Prolonged red cell storage before transfusion increases extravascular hemolysis

Abstract

Background: Some countries have limited the maximum allowable storage duration for red cells to 5 weeks before transfusion. In the US, red blood cells can be stored for up to 6 weeks, but randomized trials have not assessed the effects of this final week of storage on clinical outcomes.

Methods: Sixty healthy adult volunteers were randomized to a single standard, autologous, leukoreduced, packed red cell transfusion after 1, 2, 3, 4, 5, or 6 weeks of storage (n = 10 per group). 51-Chromium posttransfusion red cell recovery studies were performed and laboratory parameters measured before and at defined times after transfusion.

Results: Extravascular hemolysis after transfusion progressively increased with increasing storage time (P < 0.001 for linear trend in the AUC of serum indirect bilirubin and iron levels). Longer storage duration was associated with decreasing posttransfusion red cell recovery (P = 0.002), decreasing elevations in hematocrit (P = 0.02), and increasing serum ferritin (P < 0.0001). After 6 weeks of refrigerated storage, transfusion was followed by increases in AUC for serum iron (P < 0.01), transferrin saturation (P < 0.001), and nontransferrin-bound iron (P < 0.001) as compared with transfusion after 1 to 5 weeks of storage.

Conclusions: After 6 weeks of refrigerated storage, transfusion of autologous red cells to healthy human volunteers increased extravascular hemolysis, saturated serum transferrin, and produced circulating nontransferrin-bound iron. These outcomes, associated with increased risks of harm, provide evidence that the maximal allowable red cell storage duration should be reduced to the minimum sustainable by the blood supply, with 35 days as an attainable goal.REGISTRATION. ClinicalTrials.gov NCT02087514.

Funding: NIH grant HL115557 and UL1 TR000040.

Conflict of interest statement

The authors have declared that no conflict of interest exists.

Figures

Figure 1. Number of subjects who were randomized, dropped out, and completed the study.

51-Cr, 51-chromium.

Figure 2. Nontransferrin-bound iron is increased predominantly after 6 weeks of red blood cell storage.

(A) Circulating nontransferrin-bound iron levels from pretransfusion to all posttransfusion time points are shown for each subject who completed the study. Nontransferrin-bound iron levels are negative in healthy subjects using the ultrafiltration assay (39). (B) The medians (I bars represent interquartile ranges) are shown for the change in nontransferrin-bound iron from pretransfusion to all time points between 0 and 20 hours after transfusion. Statistical significance for ANOVA using post-hoc Tukey’s test of the AUC among groups is shown. ***P < 0.001 compared with all other groups. n = 52 total.

Figure 3. Markers of extravascular hemolysis are increased following transfusion of red cells stored for longer duration.

(A and B) Medians (I bars represent interquartile ranges) for the changes in indirect bilirubin and serum iron, as labeled, are shown from pretransfusion to all posttransfusion time points. (C) Median transferrin saturation is also shown from pretransfusion to all posttransfusion time points. Statistical significance for ANOVA using post-hoc Tukey’s test of the AUC among the groups is shown. n = 52 total. *P < 0.05; **P < 0.01; ***P < 0.001. Asterisks without brackets represent significance compared with all other groups.

Figure 4. Markers of intravascular hemolysis are not increased following transfusion of a single, autologous red cell unit into healthy volunteers.

(A–D) Medians (I bars represent interquartile ranges) for the changes in lactate dehydrogenase, haptoglobin, plasma-free hemoglobin, and total protein are shown from pretransfusion to all posttransfusion time points, as labeled. n = 52 total.

Figure 5. Serum hepcidin is increased following transfusion of red cells stored for longer duration, but this does not appear to be mediated by circulating IL-6 levels.

(A and B) Medians (I bars represent interquartile ranges) for the changes in serum hepcidin and IL-6, as labeled, are shown from pretransfusion to all posttransfusion time points. Statistical significance for ANOVA using post-hoc Tukey’s test of the AUC among the groups is shown. *P < 0.05. n = 52 total.

Figure 6. Transfusion of red cells after longer duration of storage is associated with decreased red cell recovery, decreased change in hematocrit, and increased iron stores.

(A) The 51-chromium 20-hour posttransfusion red blood cell recovery is shown. The dotted red line denotes the FDA criterion for acceptability (i.e., at outdate, on average >75% of transfused red blood cells should still be circulating after 24 hours). n = 51 total. (B and C) The changes in hematocrit and serum ferritin, respectively, for each subject from pretransfusion to 20 hours after transfusion are shown. n = 52 total. Results of linear regression are shown with the 95% CI in dashed black lines.