ABSTRACT
BACKGROUND: Preoperative screening for iron deficiency is a part of patient blood management protocols. This systematic review, meta-analysis, and meta-regression reviews the association between nonanemic iron deficiency and postoperative outcomes in patients undergoing cardiac surgery. We aimed to determine whether preoperative screening for nonanemic iron deficiency should be recommended in patients undergoing cardiac surgery. METHODS: Electronic databases MEDLINE (Ovid), Embase (Ovid), and Scopus were searched from inception until December 9, 2022. Studies were considered for inclusion if they (1) used an observational study design; (2) enrolled adult patients undergoing cardiac surgery; and (3) included an iron-deficient and iron-replete group, defined using serum ferritin and/or transferrin saturation. The primary outcome was the length of acute hospital stay. Secondary outcomes included length of intensive care unit stay, requirement for allogeneic red blood cell transfusion, number of red blood cell units transfused, days alive and at home at postoperative days 30 and 90, all-cause postoperative complications, postoperative infection, mortality, and hospital readmission. Meta-regression was performed to assess the effects of study and patient-level factors on the associations between nonanemic iron deficiency and specific outcomes. Individual study quality was assessed using the Risk of Bias in Non-Randomized Studies of Exposures (ROBINS-E) tool. The Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) framework was used to determine the quality of evidence for each outcome. RESULTS: Eight studies (2683 patients) were included. No significant association was observed between nonanemic iron deficiency and any of the primary or secondary outcomes except for an increased requirement for allogeneic red blood cell transfusion (odds ratio [OR], 1.39 [95% confidence interval, CI, 1.16-1.68; P < .001; I2 2.8%]). Meta-regression did not identify any potential sources of heterogeneity to explain variation in individual study results. The quality of evidence was rated as "low" or "very low" for all outcomes. CONCLUSIONS: Few high-quality studies are available to assess associations between nonanemic iron deficiency and outcomes after cardiac surgery. Acknowledging these limitations, the presence of preoperative nonanemic iron deficiency was not associated with a change in the primary outcome of length of hospital stay, or any patient-centered secondary outcome compared to those without iron deficiency. There was an association with increased requirement for allogeneic red blood cell transfusion, but this did not impact the reported patient-centered outcomes.
Subject(s)
Cardiac Surgical Procedures , Postoperative Complications , Humans , Cardiac Surgical Procedures/adverse effects , Cardiac Surgical Procedures/mortality , Postoperative Complications/etiology , Postoperative Complications/blood , Postoperative Complications/mortality , Postoperative Complications/diagnosis , Postoperative Complications/epidemiology , Treatment Outcome , Length of Stay , Anemia, Iron-Deficiency/blood , Anemia, Iron-Deficiency/diagnosis , Risk Factors , Iron Deficiencies , Erythrocyte Transfusion/adverse effects , Iron/blood , Female , MaleABSTRACT
INTRODUCTION: Preoperative anaemia is associated with poor postoperative outcomes and is the strongest predictor of allogenic blood transfusion, which contributes further to patient morbidity. Emphasis has been placed on correcting anaemia prior to surgery to mitigate these outcomes. Conflicting evidence exists regarding the benefit of currently recommended interventions. With greater understanding of iron haemostasis and erythropoiesis, novel therapies have been identified. These are at varying stages of development with some demonstrating promising results in patients with chronic kidney disease. It is not known how these agents have been studied outside this population, particularly in the perioperative context. To address this, we will conduct a scoping review of the published literature to chart the evidence. METHODS AND ANALYSIS: The scoping review will be reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews framework. The electronic database search will include Scopus, MEDLINE (Ovid) and Excerpta Medica database (Ovid), with no language restrictions, and will include all publications since 1 January 2010. This review will have three objectives: (1) to describe the mechanisms of action for novel agents, (2) to describe the level of evidence and stage of development of novel agents in a perioperative setting, and (3) to determine the potential agents suitable for prospective controlled trials in a preoperative or postoperative patient cohort and aiming to improve patient-centred outcomes. The review process will involve two reviewers with a third reviewer resolving disagreements. Data will be extracted and organised with subsequent analysis. ETHICS AND DISSEMINATION: This scoping review does not require research ethics approval. The results will be published in a peer-reviewed journal and inform the development of future prospective trials based on established evidence from potential therapeutic agents. TRIAL REGISTRATION NUMBER: This protocol has been registered prospectively on the Open Science Framework registry (DOI:10.17605/OSF.IO/SM3UH, https://osf.io/sm3uh/?view_only=39876ccf7a4348dfbd566535b957a7db).Cite Now.
