Blood transfusion through the lens of Evidence-Based Medicine

Abstract

Introduction: Blood transfusion is a traditional, popular treatment and considered by society and the medical community as a treatment that has great benefits in reducing mortality. Evidence-based medicine is an approach to medical practice that aims at making decisions based on up-to-date scientific evidence tested by the scientific method. The objective of this study was to evaluate blood transfusion through the lens of evidence-based medicine. Methods: Non-systematic search of the literature, without restriction of type of study, date or language, in the scientific databases: MEDLINE, LILACS, EMBASE, Cochrane Library, SciELO, Scopus and Web of Science, prioritizing publication of systematic reviews and meta-analysis. Results: Systematic review of randomized clinical trials showed that more restrictive blood transfusion reduces mortality when compared to less restrictive transfusions. No randomized placebo-controlled clinical trials evaluating the efficacy of blood transfusion were found, setting up an uncertainty of the effect of both restrictive and liberal blood transfusion on mortality. Systematic review of the quality of guidelines on blood transfusion showed that the guidelines were carried out with low methodological rigor. Systematic review concluded that most studies did not demonstrate improvement of tissue oxygenation with blood transfusion. Systematic reviews of observational studies demonstrated an association of blood transfusion with increased mortality and all Bradford Hill causality criteria were met pointing to a causal relationship between blood transfusion and increased adverse outcomes. Systematic reviews have shown that both patients and physicians tend to overestimate the true benefits of treatments and underestimate their harms. Conclusion: The scientific evidence base for recommending blood transfusion is weak, with no robust evidence that the treatment reduces mortality. There is a significant accumulation of evidence showing worse clinical outcome with this treatment, revealing clear disagreement on how this treatment is perceived by society and the medical community. This leads to ethical and legal implications related to the quality of information that is offered to patients to obtain their informed consent and respect for their autonomy regarding the use of this treatment. The medical and legal communities, as well as society, should urgently re-evaluate blood transfusion under the principles of evidence-based medicine.