Irradiation and prolonged storage of red cells are associated with increased adverse events

Background: Red blood cell (RBC) transfusion is associated with the most transfusion-related adverse events (AE). Recent clinical studies showed no significant difference in transfusion-associated mortality between fresh and older RBCs. However, the impact of storage duration as well as irradiation on nonfatal yet much more common complications has not been fully investigated. Materials/methods: In this retrospective study of RBC transfusion-associated AEs, a total of 188,562 units of leucocyte-reduced RBCs were transfused in approximately 5·5 years. After excluding washed, deglycerolized, autologous or directed RBCs and RBCs transfused during a massive transfusion protocol, 149,052 units were analysed. Attributes of RBCs including storage time, collection method, CMV serological status and gamma irradiation, as well as the recipient's gender, were analysed. A total of 358 RBC transfusion AEs were categorized into allergic and non-allergic reactions and analysed. Results: Univariate and multivariate logistic analyses showed that irradiated RBCs were associated with a significantly increased frequency of non-allergic reactions (OR (95% CI): 1·89 (1·52, 2·35); P < 0·001). There was a significant association between the frequency of non-allergic reactions and the storage time of irradiated RBCs (OR (95% CI): 1·024 (1·001, 1·048); P = 0·042). In contrast, there was no association between the frequency of allergic reactions and the storage time of irradiated RBCs or between the age of non-irradiated RBCs and the frequency of non-allergic reactions. Conclusions: Prolonged storage of irradiated RBCs was associated with a significant increase in non-allergic transfusion reactions. Overall, the irradiated RBCs appeared to cause more non-allergic reactions compared with non-irradiated RBCs.