Hospitalized patients enrolled across four countries in the Informing Fresh versus Old Red Cell Management (INFORM) trial (n= 14,461).
Transfusion with freshest available erythrocyte units (n= 4,777).
Transfusion with oldest available erythrocyte units (n= 9,684).
The median of the mean age of blood units transfused per patient was 11 days in the freshest available blood group and 23 days in the oldest available blood group. In the primary analysis, post-transfusion acute kidney injury was observed in 688 of 4,777 (14.4%) patients given the freshest available blood and 1,487 of 9,684 (15.4%) patients given the oldest available blood, with an estimated relative risk of 0.94.