Sensitivity of red blood cell antibody screening test systems for anti-D: A multicentre study using external quality assessment programmes

Background Red blood cell (RBC) antibodies can cause serious and even fatal haemolytic transfusion reactions or haemolytic disease of the foetus and newborn. Therefore, the application of reliable testing procedures for their detection is of utmost importance. However, only little is known about the sensitivity of common RBC antibody screening tests (AST). Methods Detection rates of quantified but undisclosed anti-D antibodies in low concentrations, traceable to an International Standard, were investigated in four serum samples. In a concerted effort by ten external quality assessment (EQA) providers, these samples were tested by 2500 participating laboratories using RBC ASTs based on four test principles and test cells and devices from more than 24 and five manufacturers, respectively. Resulzs Detection rates decreased with decreasing anti-D antibody concentrations. The vast majority of test systems detected samples with 0.1 IU/mL anti-D antibodies, some were still reliable at 0.01 IU/mL, and a few appeared to easily detect concentrations of 0.005 IU/mL. The sensitivity of ASTs depended on the test principle they applied. Erythrocyte magnetized technique (EMT) and solid-phase RBC adhesion technique (SPRCA) consistently demonstrated above-average detection rates, and automated result reading was superior to manual reading. Test tube technology (TTT) performed below average. Column agglutination technology (CAT) represented the average, and, surprisingly, no differences in detection rates were found between automated and manual reading of the reaction results. Interpretation The results indicate significant differences between RBC ASTs in routine use. The clinical relevance of these differences has yet to be assessed. Funding None.