R. Uhlich1, R. Patel1, J. Pittet1, P. Bosarge1, M. Marques1, H. Wang1, J. Kerby1 1UAB,Acute Care Surgery,Birmingham, AL, USA
Introduction:
Numerous studies have examined the association between blood age and mortality among trauma patients. This study was designed to account for the time-varying nature of exposure to stored blood and its effect on mortality.
Methods:
Patients receiving at least one unit of red blood cells between 2011 and 2014 were included. Blood bank data was queried for the age of blood and time of transfusion. Demographics, injury, and clinical characteristics were obtained from the trauma registry. The time at which a patient received at least one unit of blood stored > 7 days, > 14 days, or > 21 days was calculated. A Cox proportional hazards model adjusted for age, Injury Severity Score, and injury mechanism estimated hazard ratios (HRs) for the association between death in 24 hours and receiving at least one unit of stored blood. A separate model was created for each blood age category, and exposure to at least one unit of stored blood was entered as a time-varying covariate. Models were stratified by whether the patient received > 10 units of blood in 24 hours.
Results:
1,654 patients received at least one unit of PRBC (187 massively transfused). Increased hazard of 24-hour mortality was observed for those with exposure to at least one unit of blood > 7 days (HR 1.83, 95% CI 1.31-2.56), > 14 days (HR 1.49, 95% CI 1.05-2.10), or > 21 days (HR 1.75, 95% CI 1.17-2.62). The hazard increased when patients received at least 4 units of blood > 14 days (HR 3.54, 95% CI 2.20-5.71) or 21 days (HR 5.21, 95% CI 2.53-10.76). Patterns of association were observed among massively transfused patients.
Conclusion:
Exposure to increasing number and age of stored blood increases the hazard of 24-hour mortality for patients requiring large blood volume replacement. Clinical trials evaluating the effect of blood storage age on clinical outcomes in trauma are warranted.