Why do people still make anti-D over 50 years after the introduction of Rho(D) immune globulin? A Biomedical Excellence for Safer Transfusion (BEST) Collaborative study

Abstract

Background: Rho(D) immune globulin (RhIg) is used to reduce RhD alloimmunization in pregnancy. This study describes potential causes for RhD alloimmunization after the development and implementation of RhIg. Study Design and Methods: This retrospective descriptive study investigated RhD-negative patients born in 1965–2005 with anti-D newly identified during 2018–2022. Transfusion, pregnancy, intravenous drug abuse, and transplantation were considered potential alloimmunization sources. Results: There were 1200 study patients (852 females; 348 males) at 30 institutions in 5 countries (USA, Canada, UK, New Zealand, Brazil). Most patients had a single potential source of alloimmunization identified (857/1200, 71%), most commonly pregnancy among females (537/852, 63%) and transfusion among males (180/348, 52%). When multiple potential sources were included, males were more likely than females to have a history of transfusion (235/348 [68%] vs. 149/852 [17%], p