Risks associated with red blood cell transfusion in the trauma population, a meta-analysis.

INTRODUCTION: A previous meta-analysis has found an association between red blood cell (RBC) transfusions and mortality in critically ill patients, but no review has focused on the trauma population only.

OBJECTIVES: To determine the association between RBC transfusion and mortality in the trauma population, with secondary outcomes of multiorgan failure (MOF) and acute respiratory distress syndrome (ARDS) or acute lung injury (ALI).

DATA SOURCES: EMBASE (1947-2012) and MEDLINE (1946-2012).

STUDY ELIGIBILITY CRITERIA: Randomized controlled trials and observational studies were to be included if they assessed the association between RBC transfusion and either the primary (mortality) or secondary outcomes (MOF, ARDS/ALI).

PARTICIPANTS: Trauma patients.

EXPOSURE: Red blood cell transfusion.

METHODS: A literature search was completed and reviewed in duplicate to identify eligible studies. Studies were included in the pooled analyses if an attempt was made to determine the association between RBC and the outcomes, after adjusting for important confounders. A random effects model was used for and heterogeneity was quantified using the I(2) statistic. Study quality was assessed using the Newcastle-Ottawa Scale.

RESULTS: 40 observational studies were included in the qualitative review. Including studies which adjusted for important confounders found the odds of mortality increased with each additional unit of RBC transfused (9 Studies, OR 1.07, 95%CI 1.04-1.10, I(2) 82.9%). The odds of MOF (3 studies, OR 1.08, 95%CI 1.02-1.14, I(2) 95.9%) and ARDS/ALI (2 studies, OR 1.06, 95%CI 1.03-1.10, I(2) 0%) also increased with each additional RBC unit transfused.

CONCLUSIONS: We have found an association between RBC transfusion and the primary and secondary outcomes, based on observational studies only. This represents the extent of the published literature. Further interventional studies are needed to clarify how limiting transfusion can affect mortality and other outcomes.