Preventive extended red blood cell antigen matching: when and how?

Preventive extended red blood cell antigen matching: when and how?
Red blood cell (RBC) alloimmunization after blood transfusions results from the
genetic disparity between patient and donor. After multiple transfusions, up to
60% of patients will develop alloantibodies. In more than 80% of cases, these
antibodies are directed against the clinically relevant
C-,c-,E-,e-,K-,Fya-,Jka-, and S antigens. This high immunization rate led to
the policy to prophylactically match RBC transfusions for Rh-C,-c,-E,-e and K
antigens for high risk hematological patients and females in their
(pre)reproductive age. For all other patients, red blood cell transfusions are
only ABO-D compatible. When antibodies are detected in case of a subsequent
transfusion event, RBCs also compatible with these antibodies are selected.
This requires extensive and time consuming manual assays in a reference
laboratory, which can cause delay of treatment. Furthermore, for patients with
multiple antibodies, compatible blood may not be readily available.
A longer life expectancy is associated with an increased probability of repeat
surgery or diseases, which in turn can increase the chance of multiple
transfusion events. Except of particular populations, patients at risk for RBC
alloimmunization and the costs associated with it are unknown. The development
of micro-array and bead technology will inevitably lead to the possibility of
extensive RBC genotyping of donors. Prior to the availability of this
technology, we will identify patients for whom preventive matching is most
efficient and know the costs associated with RBC alloimmunization and
transfusion support.

To reduce the incidence of alloimmunization through preventive donor matching
for the clinically relevant red blood cell antigens.

Patients included in the study will be stratified into two strata. The stratum
is defined by transfusion history and the presence (high risk) or absence
(random risk) of antibodies. In both strata, patients are randomly assigned to
receive standard RBC or extended matched RBC transfusions. Detection of
antibody formation will take place during 3 fixed time points.

Standard ABO-D compatible versus extended (C,c,E,e,K,Fya,Jka and S) compatible
red blood cell products. Both have equal standard product-specifications

Although red cell transfusions are considered to be safe, adverse transfusion
reactions may occur. Not only are all transfusion reactions registered for the
purpose of this study, but they are also reported to the *TRIP Landelijk
Hemovigilantie Bureau* and handled according to the CBO consensus as is
routinely done in current medical practice. The study intervention could
theoretically lead to unintended transfusion delays. In case of clinical
consequences due to delays, the transfusion committee of the local hospital
will be informed.