Sickle cell disease (SCD) is the most common monogenic disorder in sub-Saharan Africa (SSA). Blood transfusion to increase the oxygen carrying capacity of blood is vital in the management of many patients with SCD. However, red blood cell (RBC) alloimmunization is a major challenge to transfusions in these patients. Commonly in SSA, pretransfusion tests only involve ABO D grouping and compatibility without RBC antibody testing. Data on the frequency of RBC alloimmunization in patients with SCD in SSA are limited. We performed a systematic review and meta-analysis on available data on alloimmunization in transfused patients with SCD to determine the published prevalence of RBC alloimmunization in SCD patients in SSA. Six databases were systematically searched to identify relevant studies, without year or language restrictions. In all, 249 articles were identified and 15 met our selection criteria. The overall proportion of alloimmunization was 7.4 (95% confidence interval: 5.1-10.0) per 100 transfused patients. Antibodies against E, D, C, and K antigens accounted for almost half of antibody specificities, and antibodies to low- and high-frequency antigens were also common and represented almost 30% (20% to low-frequency antigens and 9% to high-frequency antigens) of specificities. Heterogeneity between studies was moderate, and meta-analysis found region of Africa as the major contributor to the heterogeneity. We also observed inconsistencies across studies in reporting of factors that may influence alloimmunization. This review provides an overview of the extent of the alloimmunization problem in SSA and provides a baseline against which to compare the effect of any interventions to reduce the alloimmunization risk.

镰状细胞病（SCD）是撒哈拉以南非洲（SSA）最常见的单基因病。输血以增加血液的氧气吸收能力在许多SCD患者的治疗中至关重要。但是，红细胞（RBC）同种免疫是这些患者输血的主要挑战。通常在SSA中，输血前测试仅涉及ABO D分组和兼容性，而无需进行RBC抗体测试。关于SSA SCD患者中RBC同种免疫频率的数据有限。我们对SCD输血患者同种免疫的可用数据进行了系统的回顾和荟萃分析，以确定SSA中已发表的SCD患者RBC同种免疫的患病率。系统搜索了六个数据库，以识别相关研究，而没有年度或语言限制。在所有，确定249篇文章，其中15篇符合我们的选择标准。每100例输血患者中，同种免疫的总比例为7.4（95％置信区间：5.1-10.0）。针对E，D，C和K抗原的抗体几乎占抗体特异性的一半，针对低频和高频抗原的抗体也很常见，占近30％（低频抗原为20％，高频抗原为9％频率抗原）的特异性。研究之间的异质性中等，荟萃分析发现非洲地区是异质性的主要贡献者。在报告可能影响同种免疫的因素的研究中，我们还观察到不一致。