INTRAVENOUS IRON FOR PRE-OPERATIVE ANEMIA IN CARDIAC SURGERY PATIENTS: A PROMISING TREATMENT FOR A COMMON PROBLEM

Abstract

Cardiac surgery patients with preoperative anemia are at increased risk for mortality and morbidity. However, the benefits of treating preoperative anemia with intravenous (IV) iron have not been well-established. As such, we performed a systematic review and meta-analysis to determine the effects of IV iron therapy in adult cardiac surgery patients with preoperative anemia. We searched CENTRAL, MEDLINE and EMBASE for randomized controlled trials (RCTs) and observational studies comparing IV iron therapy to erythropoietin and/or oral iron or no therapy. We performed title and abstract, full-text screening, data extraction, and risk of bias assessment independently and in duplicate. We pooled data using a random effects model in RevMan5.3, and evaluated the risk of bias for RCTs and observational studies using the Cochrane and CLARITY tools, respectively. We evaluated the overall quality of evidence with the GRADE framework. We identified seven observational studies (n = 962) and four RCTs (n = 767) meeting eligibility criteria. Pooled data from observational studies demonstrated significant results in favour of IV iron therapy compared to no therapy for all-cause mortality (relative risk (RR) 0.41, 95% CI [0.25 to 0.67], p=0.0005, I2=0%, very low quality), units transfused per patient (MD -1.22, 95% CI [-1.85 to -0.60], p=0.0001, I2=0%, very low quality), renal failure (RR 0.50, 95% CI [0.36 to 0.69], p < 0.0001, I2=0%, very low quality), and hospital length of stay (mean difference (MD) 4.24, 95% CI [-6.86 to -1.63], p=0.001, I2=0%, very low quality). Pooled data from RCTs comparing IV iron therapy to oral iron therapy or no therapy demonstrated significant results in favour of IV iron therapy for reducing the number of patients transfused (RR 0.81, 95% CI [0.70 to 0.94], p=0.04 I2 = 26%, moderate quality). The pooled results for hospital length of stay, units transfused per patient, and renal failure from RCTs were consistent in direction with the observational studies, but did not reach statistical significance. The current body of evidence suggests that IV iron therapy may improve postoperative mortality and morbidity in adult cardiac surgery patients with preoperative anemia. However, these findings are based on moderate quality of evidence. The results support the need for a definitive randomized trial of IV iron in this population.