The authors conducted a retrospective cohort study of 405,000 transfusion episodes in Scandinavia over seven years in order to determine whether storage of transfused red blood cells (RBC) affected mortality. They found a small but significant difference in all-cause mortality with 2-year follow-up: patients who received RBCs aged 30-42 days had a 5% higher mortality rate than patients transfused with RBCs aged 10-19 days.
The authors conclude that this small excess mortality is more consistent with weak confounding factors than with a true storage effect.
This reviewer, however has a different take on the study: the small but significant effect was observed across all clinical settings being included in the study. Furthermore, such a storage effect may have been more powerfully demonstrated if the ‘younger’ cohort of RBC units had been 7-14 days rather than 10-19 days. Definitive studies to rule out a true storage lesion should focus on a comparison cohort of the freshest RBCs possible.
– Lawrence Tim Goodnough