Age of red blood cells and mortality in the critically ill
1 Australian and New Zealand Intensive Care Research Centre, Department of Epidemiology and Preventive Medicine, Monash University, Commercial Road, Melbourne 3004, Victoria, Australia
2 Department of Intensive Care and Hyperbaric Medicine, The Alfred Hospital, Commercial Road, Melbourne 3004, Victoria, Australia
3 Australian Red Cross Blood Service, St Kilda Road, Melbourne 3004, Victoria, Australia
4 Transfusion Outcomes Research Collaborative, Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Commercial Road, Melbourne 3004, Victoria, Australia
5 Haematology Unit, The Alfred Hospital, Commercial Road, Melbourne 3004, Victoria, Australia
6 Department of Intensive Care, Western Health, Gordon Street, Fitzroy 3011, Victoria, Australia
7 Department of Intensive Care, The Geelong Hospital, Ryrie Street, Geelong 3220, Victoria, Australia
8 Intensive Care Unit, St Vincent's Hospital, Victoria Parade, Fitzroy 3065, Victoria, Australia
Critical Care 2011, 15:R116 doi:10.1186/cc10142Published: 15 April 2011
In critically ill patients, it is uncertain whether exposure to older red blood cells (RBCs) may contribute to mortality. We therefore aimed to evaluate the association between the age of RBCs and outcome in a large unselected cohort of critically ill patients in Australia and New Zealand. We hypothesized that exposure to even a single unit of older RBCs may be associated with an increased risk of death.
We conducted a prospective, multicenter observational study in 47 ICUs during a 5-week period between August 2008 and September 2008. We included 757 critically ill adult patients receiving at least one unit of RBCs. To test our hypothesis we compared hospital mortality according to quartiles of exposure to maximum age of RBCs without and with adjustment for possible confounding factors.
Compared with other quartiles (mean maximum red cell age 22.7 days; mortality 121/568 (21.3%)), patients treated with exposure to the lowest quartile of oldest RBCs (mean maximum red cell age 7.7 days; hospital mortality 25/189 (13.2%)) had an unadjusted absolute risk reduction in hospital mortality of 8.1% (95% confidence interval = 2.2 to 14.0%). After adjustment for Acute Physiology and Chronic Health Evaluation III score, other blood component transfusions, number of RBC transfusions, pretransfusion hemoglobin concentration, and cardiac surgery, the odds ratio for hospital mortality for patients exposed to the older three quartiles compared with the lowest quartile was 2.01 (95% confidence interval = 1.07 to 3.77).
In critically ill patients, in Australia and New Zealand, exposure to older RBCs is independently associated with an increased risk of death.