Evidence-based practice of transfusion medicine: is it possible and what do the words mean?

Evidence-based medicine (EBM) optimizes clinical decision making by dictating that clinical decisions be based on the best available research evidence and by integrating best research evidence with clinical expertise and patient values. Several rankings of the strength of the evidence generated from different types of clinical research designs have been presented, and, in addressing a particular problem, clinicians can base their decision making on the types of clinical reports that have been published, along with an assessment of the strengths and weaknesses of each study. At a policy level, the concept of EBM would dictate that policy decisions also be made based on the best available research evidence. In transfusion medicine, however, decisions are based on a broader range of inputs, and the criteria for evaluating the efficacy and/or cost-effectiveness of proposed interventions differ from those used in other areas. Reasons why policy decisions are often based on considerations other than the best research evidence include public expectations about transfusion safety and proposals for applying the precautionary principle to transfusion medicine. Using the debate over the appropriateness of introducing universal white-cell reduction as an example, this review describes 2 perspectives for assessing evidence and/or making clinical or policy decisions: the evidence-based approach and the precautionary-principle approach; and also considers whether decisions in transfusion medicine can be truly evidence based.