Transfusion medicine reviews
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No up-to-date overview of randomized controlled trials (RCTs) in red blood cell (RBC) transfusion exists. This systematic review examines the quantity and quality of the evidence for the clinical effects of RBC transfusion. One hundred forty-two eligible RCTs were identified through searches of The Cochrane Library (issue 4, 2009), MEDLINE (1950 to November 2009), EMBASE (1974 to November 2009), and other relevant sources. ⋯ Clinical areas with few trials are highlighted. Comparison with a study of RBC use in clinical practice highlighted a lack of correlation between the size of the evidence base for a given clinical specialty and the proportion of total RBC use by that clinical specialty. The gaps in the evidence base and the poor methodology of trials particularly in the past do not provide a strong evidence base for the use of RBC transfusions, but they indicate important targets for future research.
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The transfusion of allogeneic red blood cells (RBCs) and other blood components is ingrained in modern medical practice. The rationale for administering transfusions is based on key assumptions that efficacy is established and risks are acceptable and minimized. Despite the cliché that, "the blood supply is safer than ever," data about risks and lack of efficacy of RBC transfusions in several clinical settings have steadily accumulated. ⋯ On the other hand, when several possible interacting risk factors exist and RBC transfusions are associated with adverse clinical outcomes, establishing causation requires inferential probabilistic methodology. In the latter circumstances, the case for RBC transfusions being causal for adverse clinical outcomes can be strengthened by applying modified Bradford Hill criteria to the plethora of existing observational studies. This being the case, a greater precautionary approach to RBC transfusion is necessary and equipoise that justifying RCTs may become problematic.
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Editorial Comment
Establishing causation in transfusion medicine and related tribulations.