Anemia is highly prevalent among children hospitalized in pediatric intensive care units. Transfusion with red blood cells is the only way to treat severe anemia that could be life-threatening rapidly. Red blood cells are stored in blood banks as red-cell units for up to 42 days. Some studies published over the past few decades have suggested that transfusion with red-blood-cell units stored for longer periods might be less beneficial than transfusion with fresher red-cell units.
The study, one of the largest clinical trials to investigate red-blood-cell storage for critically ill children, sheds light on a controversial and neglected aspect of transfusion medicine. The study was funded by the Canadian Institutes of Health Research (CIHR) in Canada, by the National Heart, Lung, and Blood Institute (NHLBI) in the U.S., by the Programme Hospitalier de Recherche Clinique (PHRC) in France and by the Quebec Ministry of Health.
The study was led by two principal investigators: Dr. Marisa Tucci of Sainte-Justine and Dr. Philip Spinella of Washington University; both are pediatric intensivists and researchers. According to the investigators, the findings indicate that doctors who care for children in pediatric critical-care units should not be afraid to use older red cells in their patients. The results from this study suggest that those who systematically request fresh red cells should consider discontinuing this practice unless there are extenuating circumstances. The findings also provide good news for blood banks, who will likely feel less pressure to respond to requests for fresh red cells.
Red blood cell transfusions are commonly administered in critically ill children who have illnesses that increase the need for transfusions, such as trauma, cancer chemotherapy, major surgery with significant intraoperative bleeding, and conditions such as sickle cell disease and thalassemia. Transfusing the oldest red cells in the stored inventory first is standard practice among many hospitals to avoid wastage. However, some hospitals preferentially give fresh red blood cells to critically ill children, even though clinical studies supporting the benefits of this practice have been lacking.
To help fill the research gap, the investigators of the 'Age of Blood in Children in Pediatric Intensive Care Units' (ABC-PICU) study undertook a randomized trial that recruited patients admitted to pediatric intensive care units in 50 medical centers. The study began in February 2014 and ended in November 2018; 1,461 children ranging in age from 3 days to 16 years who were admitted to pediatric intensive care units were recruited in the United States (29 sites), Canada (10 sites), France (8 sites), Italy (2 sites), and Israel (1 site); Sainte-Justine University Hospital was the coordinating center in Canada and recruited the greatest number of patients (over 160). Data management and analysis were done by Dr. Dean Fergusson of the Centre for Practice-Changing Research at the University of Ottawa, in coordination with Drs. Tucci and Spinella.
During the course of the study, half of the patients received transfusions with fresh red blood cells stored for seven days or less, and half received transfusions with older red cells. The primary outcome measured was the development of new or progressive multiple organ dysfunctions (impairment of one or more organs). The researchers found that fresh red cells did not reduce the incidence of new or progressive multiple organ dysfunction or death compared to older red cells and that the outcomes were not significantly different between the two groups. About 20.2 percent of those who received fresh red cells experienced new or progressive organ dysfunction while 18.2 percent of those who received older red cells experienced similar dysfunction.
The relatively large number of patients recruited and their geographic diversity, as well as the inclusion of a wide variety of patients, were among the study's strengths, making it reasonable for researchers to generalize the findings to a larger pediatric population. The researchers did note some caveats, however. The study did not examine whether the use of the oldest red cells allowable (more than 35 days) affects outcomes, or whether fresh red cells affect outcomes for children requiring large-volume red cell transfusions. The children in this study received low-volume red cell transfusions.
The results of this study are applicable to the vast majority of children in pediatric intensive care units and show that current red-blood-cell transfusion practices are safe.