This retrospective study was done to assess the impact of RBC storage duration on clinical outcomes, and to specifically examine patients receiving RBCs in the last two weeks of the 6-week shelf life. Just over 16,000 patients were divided into three groups: 1) those receiving exclusively fresh RBCs (≤21 days storage), exclusively RBCs stored ≥ 28 days, and exclusively RBCs stored ≥35 days. The ≤21 day storage group served as a fresher blood control group, to which the other groups were compared.
After risk adjustment for potential confounding variables (dose of blood, casemix index, and patient age), RBCs stored ≥28 days were not associated with increased morbidity or mortality, even when the sicker patient (requiring ICU admission), or older patient (>60 years old) subgroups were examined. RBCs stored ≥35 days, however, were associated with increased morbidity for all patients, and for the sicker and older patient subgroups. Mortality was increased with ≥35 day RBCs, but only for the sicker patients. Length of stay was increased for both ≥28 day and ≥35 day RBCs, when all patients, and when both subgroups were examined.
In conclusion, RBCs stored ≥35 days, but not those stored ≥28 days are associated with increased morbidity. Regarding mortality, RBCs stored ≥35 days are problematic, but only when they are given to the sicker patients. Although recent prospective randomized trials have not shown increased RBC storage duration to be of concern, these studies did not include RBCs given at the end of their 42-day shelf life. The findings in this study suggest that giving the oldest blood in the bank (≥35 days) to the sickest patients in the hospital may worsen outcomes, but that “middle age” blood does not appear to be harmful.Steven M. Frank MD