. We characterized the rates of RBC alloimmunization in our severely injured Rh(D) negative trauma population who received uncrossmatched Rh(D) positive RBC products.

METHODS

In a 10-year retrospective analysis to assess Rh(D) alloimmunization risks, Rh(D) negative adult trauma patients initially requiring uncrossmatched group O Rh(D) positive RBC products with either RBC units or low titer group O whole blood as part of massive transfusion protocol (MTP) activation were identified. Only those Rh(D) negative patients whose initial antibody screenings were negative were included. Duration of serologic follow-up from date of MTP activation to either date of anti-D detection or most recent negative antibody screening was calculated.

RESULTS

There were 129 eligible Rh(D) negative trauma patients identified. Median injury severity score was 25. Anti-D was detected in 10 (7.8%) patients after a median of 161.5 days; the median duration of serologic follow-up in those who did not have anti-D detected was 220 days. Patients who had anti-D detected were less severely injured and received fewer Rh(D) positive RBC products versus those who did not.

DISCUSSION

In our severely injured adult trauma patients with MTP activation requiring uncrossmatched group O Rh(D) positive RBC products, the rate of anti-D detection was low. Additional studies are necessary to determine generalizability of these findings and fully characterize alloimmunization risks in trauma patients with varying extents of injury.

Automated Red Cell Exchange in the Management of Sickle Cell Disease

Red cell transfusion represents one of the cornerstones of the chronic management of sickle cell disease, as well as its acute complications. Automated red cell exchange can rapidly lower the number of circulating sickle erythrocytes, without causing iron overload. Here, we describe our experience, having offered this intervention since 2011. A transient reduction in the platelet count by 61% was observed after the procedure. This was not associated with any haemorrhagic complications. Despite exposure to large volumes of blood, the alloimmunisation rate was only 0.027/100 units of red cells. The absence of any iron loading was confirmed by serial Ferriscans, performed over a number of years. However, patients with advanced chronic kidney disease showed evidence of iron loading due to reduced innate haemopoiesis and were subsequently switched to simple transfusions. A total of 59% of patients were on regular automated red cell exchange with a history of recurrent painful crises. A total of 77% responded clinically, as evidenced by at least a 25% reduction in their emergency hospital attendance for pain management. The clinical response was gradual and increased the longer patients stayed on the program. The earliest sign of clinical response was a reduction in the length of stay when these patients were hospitalised, indicating that a reduction in the severity of crises precedes the reduction in their frequency. Automated red cell exchange also appeared to be beneficial for patients with recurrent leg ulcers and severe, drug resistant stuttering priapism, while patients with pulmonary hypertension showed a dramatic improvement in their symptoms as well as echocardiographic parameters.

Safety and benefits of automated red cell depletion-exchange compared to standard exchange in patients with sickle cell disease undergoing chronic transfusion

BACKGROUND

The Spectra Optia allows automated performance of red blood cell reduction and isovolemic hemodilution (IHD) prior to standard red cell exchange (RCE), and is primarily intended for patients with sickle cell disease (SCD) undergoing chronic RCE. Data on the safety of inducing transient further anemia and the benefits of IHD-RCE is limited and occasionally contradictory.

STUDY DESIGN AND METHODS

In this retrospective crossover analysis of six patients with SCD who underwent chronic exchange with standard RCE (Cobe Spectra) followed by IHD-RCE (Spectra Optia), we compared safety and benefit outcomes with IHD-RCE vs standard RCE.

RESULTS

There were statistically but not clinically significant drops in blood pressure in the post-IHD phase. With IHD-RCE, there were significant reductions in red blood cell (RBC) usage and/or lower fraction of cells and significant increases in postprocedure hematocrit (Hct) associated with increased preprocedure Hct. There were no differences achieved in the time interval between procedures or in the net RBC gain with IHD-RCE. Overall, there were also no significant differences in pre- and postprocedure percentage of hemoglobin S, reticulocyte count, interval daily hemoglobin A decrement, or postprocedure white blood cell, neutrophil, or platelet counts.

CONCLUSIONS

Our study supports that IHD-RCE can be safely used in patients with stroke risk and compared to standard RCE, results in benefits of lower RBC usage and/or fraction of cells remaining and higher postprocedure Hct associated with higher preprocedure Hct. These findings support wider use of IHD-RCE, especially in the current environment with reduced availability of minority units.

The cause and pathogenesis of hemolytic transfusion reactions in sickle-cell disease

PURPOSE OF REVIEW

The current review aims to summarize the epidemiology, cause, pathophysiology, and management of hemolytic transfusion reactions in sickle-cell disease (SCD).

RECENT FINDINGS

Patients undergoing occasional, isolated transfusions have been shown to have a higher risk of developing this condition. Despite the identification of well known risk factors, including alloimmunization, the pathophysiology of this syndrome remains unclear, as very severe forms with hyperhemolysis may develop in the absence of detectable antibodies, or with antibodies that are not considered to be clinically significant. Complement plays a crucial role in this reaction, particularly in cases of intravascular hemolysis. Complement triggers the reaction, but it also amplifies the inflammatory response and aggravates tissue damage. Free heme and hemoglobin are released and interact with complement, causing tissue damage.

SUMMARY

Hemolytic transfusion reactions are the most feared complications of blood transfusion in patients with SCD. This reaction is underdiagnosed because it mimics a vaso-occlusive crisis. Alloimmunization against red blood cell antigens is known to be a major trigger of this reaction, but abnormal complement activation and the underlying condition in patients with chronic hemolysis, may amplify the reaction. There is an urgent need to develop evidence-based approaches for preventing and treating this reaction.

Transfusion support in patients with sickle cell disease

Blood transfusions are an integral component of the management of acute and chronic complications of sickle cell disease. Red cells can be administered as a simple transfusion, part of a modified exchange procedure involving manual removal of autologous red cells and infusion of donor red cells, and part of an automated red cell exchange procedure using apheresis techniques. Individuals with sickle cell disease are at risk of multiple complications of blood transfusions, including transfusional hemosiderosis, auto- and alloimmunization to minor red cell and human leukocyte antigens, delayed hemolytic transfusion reactions, and hyper-hemolysis. In low- and middle-income countries in sub-Saharan Africa, where a directed donor system is prevalent and limited laboratory methods are in place to perform extended red cell phenotyping, leukodepletion of cellular products, and infectious disease screening, there are additional challenges to providing safe and adequate transfusion support for this patient population. We review current indications for acute and chronic transfusions in sickle cell disease that are derived primarily from randomized controlled trials and observational studies in children living in high-income countries. We will highlight populations with unique transfusion needs, such as pregnant women and children, as well as the role of the transfusion medicine consultative service for individuals with sickle cell disease planning to have curative hematopoietic stem cell transplantation or gene therapy. Finally, we will discuss risk factors for alloimmunization in individuals with sickle cell disease, emerging new strategies to prevent alloimmunization in this population, and critical gaps in the implementation of transfusion guidelines for sickle cell disease in high- and low-income countries.

American Society of Hematology 2020 guidelines for sickle cell disease: transfusion support

BACKGROUND

Red cell transfusions remain a mainstay of therapy for patients with sickle cell disease (SCD), but pose significant clinical challenges. Guidance for specific indications and administration of transfusion, as well as screening, prevention, and management of alloimmunization, delayed hemolytic transfusion reactions (DHTRs), and iron overload may improve outcomes.

OBJECTIVE

Our objective was to develop evidence-based guidelines to support patients, clinicians, and other healthcare professionals in their decisions about transfusion support for SCD and the management of transfusion-related complications.

METHODS

The American Society of Hematology formed a multidisciplinary panel that was balanced to minimize bias from conflicts of interest and that included a patient representative. The panel prioritized clinical questions and outcomes. The Mayo Clinic Evidence-Based Practice Research Program supported the guideline development process. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to form recommendations, which were subject to public comment.

RESULTS

The panel developed 10 recommendations focused on red cell antigen typing and matching, indications, and mode of administration (simple vs red cell exchange), as well as screening, prevention, and management of alloimmunization, DHTRs, and iron overload.

CONCLUSIONS

The majority of panel recommendations were conditional due to the paucity of direct, high-certainty evidence for outcomes of interest. Research priorities were identified, including prospective studies to understand the role of serologic vs genotypic red cell matching, the mechanism of HTRs resulting from specific alloantigens to inform therapy, the role and timing of regular transfusions during pregnancy for women, and the optimal treatment of transfusional iron overload in SCD.

Red Blood Cells: Exchange, Transfuse, or Deplete

Erythrocytapheresis, red blood cell (RBC) depletion, and RBC exchange transfusions are apheresis techniques used to rapidly lower the circulating RBC mass or to exchange the patient erythrocyte mass with donor RBC. Automated RBC exchange is performed using an apheresis device, while manual RBC exchange is based on sequential phlebotomies and isovolemic replacement. Compared to simple RBC transfusions, RBC exchange offers several advantages, e.g., a lower risk for iron accumulation and efficient control of pathological erythrocyte populations. Disadvantages are the higher costs of the procedure, the increased use of donor RBC, and the requirement of apheresis devices and trained hospital staff. The most frequent indication for RBC exchange is sickle cell disease (SCD). RBC exchange transfusions are standard treatment in SCD patients with a history of or a risk for acute stroke and are clinical options for other acute complications of SCD. The most common indication for RBC depletion is the removal of donor RBC from the bone marrow grafts in major ABO-incompatible allogeneic hematopoietic stem cell transplantation to avoid immediate hemolysis. Rare indications for RBC exchange are severe infections with intraerythrocytic pathogens such as malaria or babesiosis and severe erythrocytosis or hereditary hemochromatosis where the aim is to rapidly decrease RBC populations or the iron content. However, only few high-quality studies are available looking at the efficacy of RBC exchange in the different disease entities, and treatment is often based on low levels of evidence and should therefore be decided in close collaboration with a transfusion medicine specialist.

Guidelines on the Use of Therapeutic Apheresis in Clinical Practice - Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Eighth Special Issue

The American Society for Apheresis (ASFA) Journal of Clinical Apheresis (JCA) Special Issue Writing Committee is charged with reviewing, updating and categorizing indications for the evidence-based use of therapeutic apheresis (TA) in human disease. Since the 2007 JCA Special Issue (Fourth Edition), the committee has incorporated systematic review and evidence-based approaches in the grading and categorization of apheresis indications. This Eighth Edition of the JCA Special Issue continues to maintain this methodology and rigor in order to make recommendations on the use of apheresis in a wide variety of diseases/conditions. The JCA Eighth Edition, like its predecessor, continues to apply the category and grading system definitions in fact sheets. The general layout and concept of a fact sheet that was introduced in the Fourth Edition, has largely been maintained in this edition. Each fact sheet succinctly summarizes the evidence for the use of TA in a specific disease entity or medical condition. The Eighth Edition comprises 84 fact sheets for relevant diseases and medical conditions, with 157 graded and categorized indications and/or TA modalities. The Eighth Edition of the JCA Special Issue seeks to continue to serve as a key resource that guides the utilization of TA in the treatment of human disease.

Selecting red blood cell units to perform RBCX in patients with sickle cell disease

Red blood cell exchange (RBCX) is a standard option for treating or preventing complications in patients with sickle cell disease (SCD). According to the patient's blood volume, the amounts of red blood cells (RBC) to be exchanged and the practices of the apheresis and clinical teams, such treatment requires numerous red blood cell units (RBCUs) (3-15 RBCUs per procedure). To perform RBCXs safely and prevent the risk of alloimmunization, appropriate RBCUs must be selected and transfused to replace the sickled RBCs. Understanding of alloimmunization in patients with SCD strengthened the development of recommendations for preventing the risk of alloimmunization. This review describes the alloimmunization risk, the methods used to decrease the risk, and our own experience.

Recommendations for the use of red blood cell exchange in sickle cell disease

Sickle cell disease (SCD) is a genetic disorder characterised by a single mutation of the beta globin gene, causing the production of an abnormal haemoglobin called sickle haemoglobin (HbS). In its deoxygenated form, HbS polymerises, causing major rheological disorders, which presents clinically as periodic vaso-occlusive crises, chronic haemolysis and chronic vascular dysfunction. Patients often resort to a background treatment, and transfusion remains the cornerstone in the management of the disease, significantly reducing morbidity and mortality. The aim of red blood cell exchange (RBCX) is to improve tissue oxygenation by increasing haemoglobin levels while lowering HbS levels. RBCX can be performed by manual or automated exchange, and each technique has its own set of advantages and disadvantages. This article will outline the transfusion indications for the main complications of SCD, as well as the most appropriate strategy to use.

Complement activation during intravascular hemolysis: Implication for sickle cell disease and hemolytic transfusion reactions

Intravascular hemolysis is a hallmark of a large spectrum of diseases, including the sickle cell disease (SCD), and is characterized by liberation of red blood cell (RBC) degradation products in the circulation. Released Hb, heme, RBC fragments and microvesicles (MVs) exert pro-inflammatory, pro-oxidative and cytotoxic effects and contribute to vascular and tissue damage. The innate immune complement system not only contributes to the RBC lysis, but it is also itself activated by heme, RBC MVs and the hypoxia-altered endothelium, amplifying thus the cell and tissue damage. This review focuses on the implication of the complement system in hemolysis and hemolysis-mediated injuries in SCD and in cases of delayed hemolytic transfusion reactions (DHTR). We summarize the evidences for presence of biomarkers of complement activation in patients with SCD and the mechanisms of complement activation in DHTR. We discuss the role of antibodies-dependent activation of the classical complement pathway as well as the heme-dependent activation of the alternative pathway. Finally, we describe the available evidences for the efficacy of therapeutic blockade of complement in cases of DHTR. In conclusion, complement blockade is holding promises but future prospective studies are required to introduce Eculizumab or another upcoming complement therapeutic for DHTR and even in SCD.

Automatic depletion with Spectra Optia allows a safe 16% reduction of red blood cell pack consumption in exchanged sickle cell anemia patients

BACKGROUND

Chronic red blood cell exchanges (RBCXs) are frequently used to prevent complications in patients with sickle cell anemia, but the scarcity of matched red blood cell packs (RBCPs) is a serious concern. The main goal of this study was to compare the number of RBCPs used during RBCXs between the Spectra Optia (SO) device (with the automatic depletion step) and the former Cobe Spectra (CSP) device.

STUDY DESIGN AND METHODS

The performances and safety of 300 SO sessions using the automatic depletion step (SO/DE) in 50 patients with sickle cell anemia under a chronic transfusion program over a 1-year period were prospectively analyzed. The numbers of RBCPs saved using this protocol compared to the SO device without depletion and to the CSP device were determined.

RESULTS

The SO/DE protocol appeared to be safe, as only 5% and 17% of the sessions were characterized by a significant decrease in blood pressure and increase in heart rate (grade 2 adverse events), respectively. Postapheresis hematocrit and fraction of cells remaining reached expected values. The SO/DE protocol required 16% fewer RBCPs compared to SO without depletion, allowing a mean saving of 12 RBCPs per patient and per year and 13% fewer compared to CSP device. Interestingly, the saving was more important for patients with high total blood volume and/or high preapheresis hematocrit.

CONCLUSION

The SO/DE protocol is an efficient, safe and cost-effective procedure for patients with sickle cell anemia under a chronic transfusion program.

More efficient exchange of sickle red blood cells can be achieved by exchanging the densest red blood cells: An ex vivo proof of concept study

BACKGROUND

In sickle cell disease (SCD), red blood cells (RBCs) containing hemoglobin S can be denser than RBCs containing wild-type hemoglobin, especially when dehydrated. We hypothesize that targeting denser RBCs during red blood cell (RBC) exchange for SCD could result in more efficient removal of dehydrated, sickled RBCs and preservation of non-sickled RBCs.

STUDY DESIGN AND METHODS

Waste products from RBC exchanges for SCD were used as "simulated patients". One RBC volume was exchanged using ABO-compatible blood. The apheresis instrument was programmed to exchange the entire RBC layer by indicating the hematocrit (control), or the bottom half by indicating the hematocrit was half the hematocrit (experimental), with or without subsequent transfusion. Hemoglobin S levels, and complete blood counts were measured.

RESULTS

Hemoglobin S levels were lower after the modified versus control RBC exchange (post-RBC exchange mean 4.96% and 11.27%); total hemoglobin S amounts were also lower (mean 19.27 and 58.29 mL of RBCs). Mean RBC density decreased after the modified RBC exchange by 8.86%. Hematocrit decreased in the modified RBC exchange by 36.37%, with partial correction by direct transfusion following a truncated RBC exchange.

CONCLUSIONS

Targeting denser RBCs in RBC exchange enhanced hemoglobin S removal and decreased RBC density. Further development of this ex vivo model could potentially allow for: 1) improved reduction in hemoglobin S levels (allowing for longer periods between RBC exchange or maintained lower levels), or 2) achievement of previous goal hemoglobin S levels with fewer donor units (reducing alloimmunization risk and improving blood utilization).

Chronic blood exchange transfusions in the management of pre-capillary pulmonary hypertension complicating sickle cell disease

The long-term effects of chronic blood exchange transfusions (BETs) on pre-capillary pulmonary hypertension complicating sickle cell disease (SCD) are unknown.13 homozygous SS SCD patients suffering from pre-capillary pulmonary hypertension and treated by chronic BETs were evaluated retrospectively. Assessments included haemodynamics, New York Heart Association Functional Class (NYHA FC), 6-min walk distance (6MWD) and blood tests.Before initiating BETs, all patients were NYHA FC III or IV, median (range) 6MWD was 223 (0-501) m and median (range) pulmonary vascular resistance (PVR) was 3.7 (2-12.5) Wood Units. After a median number of 4 BET sessions, all patients had improved to NYHA FC II or III. Significant improvements in haemodynamics were observed, including a decrease in PVR (p=0.01). There was a trend to higher 6MWD (p=0.09). Median (range) follow-up time after initiation of BETs was 25 (6-53) months. During this period, two patients decided to stop BETs. One of them died from acute right heart failure and the other experienced worsening pulmonary hypertension. Two other patients died during follow-up at 25 and 54 months after BET initiation.Chronic BETs may be a potential therapeutic option in pre-capillary pulmonary hypertension complicating SCD, leading to significant clinical and haemodynamic improvements. These data must be confirmed in a prospective study.

Improvement of maternal and fetal outcomes in women with sickle cell disease treated with early prophylactic erythrocytapheresis

BACKGROUND

The desire for pregnancy in sickle cell disease (SCD) women has become a true challenge for hematologists, requiring a multidisciplinary approach. Erythrocytapheresis (ECP) is an important therapeutic tool in SCD, but only limited data on starting time and the effects of ECP during pregnancy are available.

STUDY DESIGN AND METHODS

This is a double-center retrospective cross-sectional study on a total of 46 single pregnancies in SCD women from January 2008 to June 2017. ECP was started at 10.7 ± 5.2 weeks of gestation, and prophylactic enoxaparin (4,000 U daily) was introduced due to the reported high prevalence of thromboembolic events in pregnant SCD women.

RESULTS

The alloimmunization ratio was 2.1 per 1,000 and the alloimmunization rate was 5.6%. In early ECP-treated SCD women, no severe vaso-occlusive crisis, sepsis or severe infection, or preeclampsia or eclampsia were observed. We found normal umbilical arterial impedance during pregnancy, suggesting an optimal uteroplacental function in early ECP-treated SCD women. This was also supported by the improvement in newborn birthweights compared to previous studies. In our cohort, three SCD women were started later on ECP (20-25 weeks), and gestation ended with late fetal loss. Placenta pathology documented SCD-related damage and erythroblasts in placental vessels, indicating fetal hypoxia.

CONCLUSIONS

Collectively, our data generate a rationale to support a larger clinical trial of early ECP program in SCD pregnancy.

The erythrocyte alloimmunisation in patients with sickle cell anaemia: a systematic review

Transfusion therapy is a common practice in the treatment of anaemia and can cause erythrocyte alloimmunisation. To systematise data related to erythrocyte alloimmunisation in patients with sickle cell disease (SCD), a bibliographic search was carried out in September 2017 to search for studies in four electronic databases. (i) Referring to the original work, (ii) being cohort or case-control, (iii) having been developed with individuals with SCD and (iv) having evaluated the erythrocyte alloimmunisation. Two reviewers identified the articles for inclusion in the study, extracted the predetermined data and carried out the evaluation of the methodological quality of the work. 21 studies were selected; the studies included data on 20 636 individuals (children and adults), were mostly published in the last 10 years, were developed in the United States and had high methodological quality. The occurrence of erythrocyte alloimmunisation ranged from 4·4 to 76%, and there was a higher rate of alloimmunisation against antigens of the Rh system. The risk factors for alloimmunisation were age; gender (female); red blood cell (RBC) units received; presence of ≥1 autoantibodies, TNF-α, interleukin (IL1B), human leukocyte antigens (HLA)-DRB1 gene polymorphisms; first blood transfusion (BT) after 5 years of age, transfusion episodic, multiple or during inflammatory events, acute chest syndrome (ACS) and vase-occlusive crisis (VOC); increased percentage of CD41 T memory cells; and positive direct antiglobulin test. Transfusion policies should be developed to protect the patient and his or her health based on the main factors associated with its incidence.

Transfusion in Haemoglobinopathies: Review and recommendations for local blood banks and transfusion services in Oman

Sickle cell disease and homozygous β-thalassaemia are common haemoglobinopathies in Oman, with many implications for local healthcare services. The transfusions of such patients take place in many hospitals throughout the country. Indications for blood transfusions require local recommendations and guidelines to ensure standardised levels of care. This article summarises existing transfusion guidelines for this group of patients and provides recommendations for blood banks and transfusion services in Oman. This information is especially pertinent to medical professionals and policy-makers developing required services for the standardised transfusion support of these patients.

Red blood cell alloimmunization in sickle cell disease: assessment of transfusion protocols during two time periods

BACKGROUND

Prevention of red blood cell (RBC) alloimmunization in patients with sickle cell disease (SCD) focuses on phenotypic RBC matching. We assessed alloimmunization among transfused patients with SCD after implementing leukoreduction and prophylactic antigen matching (PAM).

STUDY DESIGN AND METHODS

Retrospective review of transfusion and medical records for SCD patients 18 months to 81 years of age was performed covering two 5-year periods: Period 1, no PAM, occasional leukoreduction, and Period 2, consistent leukoreduction and extended PAM (Rh, Kell, S, Fy, Jk) for patients already alloimmunized. Patients transfused in Period 1 were excluded from Period 2.

RESULTS

A total of 293 patients were transfused in Period 1 and 183 in Period 2. Median time between first sample and last type and screen after transfusion was 2.12 years in Period 1 and 1.03 years in Period 2. Initial alloimmunization prevalence was lower in Period 2 (26.2%) versus Period 1 (37.5%) and after subsequent transfusions in Period 2 (23.8%) versus Period 1 (45.7%), although without significant difference after adjusting for number of units transfused, percentage of leukoreduced RBCs, sex, and age. Alloimmunized patients received more nonleukoreduced RBCs in Period 1 than nonalloimmunized. Patients transfused during inflammatory conditions were not significantly more likely to become alloimmunized.

CONCLUSIONS

The prevalence of initial and subsequent RBC alloimmunization in Period 2 was lower than that in Period 1; however, overall prevalence remained high. We recommend leukoreduced, hemoglobin S-negative Rh and Kell PAM RBCs for transfusion of patients with SCD. Component and recipient factors affecting alloimmunization should be studied further.

Evolving treatment paradigms in sickle cell disease

Sickle cell disease (SCD) is an inheritable hemoglobinopathy characterized by polymerization of hemoglobin S in red blood cells resulting in chronic hemolytic anemia, vaso-occlusive painful crisis, and multiorgan damage. In SCD, an increased reactive oxygen species (ROS) generation occurs both inside the red blood cells and inside the vascular lumen, which augment hemolysis and cellular adhesion. This review discusses the evolving body of literature on the role of ROS in the pathophysiology of SCD as well as some emerging therapeutic approaches to SCD with a focus on the reduction of ROS.

Incidence and predictive score for delayed hemolytic transfusion reaction in adult patients with sickle cell disease

Delayed hemolytic transfusion reaction (DHTR) is a life-threatening complication of transfusion in sickle cell disease (SCD). The frequency of DHTR is underestimated because its symptoms mimic those of vaso-occlusive crisis and antibodies (Abs) are often not detectable. No predictive factors for identifying patients likely to develop DHTR have yet been defined. We conducted a prospective single-center observational study over 30 months in adult sickle cell patients. We included 694 transfusion episodes (TEs) in 311 patients, divided into occasional TEs (OTEs: 360) and chronic transfusion program (CTEs: 334). During follow-up, 15 cases of DHTR were recorded, exclusively after OTEs. DHTR incidence was 4.2% per OTE (95% CI [2.6; 6.9]) and 6.8% per patient during the 30 months of the study (95% CI [4.2; 11.3]). We studied 11 additional DHTR cases, to construct a predictive score for DHTR. The DHTR mortality is high, 3 (11.5%) of the 26 DHTR patients died. The variables retained in the multivariate model were history of DHTR, number of units previously transfused and immunization status before transfusion. The resulting DHTR-predictive score had an area under the ROC curve of 0.850 [95% CI: 0.780-0.930], a negative-predictive value of 98.4% and a positive-predictive value of 50%. We report in our study population, for the first time, the incidence of DHTR, and, its occurrence exclusively in occasionally transfused patients. We also describe a simple score for predicting DHTR in patients undergoing occasional transfusion, to facilitate the management of blood transfusion in SCD patients.

Medical and economic implications of strategies to prevent alloimmunization in sickle cell disease

BACKGROUND

The pathogenesis of alloimmunization is not well understood, and initiatives that aim to reduce the incidence of alloimmunization are generally expensive and either ineffective or unproven. In this review, we summarize the current medical literature regarding alloimmunization in the sickle cell disease (SCD) population, with a special focus on the financial implications of different approaches to prevent alloimmunization.

STUDY DESIGN AND METHODS

A review of EMBASE and MEDLINE data from January 2006 through January 2016 was conducted to identify articles relating to complications of SCD. The search was specifically designed to capture articles that evaluated the costs of various strategies to prevent alloimmunization and its sequelae.

RESULTS

Currently, there is no proven, inexpensive way to prevent alloimmunization among individuals with SCD. Serologic matching programs are not uniformly successful in preventing alloimmunization, particularly to Rh antigens, because of the high frequency of variant Rh alleles in the SCD population. A genotypic matching program could offer some cost savings compared to a serologic matching program, but the efficacy of gene matching for the prevention of alloimmunization is largely unproven, and large-scale implementation could be expensive.

CONCLUSIONS

Future reductions in the costs associated with genotype matching could make a large-scale program economically feasible. Novel techniques to identify patients at highest risk for alloimmunization could improve the cost effectiveness of antigen matching programs. A clinical trial comparing the efficacy of serologic matching to genotype matching would be informative.

Efficacy and Safety of Manual Partial Red Cell Exchange in the Management of Severe Complications of Sickle Cell Disease in a Developing Country

Introduction

The realization of red cell exchange (RCE) in Africa faces the lack of blood, transfusion safety, and equipment. We evaluated its efficacy and safety in severe complications of sickle cell disease.

Patients and Method

Manual partial RCE was performed among sickle cell patients who had severe complications. Efficacy was evaluated by clinical evolution, blood count, and electrophoresis of hemoglobin. Safety was evaluated on adverse effects, infections, and alloimmunization.

Results

We performed 166 partial RCE among 44 patients including 41 homozygous (SS) and 2 heterozygous composites SC and 1 S/β0-thalassemia. The mean age was 27.9 years. The sex ratio was 1.58. The regression of symptoms was complete in 100% of persistent vasoocclusive crisis and acute chest syndrome, 56.7% of intermittent priapism, and 30% of stroke. It was partial in 100% of leg ulcers and null in acute priapism. The mean variations of hemoglobin and hematocrit rate after one procedure were, respectively, +1.4 g/dL and +4.4%. That of hemoglobin S after 2 consecutive RCE was −60%. Neither alloimmunization nor viral seroconversion was observed.

Conclusion

This work shows the feasibility of manual partial RCE in a low-resource setting and its efficacy and safety during complications of SCD outside of acute priapism.

Guidelines on the Use of Therapeutic Apheresis in Clinical Practice-Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Seventh Special Issue

The American Society for Apheresis (ASFA) Journal of Clinical Apheresis (JCA) Special Issue Writing Committee is charged with reviewing, updating, and categorizing indications for the evidence-based use of therapeutic apheresis in human disease. Since the 2007 JCA Special Issue (Fourth Edition), the Committee has incorporated systematic review and evidence-based approaches in the grading and categorization of apheresis indications. This Seventh Edition of the JCA Special Issue continues to maintain this methodology and rigor to make recommendations on the use of apheresis in a wide variety of diseases/conditions. The JCA Seventh Edition, like its predecessor, has consistently applied the category and grading system definitions in the fact sheets. The general layout and concept of a fact sheet that was used since the fourth edition has largely been maintained in this edition. Each fact sheet succinctly summarizes the evidence for the use of therapeutic apheresis in a specific disease entity. The Seventh Edition discusses 87 fact sheets (14 new fact sheets since the Sixth Edition) for therapeutic apheresis diseases and medical conditions, with 179 indications, which are separately graded and categorized within the listed fact sheets. Several diseases that are Category IV which have been described in detail in previous editions and do not have significant new evidence since the last publication are summarized in a separate table. The Seventh Edition of the JCA Special Issue serves as a key resource that guides the utilization of therapeutic apheresis in the treatment of human disease. J. Clin. Apheresis 31:149-162, 2016. © 2016 Wiley Periodicals, Inc.

Safety and feasibility of red cell exchange for sickle cell disease across Canada

We outline a case whereby RBCX was successfully provided over disparate geographical areas and time zones in Canada and overcame the logistical challenges of coordinating care across four different health care systems with the application of modern telecommunication technologies. We present this case as a model for other SCD providers and patients.

Effectiveness of red blood cell exchange, partial manual exchange, and simple transfusion concurrently with iron chelation therapy in reducing iron overload in chronically transfused sickle cell anemia patients

BACKGROUND

Chronic transfusion therapy (CTT) is indicated for stroke prevention in children with sickle cell anemia (SCA) and is complicated by iron overload and alloimmunization. CTT is performed by simple transfusion (ST), partial manual exchange (PME), or erythrocytapheresis (RCE). Although small case series have demonstrated RCE in combination with iron chelation therapy stabilizes and/or decreases ferritin, there are no reports comparing the effect of ST, PME, and RCE on liver iron concentration (LIC). CTT modality effect on serum ferritin and LIC were compared in SCA patients on iron chelation, with hemoglobin (Hb)S goal of 30%.

STUDY DESIGN AND METHODS

Medical records of SCA patients on CTT and deferasirox (≥25 mg/kg/day) were retrospectively reviewed. Mean HbS%, change in ferritin and LIC, and alloimmunization rate were determined for each CTT group.

RESULTS

Twenty-eight patients were included; six crossed over (one from ST to PME, one from ST to PME then to RCE, three from ST to RCE, and one from PME to RCE) to include 36 transfusion modality intervals. Median pretransfusion HbS% levels were 32.7% (ST), 36.2% (PME), and 34.7% (RCE; p = 0.732). Median ferritin changes were +15 (-17 to +45), +38 (+24 to +105), and -91 (-141 to -48) ng/mL/month (p = 0.003), and median LIC changes (available in 22 patient transfusion modality intervals) were +1.3 (-1.6 to +4.3), +2.3 (-6.5 to +8.9), and -5.7 (-10.7 to -0.5) mg/g/year (p = 0.024) in ST, PME, and RCE, respectively. There was no significant difference in alloimmunization rate between ST/PME and RCE groups.

CONCLUSION

We recommend RCE plus chelation as an effective method for reducing iron overload, while maintaining HbS at 30% to 35%.

Safety, tolerability, and outcomes of regular automated red cell exchange transfusion in the management of sickle cell disease

We report here our experience with regular automated red cell exchange transfusion for the management of chronic complications of sickle cell disease in 50 patients in our institution from June 2011 to December 2014. The mean sickle hemoglobin level was 44% and 8.5% pre- and post-transfusion, respectively. Platelets were reduced by a mean 70% during the procedure with a count of less than 50 × 10⁹ /l in 6% of cases. The alloimmunization rate was 0.065/100 units of red cells with no hemolytic reactions. Patients with no iron overload at baseline showed no evidence of iron accumulation with a mean liver iron concentration of 1.6 mg/g dry tissue and 1.9 mg/g dry tissue at baseline and 36 months, respectively. All six patients with pre-existing iron overload and on chelation therapy, showed a gradual reduction of their liver iron concentration and two patients could discontinue chelation during the follow-up period. Seventy percentage of patients who were on the programme for recurrent painful crises showed a sustained reduction in the number of emergency hospital attendances; the mean number of days in hospital for emergency treatment was 103 in the year prior to commencing ARCET and reduced to 62 (40%) after the first 12 months, 51 (50%) after 24 months, and 35 days (66%) after 36 months. J. Clin. Apheresis 31:545-550, 2016. © 2015 Wiley Periodicals, Inc.

Immunophenotypic parameters and RBC alloimmunization in children with sickle cell disease on chronic transfusion

Alloimmunization against red blood cell (RBC) antigens is a cause of morbidity and mortality in transfused patients with sickle cell disease (SCD). To investigate distinguishing characteristics of patients who develop RBC alloantibodies after transfusion (responders) versus those who do not (non-responders), a cross-sectional study of 90 children with SCD on chronic RBC transfusion therapy at a single institution was conducted in which 18 immune parameters (including T and B cell subsets) were tested via flow cytometry, and medical records were reviewed. RBC alloimmunization was present in 26/90 (29%) patients, with anti-E, K, and C among the most commonly detected alloantibodies despite prophylactic matching for these antigens at the study institution. In addition, RBC autoantibodies had been detected in 18/26 (69%) of alloimmunized versus 7/64 (11%) of non-alloimmunized patients (P < 0.0001). Alloimmunized patients were significantly older (median 13.0 years vs. 10.7 years, P = 0.010) and had more RBC unit exposures (median 148 U vs. 82 U, P = 0.020) than non-alloimmunized patients. Sex, age at initiation of chronic transfusion, splenectomy, stroke, and transfusion outside of the study institution were not significantly associated with RBC alloimmunization. Alloimmunized patients had a significantly increased percentage of CD4+ T memory cells compared to non-alloimmunized patients (57% vs. 49%, P = 0.0047), with no other significant differences in immune cell subsets or laboratory values detected between these groups. Additional research of RBC alloimmunization is needed to optimize transfusion therapy and to develop strategies to prevent alloimmunization.