Ferric Derisomaltose Versus Iron Sucrose in Pregnancy (FLIP): A Retrospective Observational Study on Outpatient Intravenous Iron Infusion Capacity

Introduction: Iron deficiency anemia (IDA) is a widespread condition in pregnancy and is associated with preterm delivery, low birth weight, and impaired cognitive development. Adequate oral iron repletion is challenging in pregnancy due to increased iron demands and vulnerability to gastrointestinal upset. Individuals with intolerance or inadequate response to oral iron, severe IDA, or less than 4 weeks to delivery are managed with intravenous (IV) iron during the 2nd and 3rd trimesters. At our academic center, the treatment of pregnant patients with IV iron is limited by infusion clinic capacity. Most pregnant patients require 900-1000 mg of IV elemental iron. Administering this dose requires three infusions of iron sucrose (IS) or a single infusion of ferric derisomaltose (FDI). We hypothesized that the use of FDI would increase capacity to administer IV iron to pregnant patients compared to IS.

Methods: Our center is a high-risk obstetrical and academic teaching hospital performing approximately 4,500 deliveries annually. In June 2022, FDI was added to IS as an IV iron treatment option for IDA in pregnancy, with its formal implementation adopted in August 2023. According to institutional policy, IS is given as 300 mg over 2 hours and FDI as 500 mg over 30 minutes or 1000 mg over 1 hour. Fetal monitoring is not routinely performed during infusions.

This retrospective observational study compared all pregnant patients 18 years and older treated with at least one dose of IV iron (IS or FDI) at our obstetrics infusion clinic between June 2021 and February 2024. Patients with incomplete records were excluded. The primary outcome was the total number of unique patients treated with outpatient IV iron (IS or FDI) per month in the obstetrics infusion clinic during baseline Period 1 (June 2021 to May 2022), Period 2 when FDI was available (June 2022 to July 2023), and Period 3 when the formal policy was implemented (August 2023 to February 2024). Secondary outcomes compared IS vs. FDI for the following metrics: infusion time per visit, mean number of visits per patient per pregnancy, total infusion time per patient per pregnancy, total dose of IV iron infused prior to delivery, treatment completion rate (all infusions ordered were infused; yes vs. no), and adverse reactions.

Patients were identified using OBTV, the hospital database for pregnant patients, and assessed for eligibility. Patient charts were reviewed for demographics and laboratory data, and nursing records for infusion details. For patients without an assigned procedure duration, 60/30 minutes was assumed for 1000 mg/500 mg FDI and 120 minutes for 300 mg IS as per the institutional policy. This study was approved by the institutional research ethics board. Descriptive analyses were summarized by mean and standard deviation. A P value of < 0.05 was considered statistically significant.

Results: During the study period, 327 patients received IS and 187 patients received FDI. The implementation of FDI increased the mean number (±SD) of patients treated per month with IV iron from 20.1±4.5 in Period 1 to 20.9±4.4 in Period 2 to 30.7±6.3 in Period 3 (p<0.0001: Period 1&2 vs. Period 3). Compared to IS, FDI reduced the mean IV iron infusion time per visit (113±9 vs. 65±10 minutes; p<0.0001), the mean number of visits per patient (2.2±0.8 vs. 1.0±0.1; p<0.0001), and the mean total IV iron infusion time per patient per pregnancy (252±92 vs. 65±10 minutes; p<0.0001). The mean total dose of IV iron infused prior to delivery was 679±246 mg for IS vs. 987±81 mg for FDI (p<0.0001). The course completion rate was 83% for IS and 99% for FDI (p<0.0001). Adverse reactions occurred in 42 (13.0%) patients who received IS and 10 patients (5.4%) who received FDI; most were mild, with only one patient treated with IS being sent to triage for further assessment.

Conclusion: Using FDI in pregnancy enhanced the capacity and efficiency of the IV iron infusion clinic by treating more patients per month, reducing infusion times, and limiting the number of visits required. This initiative improves the quality of care by optimizing maternal and fetal health outcomes associated with correcting iron deficiency anemia and reducing the burden of multiple visits that disproportionately affect those of low socioeconomic status.