Older Red Blood Cells Pose Risks for Children

Major Finding: Transfusion of red blood cells stored 14 days or longer increases risk of multiple organ failure in critically ill children nearly twofold, compared with fresher RBCs.

Data Source: Secondary analysis of prospective, multicenter study of 296 patients.

Disclosures: Fonds de la Recherche en Santé du Québec sponsored this secondary analysis, planned a priori, of an initial, prospective, observational study funded by Johnson & Johnson. Dr. Karam disclosed that he has no financial conflict of interest.

MIAMI BEACH — A significantly higher rate of multiple organ failure after transfusion with red blood cells stored 14 days or longer, compared with fresher cells, has been shown for the first time in pediatric critical care patients.

“We were surprised to find such a difference—twice as many patients develop a bad outcome—which is very important for something so frequently used,” Dr. Oliver Karam said in an interview at his poster during the annual congress of the Society of Critical Care Medicine. The poster was selected as a Research Citation Finalist at the meeting.

Transfusions are probably one of the most common treatments in the severely ill pediatric population, he said. About one in every two children admitted to a postoperative intensive care unit (PICU) receives at least one transfusion.

Previous studies in adults and animals yielded conflicting results regarding the safety of older versus newer stored red blood cells, Dr. Karam said. Although a retrospective study of 67 transfused children found no difference in outcomes related to the shelf life of RBCs (Intensive Care Med. 2009;35:179–80), “this has not been answered [prospectively] yet in pediatrics. We are the only ones, to my knowledge, to look at pediatric data.”

Dr. Karam and his colleagues screened 930 consecutive patients younger than 18 years admitted to a PICU for 48 hours or longer at 1 of 29 centers in North America. Of the 447 children who received at least one transfusion, information on storage time was available for 296 patients. The median length of storage was 14 days, so this became the cutoff to define “older” versus “fresher” blood.

The maximum permitted length of storage in both the United States and Canada is 42 days, said Dr. Karam, chief medical fellow at CHU Sainte-Justine in Montreal.

Among patients who received blood stored 14 days or longer, the increased incidence of new or progressive multiple organ failure was almost double (adjusted odds ratio, 1.87), based on a multiple logistic regression that adjusted for gender, weight, number of organ failures at admission, total transfusion number, and total transfusion dose. Clinical severity at admission was associated with more RBC transfusions but not with use of older versus fresher blood, Dr. Karam said.

Although not significant, there was a trend for the older blood group to develop new or progressive multiple organ failure faster than the other patients (hazard ratio, 1.43).

Mortality over 28 days and PICU length of stay were secondary outcomes. There was no significant difference in this mortality rate between groups.

“The good news is pediatric patients do not die as much” as transfused adults in a critical care setting, Dr. Karam said. They generally have a greater resiliency and more functional reserve, which “may be why we did not see a difference in deaths.”

However, patients who received older blood stayed significantly longer in critical care—an adjusted median difference of 3.7 more days than did the fresher blood group. “We were surprised length of stay was so different—almost 4 days, which is huge and costs a lot,” he said.

“There are lots of hypotheses in the literature” about the effects of older stored RBCs, Dr. Karam said, such as activity by cytokines, active biolipids, or thrombotic factors. “It is probably a mix of things, but the clinical effect is there.”

Dr. Karam is planning a study to confirm these findings and look for possible mechanisms. “We are starting a pilot randomized, controlled study called ABC, or Age of Blood in Children.”

“We were surprised to find such a difference” in outcomes related to blood storage, Dr. Oliver Karam said.

Source DAMIAN McNAMARA/ELSEVIER GLOBAL MEDICAL NEWS

My Take

Transfusion Strategies for Children Merit More Study

These study findings are useful to hospitalists and all pediatricians who care for inpatients. A growing body of literature highlights the inherent risks of blood product transfusion. The majority of the work has been done in adult patients, and it is therefore crucial to closely examine the safety and effectiveness of transfusion strategies in children.