Transfusion of leukoreduced red blood cells may decrease postoperative infections: two meta-analyses of randomized controlled trials

To evaluate the efficacy and effectiveness of red blood cell leukoreduction in reducing postoperative infection, mortality and cancer recurrence, two meta-analyses of randomized controlled trials (RCTs) were conducted. A systematic search of the scientific literature was conducted. The pooled relative risk ratio (RR) of developing an adverse postoperative outcome with either leukoreduced or non-leukoreduced blood was calculated using a random effects model. To better estimate the efficacy of leukoreduction, a second analysis of transfused patients only was conducted. Ten RCTs met inclusion criteria and eight provided separate data for patients randomized and transfused. The mean percentage of patients randomized but not transfused was 34%. For postoperative infection, the overall pooled RR was 0.76 [(95% confidence interval (CI): 0.54-1.08] for the "all patients randomized" analysis. For the "only patients transfused" analysis, the pooled RR became clinically and statistically significant (RR = 0.60 (95% CI: 0.38-0.93). For mortality, the pooled RR for the "all patients randomized" analysis was 0.71 (95% CI: 0.45-1.13) and 0.61 (95% CI: 0.36-1.04) for the "only patients transfused" analysis. When analyzing either all patients randomized or all patients transfused, there was no statistically significant difference in cancer recurrence rates (one study only). We demonstrated that patients who were transfused leukoreduced red blood cells might benefit from a decrease in postoperative infections. A decrease in mortality may have been realized if more patients had been enrolled in the various randomized trials. Including all patients randomized, regardless of whether or not they were actually transfused diluted the observed clinical benefit of leukoreduction.