Allergic transfusion reactions to platelets are more commonly associated with prepooled than apheresis components

Transfusions of pooled or apheresis platelets are seen as equally effective in increasing platelet counts with similar rates of transfusion reactions. It has been suggested that allergic transfusion reactions (ATRs) to platelets are associated with recipient and donor factors. In this study, we assessed differences in ATR rates among individuals who received platelet components at two academic medical centres.

A total of 45 189 leukoreduced platelet products were transfused during the study period of which 31 748 were apheresis units and 13 441 were pooled units.

Transfusion reactions were reported in 0·6% (277 of 45 189) of platelet transfusions. The reaction rate was significantly higher in pooled (102 of 13 441) than in apheresis (175 of 31 748) (0·76% vs. 0·55%, respectively, P = 0·01) components. However, an analysis of reactions by categories indicated that only the ATR rate was significantly higher in pooled (55 of 13 441) products as compared with apheresis (76 of 31 748) (0·41% vs. 0·24%, respectively, P = 0·0029) platelets. Moreover, there was no difference in the rate of ABO mismatch between pooled and apheresis products.

Our data indicate that pooled platelet components are associated with higher ATR rates than apheresis platelets, suggesting that these components may not be completely equivalent from the standpoint of adverse events. Further investigation is needed to address whether differences in ATRs are related to the pooling process or the extent of donor antigen exposure.