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Transfusion thresholds and other strategies for guiding allogeneic red blood cell transfusionHill S, Carless PA, Henry DA, Carson JL, Hebert PPC, Henderson KM, McClelland B
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SummarySafety of blood transfusion improved by the use of 'transfusion thresholds'Many people are given a transfusion of blood from an unrelated donor as part of their medical treatment. There are, however, risks involved. In particular, infections (including HIV and certain types of hepatitis) may be passed on to the person receiving the blood. This risk is small in richer countries but much larger in poor countries which lack good facilities to test the blood for infections. Because of the risks, doctors try to avoid giving blood unless it is really necessary. One approach is to give transfusion only if the amount of haemoglobin in the patient's blood has dropped below a certain 'threshold' level. The reviewers looked for controlled studies evaluating the effectiveness of this approach. They found ten, with a total of 1780 patients. The results, most of which came from just one study, support the use of transfusion thresholds. However, the reviewers say that more research is needed and that, until more is known, patients who have a serious heart problem should not be treated in this way. The reviewers conclude that, for most patients, blood transfusion is probably not essential until haemoglobin levels drop below 7.0 grammes per decilitre.
This is a Cochrane review abstract and plain language summary, prepared and maintained by The Cochrane Collaboration, currently published in The Cochrane Database of Systematic Reviews 2010 Issue 1, Copyright © 2010 The Cochrane Collaboration. Published by John Wiley and Sons, Ltd.. The full text of the review is available in The Cochrane Library (ISSN 1464-780X).
This version first published online:
April 22. 2002 AbstractBackgroundMost clinical practice guidelines recommend restrictive red cell transfusion practices, with the goal of minimising exposure to allogeneic blood (from an unrelated donor). The purpose of this review is to compare clinical outcomes in patients randomised to restrictive versus liberal transfusion thresholds (triggers). ObjectivesTo examine the evidence for the effect of transfusion thresholds on the use of allogeneic and/or autologous blood, and the evidence for any effect on clinical outcomes. Search strategyTrials were identified by: computer searches of OVID MEDLINE (1966 to November 2004), Current Contents (1993 to November 2004), and the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 3, 2004). References in identified trials and review articles were checked and authors contacted to identify any additional studies. Selection criteriaControlled trials in which patients were randomised to an intervention group or to a control group. Trials were included where intervention groups were assigned on the basis of a clear transfusion 'trigger', described as a haemoglobin (Hb) or haematocrit (Hct) level below which an RBC transfusion was to be administered. Data collection and analysisTrial quality was assessed using criteria proposed in Schulz 1995. Relative risks of requiring allogeneic blood transfusion, transfused blood volumes and other clinical outcomes were pooled across trials, using a random effects model. Main resultsTen trials were identified, reporting outcomes for a total of 1780 patients. Restrictive transfusion strategies reduced the risk of receiving a red blood cell (RBC) transfusion by a relative 42% (RR=0.58; 95%CI 0.47 to 0.71). This equates to an average absolute risk reduction (ARR) of 40% (95%CI 24% to 56%). The volume of RBCs transfused was reduced on average by 0.93 units (95%C 0.36 to1.5 units). However, heterogeneity between trials was statistically significant (P<0.00001) for these outcomes. Mortality, rates of cardiac events, morbidity, and length of hospital stay were unaffected. Trials were of poor methodological quality. Authors' conclusionsThe limited published evidence supports the use of restrictive transfusion triggers in patients who are free of serious cardiac disease. However, most of the data on clinical outcomes were generated by a single trial. The effects of conservative transfusion triggers on functional status, morbidity and mortality, particularly in patients with cardiac disease, need to be tested in further large clinical trials. In countries with inadequate screening of donor blood, the data may constitute a stronger basis for avoiding transfusion with allogeneic red cells. |