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Length of storage for transfused red blood cells not associated with patient mortality

Red blood cells stored for up to 42 days remain viable, and findings published in Annals of Internal Medicine concluded that patient survival after blood transfusion was not affected by the length of red blood cell storage.

“Red blood cells (RBCs) undergo various physiologic changes during storage, but whether the changes observed in vitro are clinically significant or are associated with mortality in the recipient is under debate,” Märit Halmin, MD, from the Karolinska Insitutet in Stockholm, and colleagues wrote.

“Despite many studies, including four randomized trials, no consensus exists,” they added.

Halmin and colleagues conducted a large population-based cohort study to investigate the relationship between mortality and length of RBC storage in patients who received transfusions in Sweden or Denmark between 2003 and 2012 (n = 854,862). The researchers followed patients from their first blood transfusion. Using three analytic approaches (discrete exposure grouping, time-dependent and instrumental variable), they evaluated relative and absolute risks for death in 30 days or 1 year in regards to length of RBC storage. Cox proportional hazard regression was performed for all analyses.

Analysis revealed that there was no association between length of RBC storage and mortality regardless of analytic approach. Among patients receiving blood stored for 30 to 42 days and those receiving blood stored for 10 to 19 days, there was a 30-day cumulative mortality difference of –0.2% (95% CI, –0.5% to 0.1%). The hazard ratio of death was 1 (95% CI, 0.96-1.05) for patients who received more than 6 units of RBCs stored for 30 days or longer.

“Overall, the results were homogenous, with sufficiently high statistical precision to exclude absolute mortality differences greater than 0.5% to 1% in comparing the most extreme exposure categories,” Halmin and colleagues concluded.

“As such, we see no reason to change the current practices for storage of RBC units.” – by Alaina Tedesco

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Disclosure: The authors report primary funding from the Swedish Research Council, Swedish Heart–Lung Foundation, Swedish Society for Medical Research, Strategic Research Program in Epidemiology at Karolinska Institutet and Danish Council for Independent Research.