Anti‐D immunization after D positive platelet transfusions in D negative recipients: A systematic review and meta‐analysis.

Background: Anti‐D can be formed after D‐incompatible platelet transfusions due to contaminating D+ red blood cells. These antibodies are of particular importance in women of childbearing potential, because anti‐D is most often involved in severe cases of hemolytic disease of the fetus and newborn. This systematic review determined the frequency of anti‐D after D+ platelet transfusions and risk factors for D alloimmunization. Study Design and Methods: Relevant literature was searched using PubMed, Embase and Web of Science until December 2022. Overall anti‐D frequency and risk factors were estimated using a random effects meta‐analysis. Results: In 22 studies, a total of 3028 D‐ patients received a mean of six D+ platelet transfusions. After a mean follow‐up of seven months 106 of 2808 eligible patients formed anti‐D. The pooled anti‐D frequency was 3.3% (95% CI 2.0–5.0%; I2 71%). After including only patients with an undoubtable follow‐up of at least 4 weeks, 29 of 1497 patients formed anti‐D with a pooled primary anti‐D rate of 1.9% (95% CI 0.9–3.2%, I2 44%). Women and patients receiving whole blood derived platelets had two and five times higher anti‐D rates compared with men and patients receiving apheresis derived platelets, respectively. Discussion: Anti‐D immunization is low after D incompatible platelet transfusions and dependent on recipients' sex and platelet source. We propose anti‐D prophylaxis in girls and women, capable of becoming pregnant in the future, that received D+ platelets, regardless of platelet source, to reduce the risk of anti‐D induced hemolytic disease of the fetus and newborn. [ABSTRACT FROM AUTHOR]