Should Transfusion Trigger Thresholds Differ for Critical Care Versus Perioperative Patients? A Meta-Analysis of Randomized Trials

Objective: To address the significant uncertainty as to whether transfusion thresholds for critical care versus surgical patients should differ. Design: Meta-analysis of randomized controlled trials. Setting: Medline, EMBASE, and Cochrane Library searches were performed up to 15 June 2016. Patients: Trials had to enroll adult surgical or critically ill patients for inclusion. Interventions: Studies had to compare a liberal versus restrictive threshold for the transfusion of allogeneic packed RBCs. Measurements and Main Results: The primary outcome was 30-day all-cause mortality, sub-grouped by surgical and critical care patients. Secondary outcomes included myocardial infarction, stroke, renal failure, allogeneic blood exposure, and length of stay. Odds ratios and weighted mean differences were calculated using random effects meta-analysis. To assess whether subgroups were significantly different, tests for subgroup interaction were used. Subgroup analysis by trials enrolling critically ill versus surgical patients was performed. Twenty-seven randomized controlled trials (10,797 patients) were included. In critical care patients, restrictive transfusion resulted in significantly reduced 30-day mortality compared with liberal transfusion (odds ratio, 0.82; 95% CI, 0.70–0.97). In surgical patients, a restrictive transfusion strategy led to the opposite direction of effect for mortality (odds ratio, 1.31; 95% CI, 0.94–1.82). The subgroup interaction test was significant (p = 0.04), suggesting that the effect of restrictive transfusion on mortality is statistically different for critical care (decreased risk) versus surgical patients (potentially increased risk or no difference). Regarding secondary outcomes, for critically ill patients, a restrictive strategy resulted in reduced risk of stroke/transient ischemic attack, packed RBC exposure, transfusion reactions, and hospital length of stay. In surgical patients, restrictive transfusion resulted in reduced packed RBC exposure. Conclusions: The safety of restrictive transfusion strategies likely differs for critically ill patients versus perioperative patients. Further trials investigating transfusion strategies in the perioperative setting are necessary. This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. Dr. Chong extracted the data, performed the data analysis, created the figures/tables, and prepared the article. Contribution: Dr. Krishnan extracted the data, performed the data analysis, created the figures/tables, and revised the article. Dr. Cheng provided resource support in this study, guidance with article preparation, and revised the final article. Dr. Martin conceived the idea of performing a meta-analysis of transfusion triggers, provided guidance with article preparation and data analysis, and revised the final article. All authors attest to the integrity of the original data and analysis, as well as approved the final article. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's website (http://ift.tt/29S62lw). The authors have disclosed that they do not have any potential conflicts of interest. For information regarding this article, E-mail: janet.martin@lhsc.on.ca Copyright © by 2017 by the Society of Critical Care Medicine and Wolters Kluwer Health, Inc. All Rights Reserved.

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