Effects of change in transfusion practice, population mix and fertility on red blood cell alloantibody prevalence

Factors affecting red blood cell (RBC) alloimmunization have changed in New Zealand (NZ). We aimed to investigate whether alloimmunization prevalence had changed as a result.

We calculated the prevalence (%) of patients with RBC alloantibodies among those who had antibody screening/identification done in Canterbury, NZ, during three periods: 2006-2010 (P1), 2012-2016 (P2) and 2018-2022 (P3).

During P1, P2 and P3, respectively, females and males numbered 58,817, 30,082; 48,775, 28,383 and 56,200, 31,443. Combining the periods, the overall alloantibody prevalence in females and males was 2.4 versus 0.9, p < 0.0001, and in those ≥60 and ≤40 years, it was 1.9 versus 1.5, p < 0.0001. Prevalence declined, especially after P2. Prevalence of the five most common alloantibodies during P1, P2 and P3, respectively, was as follows: anti-E, 0.39, 0.48, 0.37; anti-D, 0.38, 0.34, 0.27; anti-K, 0.34, 0.32, 0.22; anti-Fya, 0.18, 0.19, 0.14; anti-C, 0.17, 0.16, 0.12; all alloantibodies, 2.0, 2.1, 1.5. p-values by the chi-squared test comparing prevalence (P1 vs. P2, P1 vs. P3, P2 vs. P3, respectively) were anti-E, 0.005, 0.5, 0.0006; anti-D, 0.2, <0.0001, 0.001; anti-K, 0.5, <0.0001, 0.0001; anti-Fya, 0.6, 0.04, 0.01; anti-C, 0.6, 0.006, 0.03; all alloantibodies, 0.1, <0.0001, <0.0001.

RBC alloantibody prevalence has declined. The chief reasons for this appear to be changes in transfusion management, NZ population mix and fertility. The decline is beneficial.