The impact of perioperative iron on the use of red blood cell transfusions in gastrointestinal surgery: a systematic review and meta-analysis.

Perioperative anemia is common, yet detrimental, in surgical patients. However, red blood cell transfusions (RBCTs) used to treat anemia are associated with significant postoperative risks and worse oncologic outcomes. Perioperative iron has been suggested to mitigate perioperative anemia. This meta-analysis examined the impact of perioperative iron compared to no intervention on the need for RBCT in gastrointestinal surgery. We systematically searched Medline, Embase, Web of Science, Cochrane Central, and Scopus to identify relevant randomized controlled trials (RCTs) and nonrandomized studies (NRSs). We excluded studies investigating autologous RBCT or erythropoietin. Two independent reviewers selected the studies, extracted data, and assessed the risk of bias using the Cochrane tool and Newcastle-Ottawa scale. Primary outcomes were proportion of patients getting allogeneic RBCT and number of transfused patient. Secondary outcomes were hemoglobin change, 30-day postoperative morbidity and mortality, length of stay, and oncologic outcomes. A meta-analysis using random effects models was performed. The review was registered in PROSPERO (CRD42013004805). From 883 citations, we included 2 RCTs and 2 NRSs (n = 325 patients), all pertaining to colorectal cancer surgery. Randomized controlled trials were at high risk for bias and underpowered. One RCT and 1 NRS using preoperative oral iron reported a decreased proportion of patients needing RBCT. One RCT on preoperative intravenous iron and 1 NRS on postoperative PO iron did not observe a difference. Only 1 study revealed a difference in number of transfused patients. One RCT reported significantly increased postintervention hemoglobin. Among 3 studies reporting length of stay, none observed a difference. Other secondary outcomes were not reported. Meta-analysis revealed a trend toward fewer patients requiring RBCT with iron supplementation (risk ratio, 0.66 [0.42, 1.02]), but no benefit on the number of RBCT per patient (weighted mean difference, -0.91 [-1.61, -0.18]). Although preliminary evidence suggests that it may be a promising strategy, there is insufficient evidence to support the routine use of perioperative iron to decrease the need for RBCT in colorectal cancer surgery. Well-designed RCTs focusing on the need for RBCT and including long-term outcomes are warranted.