Intravenous Iron Therapy for Patients With Preoperative Iron Deficiency or Anaemia Undergoing Cardiac Surgery Reduces Blood Transfusions: A Systematic Review and Meta-Analysis

Meta-analysis of 4 RCTs and 7 observational studies.
Observational studies suggest suggests a benefit of IV iron compared to no iron on mortality [relative risk 0.39, 95% confidence interval (CI) 0.23–0.65; P < 0.001, very low quality], units transfused per patient (mean difference −1.22, 95% CI −1.85 to −0.60; P < 0.001, very low quality), renal injury (relative risk 0.50, 95% CI 0.36–0.69; P < 0.001, very low quality) and hospital length of stay (mean difference −4.24 days, 95% CI −6.86 to −1.63; P = 0.001, very low quality). 
RCTs demonstrated a reduction in the number of patients transfused with IV iron compared to oral or no iron (relative risk 0.81, 95% CI 0.70–0.94; P = 0.005, moderate quality). The pooled estimates of effect from RCTs for mortality, hospital length of stay, units transfused per patient and renal injury were consistent in direction with observational studies.
IV iron may improve postoperative morbidity in adult cardiac surgery patients with preoperative anaemia or iron deficiency. A large, rigorous, placebo-controlled, double-blinded, multicentre trial is needed to clarify the role of IV iron in this patient population.