Systematic reviews and meta-analyses comparing mortality in restrictive and liberal haemoglobin thresholds for red cell transfusion: an overview of systematic reviews

School of Population and Global Health, The University of Western Australia, Perth, Australia: Kevin.Trentino@uwa.edu.au Data and Digital Innovation, East Metropolitan Health Service, Perth, Australia: Kevin.Trentino@uwa.edu.au Medical School and Division of Surgery, The University of Western Australia, Perth, Australia. School of Health Sciences and Graduate Studies, Curtin University, Bentley, Australia. Department of Haematology, PathWest Laboratory Medicine, Royal Perth Hospital, Perth, Australia. Medical School, The University of Western Australia, Perth, Australia. School of Population and Global Health, The University of Western Australia, Perth, Australia. School of Medicine, The University of Sydney, Sydney, Australia. Library and Information Service, South Metropolitan Health Service, Murdoch, Australia. Institute of Anesthesiology, University Hospital Zurich, Zurich, Switzerland. Department of Anesthesiology, Englewood Hospital and Medical Center, TeamHealth Research Institute New Jersey, Englewood, USA. Australian and New Zealand Intensive Care Research Centre, Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia.

BMC Med. 2020;18(1):154
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PICO Summary

Population

Patients assigned to red cell transfusion strategies based on haemoglobin thresholds (19 studies).

Intervention

Restrictive transfusion strategy.

Comparison

Liberal transfusion strategy.

Outcome

Of the meta-analyses presenting high- to moderate-quality evidence, 12 reported no statistically significant difference in mortality between restrictive and liberal transfusion groups and 4 reported significantly lower mortality for patients assigned to a restrictive transfusion strategy. Few systematic reviews addressed clinical differences between included studies: variation was observed in haemoglobin threshold concentrations, the absolute between group difference in haemoglobin threshold concentration, time to randomisation, and transfusion dosing regimens.
Abstract
BACKGROUND There are no overviews of systematic reviews investigating haemoglobin thresholds for transfusion. This is important as the literature on transfusion thresholds has grown considerably in recent years. Our aim was to synthesise evidence from systematic reviews and meta-analyses of the effects of restrictive and liberal transfusion strategies on mortality. METHODS This was a systematic review of systematic reviews (overview). We searched MEDLINE, Embase, Web of Science Core Collection, PubMed, Google Scholar, and the Joanna Briggs Institute EBP Database, from 2008 to 2018. We included systematic reviews and meta-analyses of randomised controlled trials comparing mortality in patients assigned to red cell transfusion strategies based on haemoglobin thresholds. Two independent reviewers extracted data and assessed methodological quality. We assessed the methodological quality of included reviews using AMSTAR 2 and the quality of evidence pooled using an algorithm to assign GRADE levels. RESULTS We included 19 systematic reviews reporting 33 meta-analyses of mortality outcomes from 53 unique randomised controlled trials. Of the 33 meta-analyses, one was graded as high quality, 15 were moderate, and 17 were low. Of the meta-analyses presenting high- to moderate-quality evidence, 12 (75.0%) reported no statistically significant difference in mortality between restrictive and liberal transfusion groups and four (25.0%) reported significantly lower mortality for patients assigned to a restrictive transfusion strategy. We found few systematic reviews addressed clinical differences between included studies: variation was observed in haemoglobin threshold concentrations, the absolute between group difference in haemoglobin threshold concentration, time to randomisation (resulting in transfusions administered prior to randomisation), and transfusion dosing regimens. CONCLUSIONS Meta-analyses graded as high to moderate quality indicate that in most patient populations no difference in mortality exists between patients assigned to a restrictive or liberal transfusion strategy. TRIAL REGISTRATION PROSPERO CRD42019120503.
Study details
Study Design : Systematic Review
Language : eng
Credits : Bibliographic data from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine