Optimizing Preoperative Iron Deficiency Anemia in Patients Undergoing Cardiac Surgery

Abstract

Background: Preoperative anemia is common in patients undergoing cardiac surgery, with iron deficiency being the most common cause of anemia in these patients. Patients who are anemic in the preoperative setting have worse perioperative outcomes than patients with normal hemoglobin levels including higher rates of red cell transfusions, acute kidney injury, increased length of stay, and increased mortality. At the University of Virginia (UVA) Medical Center, there was no institutional process in place to identify and treat iron deficiency anemia in patients planned to undergo cardiac surgery. Objective: The UVA Perioperative Blood Management Committee is a newly-formed multidisciplinary group consisting of members from the departments of Hematology, Anesthesiology, Thoracic and Cardiovascular Surgery, Perfusion, and Blood Bank who work together to improve perioperative patient outcomes and blood product utilization. We set out to implement a testing algorithm with the purpose of improving the proportion of anemic patients undergoing cardiac surgery who have iron studies performed in the outpatient setting, thereby improving the percentage of patients receiving intravenous (IV) iron preoperatively. Methods: We adapted two published perioperative treatment algorithms (Lin, Hematology Am Soc Hematol Educ Program 2019; Munting and Klein, Anaesthesia 2019) which recommend iron therapy in patients with hemoglobin < 13 g/dL, ferritin < 100 µg/L, and/or transferrin saturation < 20% for our cardiac surgery preoperative clinic. In November 2022, we implemented a reflex test within Epic electronic medical record that automatically sent ferritin, iron, and transferrin for patients with hemoglobin < 13 g/dL to evaluate for iron deficiency. Patients meeting parameters for iron deficiency (ferritin < 30 ng/mL and/or transferrin saturation < 20%) were then scheduled for iron infusions. We compared the percentage of patients undergoing testing for iron deficiency, as well as the percentage of anemic patients receiving iron infusion preoperatively, to those from a six month period prior to our start date. Results: Between May 31, 2022 and October 31, 2022, 19% of cardiac surgery patients at UVA with hemoglobin values < 13 g/dL had iron studies drawn in the three months prior to surgery. After implementing outpatient reflex iron testing, that number increased to 42% between November 2022 and May 2023 (p < 0.001). In the six months prior to implementation, four iron deficient cardiac surgery patients received preoperative IV iron an average of one day prior to surgery. Between November 1, 2022 and May 29, 2023, fifteen patients received IV iron an average of 5.7 days prior to surgery. The patients who received IV iron had lower rates of blood transfusions than anemic patients who did not receive IV iron (53% vs. 65%) and fewer units of blood transfused per patient who received blood (3.1 vs. 5.7). Conclusions: Results from the first seven months of this project suggest that using a standardized testing methodology in the outpatient setting can increase the uptake of iron testing and thereby treatment of iron deficiency anemia in the preoperative setting. Patients who received IV iron had lower rates of blood transfusions and received fewer units of blood on average than anemic patients who did not receive IV iron. We next plan to implement an iron testing strategy in cardiac surgery inpatients to further improve rates of iron testing and iron infusions in this population. We have created an IRB-approved database to study more patient-centered outcomes such as acute kidney injury, stroke, length of stay, readmissions, and mortality to determine if we can detect a measurable impact from IV iron administration in our patient population.