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Extended red blood cell storage does not increase in-hospital mortality
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Transfusing red blood cells stored longer than 35 days did not increase risk for in-hospital death compared with fresh blood, according to a secondary analysis of the randomized controlled INFORM trial.
Although a meta-analysis of randomized controlled trials did not show a difference for in-hospital mortality between transfused fresh and stored red blood cells, uncertainty remained on whether red blood cells stored for the longest duration — 36 to 42 days — increased the risk for morbidity or mortality compared with storage of no longer than 7 days.
“If you look at red cells after blood is stored for 36 to 42 days, the cells look very abnormal — they are crenated and clumped and do not have the normal biconcave disk shape,” Nancy Heddle MSc., FCSMLS(D), director of the transfusion research program at McMaster University, told HemOnc Today. “Other biochemical and immunological markers are also abnormal. This storage lesion that occurs to red blood cells is so dramatic that it led to the hypothesis for all research to date, that stored blood had to be harmful.”
Heddle and colleagues conducted a secondary analysis of the INFORM study to investigate the effects from short- and long-term storage of red blood cells for transfusions on in-hospital morbidity or mortality.
Researchers randomly assigned patients 2:1 to receive blood stored for the longest time or the shortest time.
For the exploratory secondary analysis, Heddle and colleagues classified 24,726 patients into one of three exposure categories:
- exclusively exposed to red blood cells stored no longer than 7 days (n = 1,392);
- exposed to at least one unit of red blood cells stored 8 to 35 days (n = 18,854); or
- exposed to least one unit of red blood cells stored longer than 35 days (n = 4,480).
In-hospital mortality by storage length of transfused red blood cells served as the primary endpoint.
Median follow-up was 11 days.
After adjusting for stratification and fixed and time-dependent factors, additional storage time did not affect risk for death (HR = 0.98; 95% CI, 0.93-1.03).
When adjusted for categorical exposure variables, the risk for in-hospital death also did not differ between patients who received red blood cells stored for 8 to 35 days compared with those exposed to red blood cells stored 7 days or less among patients with blood types A or O (HR = 0. 92; 95% CI, 0.74-1.15) and all patients (HR = 0.9; 95% CI, 0.73-1.1).
Similarly, individuals exposed to red blood cells stored for more than 35 days demonstrated a comparable risk for in-hospital death as patients exposed to red blood cells stored 7 days or less in patients with blood types A or O (HR = 0.94; 95% CI, 0.73-1.2) and in all patients (HR = 0.91; 95% CI, 0.72-1.14).
“This study ... alleviates any concern for harm that could occur when blood stored for 36 to 42 days is transfused and suggests that inventory management practices do not need to be changed,” Heddle said.
Instead, a trend occurred among patients who received fresh blood.
“Intriguing to me is the fact that so many of the randomized controlled trials have shown a trend of higher mortality when fresh blood is transfused,” she added. “Perhaps our future focus should be on understanding whether fresh blood is harmful and, if so, what the mechanism could be rather than investing more time and money on the storage lesion.”
In addition to patient care implications, this study may affect regulatory practices, Eric A Gehrie, MD, and Aaron A.R. Tobian, MD, PhD, from the department of pathology at Johns Hopkins University School of Medicine, wrote in an accompanying editorial.
“The transfusion community has been anxiously asking questions about best practice, and these data presented by Cook and colleagues seem to have provided a definitive answer,” they wrote. Gehrie and Tobian also acknowledged the findings are consistent with AABB guidelines, which state patients should receive red blood cell units selected at any point within their licensed dating period rather than limiting patients to transfusion of only fresh red blood cell units.
“After so many studies, it seems that the transfusion medicine community can finally be reassured that patient outcomes are not meaningfully altered by transfusing red blood cells that are approaching their 42-day outdate,” they added. – by Kristie L. Kahl
Disclosures: The authors, Gehrie and Tobian report no relevant financial disclosures.
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