WBC-containing allogeneic blood transfusion and mortality: a meta-analysis of randomized controlled trials

An association between allogeneic blood transfusion (ABT) and mortality was reported by one team of investigators from randomized controlled trials (RCTs) comparing recipients of non-WBC-reduced versus WBC-reduced RBCs in open-heart surgery. A meta-analysis was undertaken to examine whether this finding can be generalized across clinical settings and/or transfused RBC components.

RCTs reporting on adverse immunomodulatory effects of ABT between January 1992 and August 2002 were retrieved. Fourteen studies had recorded mortality as a primary or secondary outcome and met all other criteria for meta-analysis. Summary ORs of mortality in a treatment arm receiving WBC-containing allogeneic RBCs versus a control arm receiving autologous or WBC-reduced allogeneic RBCs were calculated across studies, for groups of studies in which the hypothesis of homogeneity was not rejected.

There was no association between ABT and mortality across 14 RCTs reporting on short-term mortality (summary OR, 1.20; 95% CI, 0.87-1.65) or across 3 RCTs reporting on long-term mortality (summary OR, 0.87; 95% CI, 0.64-1.19). In subgroup analyses, RCTs using autologous blood or conducted in abdominal or vascular surgery showed no difference in mortality, but short-term mortality differed across 3 RCTs conducted in open-heart surgery (summary OR, 2.26; 95% CI, 1.31-3.90; p < 0.05) and 7 RCTs comparing recipients of non-WBC-reduced versus WBC-reduced allogeneic RBCs filtered before storage (summary OR, 1.45; 95% CI, 1.00-2.11; p >/= 0.05).

An association between ABT and either short-term or long-term mortality was not detected across clinical settings and transfused RBC components, but subgroup analyses suggest that an association between WBC-containing ABT and short-term mortality may exist in open-heart surgery and in settings where WBC-reduced allogeneic RBCs filtered before storage are administered.