Alloexposed blood donors and transfusion-related acute lung injury: a case-referent study

BACKGROUND: Donor white blood cell (WBC) antibodies are thought to increase the risk of transfusion-related acute lung injury (TRALI). WBC antibodies can be present in blood products from donors who have been alloexposed. Alloexposed donors are increasingly excluded from donating plasma, but can still donate plasma-poor products. We aimed to quantify the contribution of alloexposed donors to the occurrence of TRALI for different blood product types. STUDY DESIGN AND METHODS: We performed a case-referent study including all reported TRALI patients and all Dutch blood donors. Data on alloexposure status of donors of all TRALI cases reported between January 2004 and October 2008, in the Netherlands, were compared to information on the total donor population. RESULTS: Alloexposure status of all 223 involved donors was compared to the expected status. The overall percentage of TRALI cases that could have been prevented by the deferral of all alloexposed donors (i.e., population-attributable risk [PAR]) was 51% (95% confidence interval [CI], 14%-88%). In 19 recipients of exclusively plasma-poor products (mostly red blood cells [RBCs]), alloexposure of the donors was not associated with TRALI, while in 28 recipients of both plasma-poor and plasma-rich products (>200 mL plasma), the PAR was 94% (95% CI, 34%-100%). CONCLUSIONS: Alloexposed donors conferred an increased risk of TRALI in recipients of plasma-rich products, but not in recipients of plasma-poor products. Although WBC antibodies are an important risk factor for TRALI, among RBC recipients another risk factor must be more important.