Patient ABO blood type is a major predictor of a positive DAT following a transfusion reaction

Abstract

ABSTRACTBackgroundA direct antiglobulin test (DAT) checks for antibody or complement on the surface of RBCs and is often done following a transfusion reaction. While passive anti-A and anti-B antibodies are known to cause positive DATs, the extent this occurs following transfusion is unknown.Study Design and methodsDAT results, ABO type and blood product information was recorded on 1097 transfusion reactions at a large academic hospital over 8 years. The effect of patient blood type, product type and plasma compatibility of blood product transfused on DAT results were determined. Statistical significance was determined using Chi-squared testing.ResultsPlasma compatibility of the product was a strong predictor of a positive DAT with plasma compatible transfusions having a 9.4% positive rate while plasma incompatible transfusions were positive 44% of the time (P<0.0001). Patient ABO blood type was a strong predictor of a positive DAT with Type O patients having 6.6% positive rate and non-O patients having a positive rate of 20.6% (P <0.0001). These results were significant for individual blood types as well. Type A, B or AB patients had higher DAT positive rates even when plasma incompatible transfusions were excluded from the analysis (P<0.0001). Platelets were significantly more likely to be associated with a positive DAT when compared to RBC transfusions.ConclusionsThese results show plasma compatibility and ABO types are strong predictors of positive DAT results following a transfusion reaction. Anti-A and anti-B antibodies are estimated to account for about 50% of positive DATs in this study.