Characterizing red blood cell age exposure in massive transfusion therapy: the scalar age of blood index (SBI)

• Published in: Transfusion (Philadelphia, Pa.) Vol. 59; no. 8; pp. 2699 - 2708
• Main Authors: DeSantis, Stacia M., Brown, Derek W., Jones, Allison R., Yamal, Jose‐Miguel, Pittet, Jean‐Francois, Patel, Rakesh P., Wade, Charles E., Holcomb, John B., Wang, Henry
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.08.2019; Wiley Subscription Services, Inc
• Subjects: Adult; Age; Age composition; Bleeding; Blood; Blood Preservation; Disease-Free Survival; Erythrocyte Transfusion; Erythrocytes; Exposure; Female; Hemorrhage; Hemorrhagic shock; Humans; Male; Middle Aged; Mortality; Randomization; Secondary analysis; Shock, Hemorrhagic - blood; Shock, Hemorrhagic - mortality; Shock, Hemorrhagic - therapy; Survival Rate; Time Factors; Transfusion; Trauma; Wounds and Injuries - blood; Wounds and Injuries - mortality; Wounds and Injuries - therapy
• ISSN: 0041-1132; 1537-2995
• DOI: 10.1111/trf.15334

BACKGROUND The mortality of trauma patients requiring massive transfusion to treat hemorrhagic shock approaches 17% at 24 hours and 26% at 30 days. The use of stored RBCs is limited to less than 42 days, so older RBCs are delivered first to rapidly bleeding trauma patients. Patients who receive a greater quantity of older RBCs may have a higher risk for mortality. METHODS AND MATERIALS Characterizing blood age exposure requires accounting for the age of each RBC unit and the quantity of transfused units. To address this challenge, a novel Scalar Age of Blood Index (SBI) that represents the relative distribution of RBCs received is introduced and applied to a secondary analysis of the Pragmatic, Randomized Optimal Platelet and Plasma Ratios (PROPPR) randomized controlled trial (NCT01545232, https://clinicaltrials.gov/ct2/show/NCT01545232). The effect of the SBI is assessed on the primary PROPPR outcome, 24‐hour and 30‐day mortality. RESULTS The distributions of blood storage ages successfully maps to a parameter (SBI) that fully defines the blood age curve for each patient. SBI was a significant predictor of 24‐hour and 30‐day mortality in an adjusted model that had strong predictive ability (odds ratio, 1.15 [1.01‐1.29], p = 0.029, C‐statistic, 0.81; odds ratio, 1.14 [1.02‐1.28], p = 0.019, C‐statistic, 0.88, respectively). CONCLUSION SBI is a simple scalar metric of blood age that accounts for the relative distribution of RBCs among age categories. Transfusion of older RBCs is associated with 24‐hour and 30‐day mortality, after adjustment for total units and clinical covariates.