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Iron supplementation for patients undergoing cardiac surgery: a systematic review and meta-analysis of randomized controlled trials

Can J Anaesth. 2022 Jan;69(1):129-139 doi: 10.1007/s12630-021-02113-z.
PICO Summary

Patients undergoing cardiac surgery (5 studies, n= 554).


Iron therapy.


Placebo, or no-treatment.


Based on the pooling of data from four trials (n= 449), the use of iron showed no statistical difference in the incidence of transfusion (RR, 0.86). There was low heterogeneity between studies (I2 = 0%). One trial (n= 60) reported a significant decrease in the number of red blood cells transfused (mean differences, -1.0 units). All five trials (n= 554) showed no difference in serious adverse events using iron therapy (risk difference, 0.0).


Iron supplementation has been evaluated in several randomized controlled trials (RCTs) for its potential to increase baseline hemoglobin and decrease red blood cell transfusion during cardiac surgery. This study's main objective was to evaluate the current evidence for iron administration in cardiac surgery patients.


We searched MEDLINE, EMBASE, CENTRAL, Web of Science databases, and Google Scholar from inception to 19 November 2020 for RCTs evaluating perioperative iron administration in adult patients undergoing cardiac surgery. The RCTs were assessed using a risk of bias assessment and the quality of evidence was assessed using the grading of recommendations, assessments, development, and evaluations.


We reviewed 1,767 citations, and five studies (n = 554) met the inclusion criteria. The use of iron showed no statistical difference in incidence of transfusion (risk ratio, 0.86; 95% confidence interval, 0.65 to 1.13). Trial sequential analysis suggested an optimal information size of 1,132 participants, which the accrued information size did not reach.


The current literature does not support or refute the routine use of iron therapy in cardiac surgery patients.


PROSPERO (CRD42020161927); registered 19 December 2019.

KEYWORDS: Anemia; Blood transfusion; Cardiac surgery; Iron
MESH HEADINGS: Adult; Anemia; Cardiac Surgical Procedures; Dietary Supplements; Humans; Iron; Randomized Controlled Trials as Topic
Study Details
Study Design: Systematic Review
Language: eng
Credits: Bibliographic data from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine