Red blood cell alloimmunizations in beta-thalassemia patients in Casablanca/Morocco: Prevalence and risk factors

Prevalence of Alloimmunization Events in Thalassemia Patients With Repeated Transfusions in the Rhesus Blood Group System: A Systematic Review and Meta Analysis

Background

Alloimmunization presents a significant challenge for patients with β-thalassemia major who depend on regular transfusion therapy. This systematic review and meta-analysis aimed to evaluate the frequency of alloimmunization within the Rhesus blood group system and identify the most prevalent alloantibodies.

Methods

A comprehensive search across multiple databases was conducted to locate epidemiological studies reporting alloimmunization in thalassemia patients undergoing repeated transfusions, specifically focusing on Rhesus antibodies. Statistical analyses were performed using R software, and heterogeneity was assessed using I2 statistics.

Results

This review included 20 studies with a total of 4,650 patients. The overall prevalence of alloimmunization was 5.4% (95% confidence interval (CI): 3.1-9.3%) across all ages, with a prevalence of 9.1% (95% CI: 5.3-15.2%) in children and 25% (95% CI: 12.7-41.2%) in adults. The pooled overall prevalence was 6.6% (95% CI: 4.2-10.2%). Among the 488 alloimmunized patients, 310 developed Rhesus-specific antibodies, with anti-E (34.58%) and anti-D (13.69%) being the most frequent.

Conclusions

This study underscores the substantial prevalence of Rhesus antibodies among alloimmunized thalassemia patients. Implementing extended phenotype matching for transfusions could significantly reduce the risk of alloantibody formation in this population. Future analyses should explore factors influencing alloimmunization rates, such as ethnic diversity, matching protocols, and age-related variations, to inform clinical practice better.

Erythrocyte Alloimmunization and Autoimmunization in the Pediatric Population: A Multicenter, Cross-Sectional Study in Central China

Background

Erythrocyte alloantibodies and autoantibodies complicate transfusion. However, the prevalence of erythrocyte alloimmunization and autoimmunization has not been estimated in the Chinese pediatric population. Therefore, we investigated the prevalence of erythrocyte alloimmunization and autoimmunization in the Chinese pediatric population with the aim of developing a reasonable transfusion management policy in children from China.

Methods

This study included 30,603 pediatric inpatients who were admitted to three tertiary hospitals in central China from May 2020 to October 2022. Antibody screening was carried out with a three-cell panel by column agglutination technology, and samples with positive screening were analyzed for antibody specificity with a 16-cell identification panel. Clinical details of the patients were collected to identify associations with antibody formation.

Results

The alloimmunization rate was 0.55% (169/30,603), and the autoimmunization rate was 0.14% (43/30,603). Alloantibodies comprised 80.09% of the antibodies. The most frequent alloantibodies were anti-M (58.77%), anti-E (9.48%), and anti-P1 (4.27%). Autoantibodies comprised 19.91% of antibodies. Age (p = 0.000), sex (p = 0.016), geographical area (p = 0.000), ABO blood group (p = 0.008), and diagnosis (p = 0.000) were independent risk factors for antibody formation. The risk of antibody formation at the ages of 0-28 days and 1-3 months was zero (odds ratio = 0.000). The antibody distribution was significantly different by age (p = 0.000) and diagnosis (p = 0.000).

Conclusion

Repeat pre-transfusion testing for infants less than 4 months of age can be omitted for no risk of antibody formation. MNS system antibodies, especially anti-M, are prominent in younger children, and this decreases with age. Provision of extended phenotype-matched transfusion for Rh system antigens, especially antigen E, is necessary in children to control erythrocyte alloimmunization. The presence of antibodies with high evanescence rates in the pediatric population suggests the pressing need for nationwide shared transfusion records to avoid hemolytic transfusion reactions in children.

Risk Stratification for Autoimmune Hemolytic Anemia in Children With Pediatric Transfusion-Dependent Thalassemia

Objective This study aimed to identify the risk factors for autoimmune hemolytic anemia (AIHA) in children with transfusion-dependent thalassemia (TDT). Methodology This cross-sectional study was conducted at the Department of Child Health, Khyber Teaching Hospital, Peshawar, Pakistan, from March 25, 2024, to September 25, 2024. A total of 300 patients under 18 years of age, diagnosed with TDT, were included in the study. Relevant demographic, clinical, and laboratory investigations were conducted for each patient, with AIHA diagnosed based on the Coombs test. Risk factors, including demographic data, disease characteristics, transfusion history, clinical factors, and laboratory parameters, were recorded and analyzed. The significance of these risk factors was assessed by using the chi-square test for categorical variables and the independent t-test for continuous variables, comparing Coombs test-compatible and incompatible patients. A p-value of less than 0.05 was considered statistically significant. Results The mean±SD age of participants in this study was 6.82±4.2 years with an age range of one to 16 years. The male gender was 56.33%. The results of the Coombs test showed that 48.66% of these children had developed AIHA. The comparison between incompatible and compatible patients at Coombs test showed that age of patients (5.87±3.93 vs. 7.68±4.28 years, p = 0.00), age at the time of diagnosis (2.21±0.99 vs. 4.64±3.03 years, p = 0.00), age at the time of first infusion (3.05±1.28 vs. 5.49±3.2 years, p = 0.00), transfusion interval < 3 weeks (48.6% vs. 37%, p = 0.04) and duration of transfusion (2.87±3.2 vs. 2.21±1.93 years, p = 0.03) were the significant risk factors in the development of AIHA. Conclusion The patient's age, age at diagnosis, age at the time of first transfusion, the transfusion interval, and the duration of blood transfusion are the significant risk factors influencing the development of AIHA.

Human leukocyte antigen immunization in transfusion-dependent Moroccan patients with beta-thalassemia major: prevalence and risk factors

INTRODUCTION

Beta-thalassemia major patients need a regular blood transfusion to have an initial normal growth. However, these patients have an increased risk of developing alloantibodies. Our main goal was to study HLA alloimmunization in Moroccan Beta-thalassemia patients by confronting it with transfusion and demographic criteria, exploring the involvement of HLA typing profile in the development of HLA antibodies and in turn determining risk factors for their development.

METHODS

The study consisted of 53 Moroccan pediatric patients with Beta-thalassemia major. Screening for HLA alloantibodies was performed using Luminex technology Whereas HLA genotyping was done with sequence-specific primers (PCR-SSP).

RESULTS

In this study, 50.9% of patients have been identified as positive for HLA antibodies, with 59.3% having both HLA Class I and Class II antibodies. A significant increase frequency of DRB1*11 allele was revealed in non-immunized patients (34.6% vs. 0%, p = 0.001). Our results also revealed that the majority of our HLA immunized patients were women (72.4% vs. 27.6%, p = 0.001), and transfused with more than 300 units of RBC units (66.7% vs. 33.3%, p = 0.02). There were statistically significant differences when comparing these frequencies.

CONCLUSIONS

This paper revealed that the transfusion dependent Beta-thalassemia major patients are exposed to risk of developing HLA antibodies following transfusions with leukoreduced RBC units. The HLA DRB1*11 was a protective factor against HLA alloimmunization in our beta-thalassemia major patients.

[Health status and quality of life in β-thalassemia adults in Marseille, France]

INTRODUCTION

The life expectancy of β-thalassemia patients has increased over the last 20 years. In this study, we evaluated the current health status and quality of life of these patients managed in a reference center in Marseille.

METHODS

This is a single-center, descriptive study conducted between June and August 2019 in patients over 18 years of age with β-thalassemia major or intermedia. Clinical and paraclinical data were collected retrospectively and the SF-36 health survey questionnaire was proposed to each patient.

RESULTS

43 of 64 selected patients were included and divided into 2 groups: 35 patients with transfusion-dependent β-thalassemia and 8 patients with non-transfusion-dependent β-thalassemia. Liver iron overload is the most frequent complication, present in 80% of transfusion-dependent and 62.5% of non-transfusion-dependent patients. Cardiac iron overload is present only in the transfusion dependent β-thalassemia group (20%). Hypogonadotropic hypogonadism remains the most common endocrine disorder (41.9%) followed by osteoporosis (37.2%). Among the 31 patients who completed the SF-36 questionnaire, physical and mental quality of life scores were lowered in transfusion dependent (respectively 42.7 and 46.8) as in non-transfusion-dependent patients (respectively 43.8 and 28.9).

CONCLUSION

Despite an improvement in medical care, our patients with β-thalassemia show an alteration in their quality of life that will need to be characterized in the entire French cohort.

Red Blood Cell Alloimmunizations in Thalassaemia Patients With Regular Transfusion in China: a Systematic Review and Meta-Analysis

OBJECTIVE

The development of red blood cell alloimmunization intensifies transfusion complication in thalassaemia patients. The purpose of this paper is to evaluate the existing evidence on the prevalence of erythrocyte alloimmunization in China by meta-analysis. We systematically searched cross-sectional studies regarding the alloimmunization of thalassaemia patients with regular blood transfusion in China from year 2000 to May 2021 in the Cochrane library, PubMed, EMBASE, Web of Science, and Chinese databases including CNKI, Wanfang Data, Vip and CBM. Data extraction and quality evaluation of the included studies were performed. Meta-analysis was performed using the DerSimonian and Laird random-effects models with inverse variance weighting. The presence of publication bias was tested by Egger's test, and the methodological quality of each included article was evaluated by the criteria specific to prevalence studies.

RESULTS

A total of 1874 patients and 263 alloantibodies from 11 studies were identified and included in the meta-analysis. The proportion of alloantibodies against antigens belonging to the Rh, MNSs and Kidd systems were as high as 70.3%, 17.9%, and 6.5%, respectively. Meta-analysis showed that the overall prevalence of alloimmunization among transfusion-dependent thalassaemia patients in China is 11.4% (95%CI: 7.2%∼16.3%).

CONCLUSIONS

The characteristics of red blood cell alloimmunization among thalassaemia patients with regular transfusion in China differ greatly from those in other countries. Therefore, transfusion strategies shall be actively adapted in line with thalassaemia patients in China to minimize the risk of alloimmunization.

Prevalence of Red Blood Cell Alloimmunization among Transfused Chronic Kidney Disease Patients in Hospital Universiti Sains Malaysia

Objectives

Red blood cell (RBC) immunization is a common complication in blood transfusion recipients. Patients with chronic kidney disease (CKD) eventually develop anemia, which is multifactorial, and requires regular blood transfusions, which exposes patients to the development of RBC antibodies. We sought to determine the prevalence and specificity patterns of RBC immunization and its risk factors among transfused CKD patients.

Methods

We conducted a cross-sectional study over one year from January to December 2018 in the Transfusion Medicine Unit, Hospital Universiti Sains Malaysia. A total of 249 samples were recruited from CKD patients who received a blood transfusion (at least one-pint), which only match for ABO and Rh(D) antigen. The serum was screened for the presence of the RBC antibody using the gel agglutination technique (Diamed gel cards). Samples with positive antibody screening were subjected to antibody identification.

Results

Of the 249 transfused CKD patients, 31 (12.4%) developed RBC immunization. Thirty (12%) were alloimmunized, and one (0.4%) was autoimmunized. Anti-Mia was the most common antibody (n = 14, 46.7%) among alloantibodies, followed by anti-E (n = 7, 23.3%). There was a significant association between pregnancy history with the development of antibodies whereas, no significant association was found between sociodemographic background, stage of CKD, hemodialysis status, underlying medical illness, and number of packed cell transfusions with the development of RBC antibodies.

Conclusions

One-eighth of our patient cohort had RBC alloimmunization, and the risk was increased in patients with a history of pregnancy. We propose Rhesus RBC phenotyping and to supply blood match Rhesus antigen in CKD patients, especially patients of reproductive age.

Distribution of Red Blood Cell Alloantibodies Among Transfusion-Dependent β-Thalassemia Patients in Different Population of Iran: Effect of Ethnicity

The best approach for prevention of alloimmunization in β-thalassemia (β-thal) patients is perfect matching of all red blood cell (RBC) antigens associated with clinically significant antibodies, but this is expensive and may limit the blood supply. Knowing the most common alloantibodies in transfusion-dependent β-thal patients make it possible to establish more cost-effective matching strategies for high-risk antigens. With this in mind, we intended to determine the most common alloantibodies in different parts of Iran. A total of 480 alloimmunized β-thal major (β-TM) patients who were referred to the Tehran Adult Thalassemia Clinic in Tehran, Iran from all provinces between 2015 and 2017, were included in this study. Antibody screening was performed on the fresh serum of all patients. Subsequently, the specification of antibodies was identified using a panel of recognized blood group antigens. Anti-K was the most common alloantibody detected in β-TM patients in all regions of Iran. The prevalence of this antibody reached to 37.7% in the western area, but in southeastern region, anti-E was predominant. Interestingly, the rare alloantibody anti-Kp^a was detected with a high prevalence in the western region. The antibodies against E and D antigens were also encountered with high prevalence in most regions of the country. The present study demonstrated the distribution of alloantibodies in alloimmunized transfusion-dependent β-thal patients from diverse ethnic and racial backgrounds of the Iranian population. The results of this study can be used as a basis to establish cost-effective RBC phenotyping and matching strategies for high-risk antigens in donors and chronic transfusion recipients in different regions of Iran.