Age of Red Blood Cell Units Transfused in Canada.

During storage, red blood cells (RBCs) undergo well-described biochemical and biomechanical changes, termed the red cell storage lesion. These changes may affect the ability of stored RBCs to deliver oxygen or have other adverse consequences. The transfusion of older RBCs has been associated with increased morbidity/mortality, and planned or on-going randomized controlled trials are exploring a possible causal relationship between the age of RBCs and mortality/morbidity. However, the age-related characteristics of the RBCs units in hospital inventories and of the RBCs units transfused are largely unknown.

A descriptive observational study from 9 centres from 5 Canadian provinces was conducted. Using a randomly generated schedule, data was collected on one weekday for 30 consecutive weeks. Reports of the RBCs inventories and the transfused RBCs units for all ABO and Rh blood groups were collected and analyzed.

Academic centers contributed more than half of the collected data, both for inventory and for transfused units. Overall, the median age of RBCs units in inventory was 14 days (IQR=10-20) and their median age upon transfusion was 16 days (IQR=12-22). The cumulative proportion of younger blood (less than 8 days) in inventory was 9% (range for individual centres: 5 to 20%) for units in inventory and 5% (range for individual centres: 1 to 17%) for transfused units. The cumulative proportion of older blood (more than 28 days) was 8% (range for individual centres: 6 to 14%) for units in inventory, and 13% (range for individual centres: 9 to 23%) for transfused units. Community centres tended to have the largest proportion of younger units transfused (12%) as well as in inventory (14%).

This study provides important data that may contribute to decision-making regarding blood bank inventory management and age-based transfusion practices. If the results of ongoing studies demonstrate an adverse effect from transfusing older RBCs, then significant changes to the inventory management may be required. In Canada, shortening the shelf-life for storage of RBC units to 28 days may be less problematic, but restricting the age of RBCs transfused to less than 8 days for all RBC units may pose significant challenges.

Tinmouth:Canadian Blood Services: Consultancy; Novartis: Research Funding; CSL: Research Funding; Bayer: Research Funding; Wyeth: Research Funding.