Evaluating Iron Sucrose Discordance: A Retrospective Health System Review

Background

Anemia affects approximately 9% of the US population, and iron deficiency has been identified as the primary cause.^1,2 Intravenous (IV) iron is more efficacious and rapid in correcting iron deficiency anemia than oral supplementation but requires more involvement from the health system to minimize discordance, which is defined as an inappropriate dose or timing of administration based on institutional policies.² Social drivers of health (SDOH) likely play a role in IV iron discordance and can be quantified through a social vulnerability index (SVI). Although there are a variety of SVIs, each is a novel composite measure encompassing variables that correspond to key SDOH; however, the use of an SVI to quantify SDOH in the setting of iron discordance has not been studied.^3,4 The dosing schedule of IV iron also likely contributes to discordance. Older-generation IV iron products, including iron sucrose, iron dextran, and sodium ferric gluconate, require more frequent dosing and have a higher incidence of discordance, yet they remain widely used due to payer coverage and lower per-dose cost.⁴

Iron sucrose, an older-generation IV iron product, is Cone Health’s preferred IV iron product. Therefore, it is essential for the health system to optimize its use. In response to the nationwide fluid shortage in the fall of 2024, Cone Health outpatient infusion centers transitioned the administration of iron sucrose 200-mg doses from an IV piggyback (IVPB) infusion to an IV push because doses of up to 200 mg can be given as an IV push.⁵ Providers were encouraged to increase the prescribing of treatment courses in increments of 200 mg when appropriate to help conserve fluids. Because faster infusion rates with IV iron are a risk factor for infusion reactions, there was concern that this transition to IV push would increase the incidence of infusion reactions.

Limited data exist on the incidence of infusion reactions with iron sucrose IVPB infusion vs IV push, but data from a prior study evaluating the safety of iron sucrose 200-mg IV pushes showed that 97.5% of doses were administered without an adverse event.⁶ The purpose of this study was to evaluate the impact of transitioning iron sucrose 200-mg doses to IV push on iron sucrose discordance.

Objectives

The study’s primary objective was to evaluate the incidence of iron sucrose discordance in the pre- and post-IV push groups. Discordance was defined as not receiving at least 1 g of iron sucrose within a 14-day period. The secondary objectives compared in the pre- and post-IV push groups were to determine the reasons for discordance and the incidence of infusion reactions. An additional secondary objective, compared across the concordant and discordant treatment courses, was to determine CDC and Agency for Toxic Substances and Disease Registry SVI rankings.⁷

Methods

This was an institutional review board–reviewed, determined-exempt, multicenter, retrospective, pre-post study that evaluated iron sucrose discordance over 3-month periods in the pre- and post-IV push groups. For the pre-IV push group, the study period was March 1, 2024, through May 31, 2024. For the post-IV push group, the study period was October 21, 2024, through January 21, 2025. All iron sucrose doses, including those greater than 200 mg, were included in the analysis because the transition to 200 mg as an IV push was a major practice change for the health system; therefore, including all doses enabled assessment of the full impact of the transition.

Setting

The study evaluated iron sucrose administration across 10 Cone Health outpatient infusion centers: 5 standalone centers and 5 embedded within cancer centers.

Patients

Patients 18 years or older who received their prescribed iron sucrose treatment course at a Cone Health infusion center during their respective study period were included. Patients were excluded if no SVI data were available.

Data Sources

Patient data, including patient demographics, addresses, and administered iron sucrose treatment courses, were generated from an electronic medical record (EMR) report. Data collection primarily used the EMR report, with chart review as needed for clarification. A report from Cone Health’s safety and event reporting portal was used to identify the incidence of infusion reactions in the patient population generated from the EMR report. To collect SVI data, Federal Information Processing Standards (FIPS) codes for socioeconomic status, household characteristics, racial and ethnic minority status, housing type, and transportation, and overall SVI ranking were obtained via geocoding. FIPS codes were then used to obtain SVI rankings via 2020 North Carolina Census data reported by the CDC. SVI rankings are tract rankings based on percentiles ranging from 0 to 1, with higher values indicating greater vulnerability to SDOH.

Statistical Methods

A combination of Student t-test, Pearson chi-square test, and Fisher exact test was used to analyze data with statistical software Stata 15.1.

Results

Descriptive Data

There were 613 treatment courses included in the pre-IV push group and 543 treatment courses included in the post-IV push group. Baseline characteristics were similar between the groups (Table 1). The mean age of patients was approximately 57 years; 77% of patients were female, over 50% were White, and 4% were Hispanic or Latino. The primary payer in this study was commercial insurance. Regarding iron sucrose administration, approximately 80% of treatment courses were administered at a cancer center, and 200 mg was the most frequently prescribed dose. There was an 11.5% increase in iron sucrose 200 mg administered after the IV push.

Outcome Data

For the primary objective, 545 (88.9%) treatment courses in the pre-IV push group were discordant compared with 471 (87.7%) in the post-IV push group (P =.26). Distribution of reasons for discordance differed between groups (P =.001), although receiving a dose of less than 1 g was the primary reason for discordance in both groups (68.4% in the pre-IV push group, 57.3% in the post-IV push group). Discordance due to a prolonged duration of more than 14 days increased from the pre-IV push to the post-IV push group (15.4% and 19.5%, respectively). Discordance due to receiving less than 1 g over a prolonged period of more than 14 days also increased from the pre-IV push group to the post-IV push group (16.1% and 23.1%, respectively). The incidence of discordance due to prescribing, such as prescribing a 300-mg treatment course for 3 doses, was not collected. The incidence of infusion reactions was 0.3% in the pre-IV push group and 0.35% in the post-IV push group (P = .81). There was no clear trend or statistical significance in SVI rankings (Table 2⁷).

Discussion

The transition of iron sucrose 200-mg doses from IVPB infusion to IV push in the setting of the nationwide fluid shortage resulted in approximately a 12% increase in 200-mg doses administered but did not result in a statistical difference in the incidence of discordance. This was a positive result, as it was suspected that the incidence of discordance would increase due to increased visits needed to complete a treatment course.

The transition also resulted in an increase in treatment courses with discordance, driven by prolonged duration (> 14 days), and a decrease in patients with discordance, driven by insufficient dose (< 1 g). In other words, more patients were receiving a sufficient dose, but the time to complete the full course was prolonged, likely due to the need for more visits. Reasons for patients receiving less than 1 g and/or for doses being delayed or not received over a prolonged period (> 14 days) were not explored due to inconsistent chart documentation.

Regarding the safety of 200-mg doses administered as an IV push, no difference in the incidence of infusion reactions was observed compared with the IVPB infusion. Nurses and pharmacists were encouraged to improve reporting of infusion reactions per protocol around the time of the transition to 200 mg as an IV push; therefore, the observed incidence of infusion reactions for the IV push is likely a conservative estimate due to possible overreporting.

No clear relationship was identified between SVI rankings and discordance in iron sucrose. A statistically significant difference in SVI rankings by racial and ethnic minority status was observed in the post-IV push group, but its validity is unclear, as it was not replicated in the pre-IV push group. This is the first known study to use SVI rankings to represent SDOH in the setting of IV iron discordance; therefore, it is possible that SVI rankings are not validated in this setting.

Limitations

A key limitation of this study is that although treatment courses prescribed at less than 1 g were administered as prescribed, they were considered discordant per the current study’s definition. Another limitation is that the high discordance rate limited the statistical analysis of concordant data for SVI rankings, as there were only approximately 70 concordant treatment courses per group. Lastly, the definition of discordance varies among institutions. Previous studies have used discordant durations of 4 to 6 weeks; therefore, this may limit the generalizability of some aspects of this study.

Conclusion

The primary takeaway from this study is the utility of iron sucrose 200 mg as an IV push dose, given its similar incidence of discordance and infusion reactions compared with IVPB. It is important to highlight that a major advantage of using the IV push dose over IVPB is the time saved for the pharmacy technician, as there is no need to compound the product in the IV room.

Other benefits of using the IV push dose include cost savings from no longer needing normal saline bags and tubing for dose preparation, nurse time saved from administering the dose over 5 minutes instead of 15 minutes, and the ability to save the normal saline bags for products that cannot be given as an IV push. As a result of this study and the ability to reduce the workload in IV rooms and infusion pharmacies, Cone Health anticipates continuing to use 200-mg doses as IV pushes even after the fluid shortage resolves.

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