3). The study site (clustering), leukodepletion status, number of RBC transfusions and pre-ICU transfusions (RBCs, platelets, fresh frozen plasma yes/no) did not show an independent association inhibitor expert with hospital mortality.Table 3Univariate and multivariate logistic regression analysis in patients with APACHE III scoresThe area under the curve for the multivariate model was 0.86, and a Hosmer-Lemeshow P = 0.93 suggested the model adequately fitted the data. A graphic trend for the adjusted hospital death according to the maximum age of RBCs is presented in Figure Figure11 for illustration. There were no significant interactions between the maximum age of blood and all other variables in the multivariate model. In addition, the predicted risk of death against the maximum age of RBCs with LOWESS is presented in Figure Figure22.

Figure 1Hospital mortality according to maximum age of red blood cells. Hospital mortality (%, 95% confidence interval) according to the maximum age of red blood cells (RBCs) (days). Patients with the maximum age of RBCs exceeding each cut-off point are excluded. …Figure 2Predicted risk of death against maximum age of red blood cells. A locally weighted nonparametric smoother (LOWESS) for the predicted probability of death and the maximum age of red blood cells.DiscussionWe conducted a prospective observational study in 47 ICUs in Australia and New Zealand to assess the association between age of RBCs and outcome. In critically ill patients receiving RBCs, we found an association between exposure to older red cells and increased hospital mortality rate.

This association remained after adjustment for potential confounding factors.In this study, the mean age of all RBCs was 16.2 days and the oldest RBC unit given to each patient was 19.6 days on average. This compares with 21.2 days in the United States [1] and 16.2 days in Europe [7]. In 2007, the mean calculated age of transfused RBCs in the United States was 19.5 days, although just 7.8% of the hospitals reported such data [27]. Our results, therefore, are in agreement with the mean age of RBCs in previous studies and in other countries.The mean pretransfusion hemoglobin values in previous studies – namely 8.6 g/dl in the United States [1] and 8.4 g/dl in Europe [7] – are in line with our mean pretransfusion hemoglobin concentration.

In a previous study in Australia and New Zealand conducted in 2001 by French and colleagues the median pretransfusion hemoglobin level was 8.2 g/dl Cilengitide [6], compared with 7.7 g/dl in the present study. In keeping with published evidence [9], therefore, Australian and New Zealand transfusion practice appears to have moved toward a more restrictive approach during recent years.There is no suitably powered randomized controlled trial of the effect of age of RBCs on mortality [28].