Duration of red cell storage before transfusion and in-hospital mortality

BACKGROUND: Red cell transfusions are lifesaving in severely anemic or acutely bleeding patients but may be associated with an increased risk of cardiovascular events in critically ill patients. The objective of the study was to examine the association between duration of pretransfusion storage of red cells and in-hospital mortality. METHODS: We used multivariable Cox regression modeling with time-dependent stratification to assess the effect of age of transfused red blood cells on risk of in-hospital mortality in a registry of consecutive patients admitted to an acute care facility with a major diagnosis of cardiovascular disease. RESULTS: Four thousand nine hundred thirty-three consecutive patients with a major diagnosis of cardiovascular disease admitted to acute care facilities in Hamilton, Canada, received 21,435 units of red cells. The median number of units received was 3 (interquartile range 2-5), and the median age of transfused blood was 17 (interquartile range 13-22) days. After adjustment for demographics, clinical characteristics, and time-dependent covariates and stratification by the number of units transfused, the relative risk for death was 1.02 for every 1-day increase in maximum age of blood. The adjusted relative risk for death increased with each increasing quartile of maximum age of blood, with patients in the highest quartile having a relative risk for death of 1.48 (95% CI 1.07-2.05) compared with those in the lowest (reference) quartile. CONCLUSIONS: In hospitalized patients with a major diagnosis of cardiovascular disease, there is a modest independent association between increasing duration of storage of red cells and risk of in-hospital mortality that appears to be continuous and graded.