Transfusion thresholds and other strategies for guiding red blood cell transfusion
Abstract
Background
The optimal haemoglobin threshold for use of red blood cell (RBC) transfusions in anaemic patients remains an active area of research. Blood is a limited resource, and there are concerns about risks, including transmitted infections. If a liberal transfusion strategy does not improve clinical outcomes, or if it is equivalent, then adopting a more restrictive approach should be recognised as the standard of care.
Objectives
The aim of this review update was to compare 30‐day mortality and other clinical outcomes for participants randomised to restrictive versus liberal red blood cell (RBC) transfusion thresholds (triggers) for all clinical conditions. The restrictive transfusion threshold uses a lower haemoglobin concentration as a threshold for transfusion (most commonly, 7.0 g/dL to 8.0 g/dL), and the liberal transfusion threshold uses a higher haemoglobin concentration to direct transfusion (most commonly, 9.0 g/dL to 10.0 g/dL). Increasingly, investigators are considering other strategies including physiological triggers (i.e. central venous oxygen saturation), alone or in combination with such thresholds, to determine when a transfusion is indicated, so it is important to assess this growing body of evidence in tandem.
Search methods
We searched CENTRAL, MEDLINE, Embase, Transfusion Evidence Library, Web of Science Conference Proceedings Citation Index, trial registries and PubMed on 14 October 2024. We checked reference lists of published reviews and papers for additional trials.
Selection criteria
We included randomised trials of surgical or medical participants that recruited adults or children. We excluded studies that focused on preterm neonates. Eligible trials assigned intervention groups based on different transfusion strategies or thresholds, usually defined by a haemoglobin concentration below which a RBC transfusion would be administered. We included trials in which investigators had allocated participants to higher thresholds or more liberal transfusion strategies compared to more restrictive ones, which might include no transfusion.
Data collection and analysis
We used standard Cochrane methods. We pooled risk ratios across trials using a random‐effects model. We assessed risk of bias using the Cochrane RoB 1 tool, and assessed the certainty of evidence using GRADE. We defined participants randomly allocated to the lower transfusion threshold as being in the ‘restrictive transfusion’ group and those randomly allocated to the higher transfusion threshold as being in the ‘liberal transfusion’ group.