Length of Storage of Red Blood Cells and Patient Survival After Blood Transfusion: A Binational Cohort Study.

BACKGROUND

Possible negative effects, including increased mortality, among persons who receive stored red blood cells (RBCs) have recently garnered considerable attention. Despite many studies, including 4 randomized trials, no consensus exists.

OBJECTIVE

To study the association between the length of RBC storage and mortality in a large population-based cohort of patients who received transfusions, allowing detection of small yet clinically significant effects.

DESIGN

Binational cohort study.

SETTING

All transfusion recipients in Sweden and Denmark.

PATIENTS

854 862 adult patients who received transfusions from 2003 to 2012.

MEASUREMENTS

Patients were followed from first blood transfusion. Relative and absolute risks for death in 30 days or 1 year in relation to length of RBC storage were assessed by using 3 independent analytic approaches. All analyses were conducted by using Cox proportional hazards regression.

RESULTS

Regardless of the analytic approach, no association was found between the length of RBC storage and mortality. The difference in 30-day cumulative mortality between patients receiving blood stored for 30 to 42 days and those receiving blood stored for 10 to 19 days was -0.2% (95% CI, -0.5% to 0.1%). Even among patients who received more than 6 units of RBCs stored for 30 days or longer, the hazard ratio of death was 1.00 (CI, 0.96 to 1.05) compared with those who received no such units.

LIMITATION

Observational study; risk of confounding by indication.

CONCLUSION

Consistent with previous randomized trials, this study found no association between the length of storage of transfused RBCs and patient mortality. Results were homogeneous, with differences in absolute mortality consistently less than 1% among the most extreme exposure categories. These findings suggest that the current practice of storing RBCs for up to 42 days does not need to be changed.

PRIMARY FUNDING SOURCE

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.