Incidence of anti‐D alloimmunization in D‐negative individuals receiving D‐positive red blood cell transfusion: A systematic review and meta‐analysis

Abstract

Background and Objectives The transfusion of D‐negative red blood cells (RBCs) to D‐negative patients has been widely adopted to prevent anti‐D alloimmunization, especially in women of childbearing age. Still, transfusion of D‐positive RBCs to D‐negative recipients is occasionally inevitable in practice, and the resulting incidence of anti‐D in different D‐negative groups of patients has not been well summarized. Materials and Methods We searched the relevant literature using PubMed, Cochrane Library, and Embase databases from inception date to 30 September 2021. We looked for studies of anti‐D occurring in D‐negative recipients who received D‐positive RBC transfusions. The anti‐D incidence was summarized with 95% confidence intervals (CIs). Data with similar characteristics were combined using a random‐effects model. Results About 42 studies (2226 cases), which found anti‐D, the exact volume of D‐positive RBC transfused, and the follow‐up time for anti‐D detection, met the inclusion criteria. The pooled anti‐D incidence was 64% (95% CI, range 55%–74%) in volunteers receiving small volumes of D‐positive RBCs, 84% (95% CI, 74%–94%) in those receiving whole units, 26% (95% CI, 19%–32%) in mixed patients, 12% (95% CI, 8%–16%) in oncology patients, 27% (95% CI, 13%–40%) in trauma patients, 4% (95% CI, 0%–8%) in immune‐compromised transplant patients, and 6% (95% CI, 1%–39%) in those with AIDS. Conclusion Compared with the high frequency of anti‐D in healthy D‐negative volunteers given D‐positive RBCs, we found a lower rate of anti‐D immunization in various D‐negative patients and almost none in transplant and AIDS patients.

Patients with Asian-type DEL can safely be transfused using RhD-positive blood

“…The upper limit of the 95% CI for alloanti-D incidence (8.40%) in the trial group was far lower than the lower limit of the 95% CI (19.0%) in the true D-control group, as previously estimated in our meta-analysis. 32 In a large nationwide retrospective study, we found no anti-D immunization in any Asian-type DEL pregnant women (n = 1,032), despite their high probability of carrying D+ fetuses (>95%) due to the low prevalence of D heterozygotes (7%) in fathers. 29,36 In line with this, no Asian-type DEL but only true D-individuals were identified in another group of pregnant women who had developed alloanti-D (0/127), which is in agreement with two previous independent studies (0/165).…”

“…Primary alloanti-D immunization in D-recipients commonly occurs between 2 and 3 months after D+ RBC transfusion, and secondary alloanti-D immunization generally occurs within 1 month. 32 Once alloanti-D is produced, disappearance is unlikely. 40 Hence, we chose to follow the patients for more than 3 months to avoid false negative results if the anti-D immunization was delayed.…”

“…In a recent meta-analysis, the alloanti-D rate from true D-patients with similar indications receiving D+ RBC transfusion was estimated to be 28.2% (203/720, 95% confidence interval (CI), 19.0%-32.0%). 32 The primary objective of this trial was to determine whether the primary endpoint was lower than the target value of 19.0%, the lower limit of the 95% CI of the alloanti-D occurrence rate from the meta-analysis. The trial was ended when 42 Asian-type DEL patients had longer alloanti-D follow-up (>1 month), fulfilling the requirement for analysis (≥ 37, assuming an alloanti-D rate of 5%, 90% power, 2-sided at an alpha significance level of 0.05).…”

Major haemorrhage: putting evidence into practice

“…The guideline recommends using Rh‐D‐negative blood for boys aged <18 years. The D‐immunisation rate is 27% in trauma patients, 21 and it is unclear if this is a cost‐effective strategy given that children have lower alloimmunisation rates 22 …”

“…The D-immunisation rate is 27% in trauma patients, 21 and it is unclear if this is a cost-effective strategy given that children have lower alloimmunisation rates. 22 What ongoing trials are likely to inform our haemorrhage response?…”