Effectiveness of WBC reduction in neonates: what is the evidence of benefit?

BACKGROUND: The presence of WBCs in RBCs is thought to be associated with a number of significant adverse effects in recipients. In adults, WBC reduction has been shown to reduce the frequency of HLA alloimmunization, CMV and HTLV infections, and febrile nonhemolytic transfusion reactions. However, neonates are unique, given that they have an immature immune system and are frequently transfused with RBCs. Thus, the aims of this systematic review were to determine whether WBC reduction of RBCs transfused to neonates decreases the transmission of CMV, reduces the ability to develop HLA antibodies, or reduces the risk of immunomodulation. In addition, nosocomial infection, mortality, and duration of stay were identified and analyzed. STUDY DESIGN AND METHODS: All studies of WBC reduction were identified by a systematic review of the literature. Studies meeting the inclusion criteria were grouped based on study outcome. Where appropriate, studies were pooled to obtain an overall measure of effect. RESULTS: Nine eligible studies were identified from the systematic literature search, and six were deemed evaluable. Two studies evaluated WBC reduction and the development of CMV, with different results. The pooled OR was 0.19 (95% Cl, 0.01-3.41), suggesting a clinical but nonsignificant effect. Two studies evaluated WBC reduction and HLA antibody development. As with CMV, the two studies were not congruent in their results. The pooled OR was 0.17 (95% Cl, 0.01-2.43). As for immunomodulation, two small studies presented evidence of a statistically significant change in lymphocyte subsets. No studies were identified with a primary objective of evaluating the impact of WBC reduction on nosocomial infection, mortality, or duration of stay. CONCLUSION: Current evidence suggests that WBC reduction may be effective in neonates; however, further studies are needed. The lack of convincing data and the significant cost of WBC reduction mandate evaluations to determine the clinical and economic impact.