{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,18]],"date-time":"2026-05-18T13:18:20Z","timestamp":1779110300374,"version":"3.51.4"},"reference-count":41,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2026,5,15]],"date-time":"2026-05-15T00:00:00Z","timestamp":1778803200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Deanship of Scientific Research, Vice Presidency for Graduate Studies and Scientific Research at King Faisal University","award":["KFU253929"],"award-info":[{"award-number":["KFU253929"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JCM"],"abstract":"<jats:p>Background\/Objectives: Blood transfusion is a crucial component in the treatment of individuals with sickle cell disease [SCD]; nonetheless, multiple transfusions can lead to considerable complications, notably alloimmunization. However, the prevalence of alloimmunization and its predictors remain incompletely explained. This review aimed to determine its global prevalence and identify associated risk factors. Method: Our protocol was registered in PROSPERO [ID: CRD420251167042] in accordance with the PRISMA 2020 criteria. A thorough literature search was conducted across PubMed, Embase, Web of Science, Scopus, and the Cochrane Library to identify studies reporting the prevalence of alloimmunization in adults with confirmed sickle cell disease who have received blood transfusions. This search included all publications up to 16 April 2026. Two reviewers independently screened and extracted data, and the Newcastle\u2013Ottawa Scale was used to evaluate the study\u2019s quality. After the Freeman\u2013Tukey transformation, a random-effects model was used to estimate the pooled prevalence. We examined disparities among groups and geographies, study designs, and matching procedures to determine their differences. We additionally employed meta-regression to identify potential predictors. Results: Nine studies [n = 1711; 1978\u20132026] met the inclusion criteria. The overall rate of alloimmunization was 28.9% [95% CI 22.4\u201335.4; I2 = 88.5%]. The most prevalent antibodies were those of the Rh and Kell systems, with anti-E antibodies being the most frequent, followed by anti-C and anti-K antibodies. A higher number of transfusions and the HbS\u03b20 genotype were both persistent risk factors, while older age at first transfusion appeared protective. Extended antigen matching dramatically reduced prevalence, though approximately 9% of individuals remained affected. Conclusions: Alloimmunization continues to challenge transfusion management in adults with SCD. Broader implementation of extended antigen matching and genotype-informed transfusion strategies may help mitigate this risk.<\/jats:p>","DOI":"10.3390\/jcm15103828","type":"journal-article","created":{"date-parts":[[2026,5,18]],"date-time":"2026-05-18T12:36:40Z","timestamp":1779107800000},"page":"3828","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Global Prevalence of Alloimmunization in Adults with Sickle Cell Disease Receiving Red Blood Cell Transfusions: A Systematic Review and Meta-Analysis"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3975-5550","authenticated-orcid":false,"given":"Mortadah","family":"Alsalman","sequence":"first","affiliation":[{"name":"Department of Medicine, College of Medicine, King Faisal University, Al Ahsa 31982, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0006-0327-1764","authenticated-orcid":false,"given":"Jawad S.","family":"Alnajjar","sequence":"additional","affiliation":[{"name":"College of Medicine, King Faisal University, Al Ahsa 31982, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-4502-8609","authenticated-orcid":false,"given":"Sarra Riyadh","family":"Alhassan","sequence":"additional","affiliation":[{"name":"College of Medicine, King Faisal University, Al Ahsa 31982, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hussain A.","family":"Almarzoug","sequence":"additional","affiliation":[{"name":"College of Medicine, King Faisal University, Al Ahsa 31982, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Qusai A.","family":"Alobaid","sequence":"additional","affiliation":[{"name":"College of Medicine, King Faisal University, Al Ahsa 31982, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Reham Riyadh","family":"Alhassan","sequence":"additional","affiliation":[{"name":"College of Medicine, King Faisal University, Al Ahsa 31982, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Maryam Mohammed","family":"Alshams","sequence":"additional","affiliation":[{"name":"College of Medicine, King Faisal University, Al Ahsa 31982, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bdoor Abdulaziz","family":"Almoqren","sequence":"additional","affiliation":[{"name":"College of Medicine, King Faisal University, Al Ahsa 31982, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nabeel Baqer","family":"Al Besher","sequence":"additional","affiliation":[{"name":"Department of Laboratory and Blood Bank, Prince Saud bin Jalawi Hospital, Al Ahsa 36377, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6035-1230","authenticated-orcid":false,"given":"Abdullah","family":"Almaqhawi","sequence":"additional","affiliation":[{"name":"Department of Family and Community Medicine, College of Medicine, King Faisal University, Al Ahsa 31982, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,5,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"e585","DOI":"10.1016\/S2352-3026(23)00118-7","article-title":"Global, regional, and national prevalence and mortality burden of sickle cell disease, 2000\u20132021: A systematic analysis from the Global Burden of Disease Study 2021","volume":"10","author":"Thomson","year":"2023","journal-title":"Lancet Haematol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"248","DOI":"10.15585\/mmwr.mm7312a1","article-title":"Birth Prevalence of Sickle Cell Disease and County-Level Social Vulnerability\u2014Sickle Cell Data Collection Program, 11 States, 2016\u20132020","volume":"73","author":"Kayle","year":"2024","journal-title":"MMWR. 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