• Chintan V Dave, Gary M Brittenham, Jeffrey L Carson, and Soko Setoguchi.
• Center for Pharmacoepidemiology and Treatment Science, Institute for Health, Health Care Policy and Aging Research, Rutgers University, New Brunswick, Department of Pharmacy Practice and Administration, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, and Department of Veterans Affairs New Jersey Health Care System, East Orange, New Jersey (C.V.D.).
• Ann. Intern. Med. 2022 May 1; 175 (5): 656664656-664.

BackgroundThe risks for anaphylaxis among intravenous (IV) iron products currently in use have not been assessed.ObjectiveTo compare risks for anaphylaxis among 5 IV iron products that are used frequently.DesignRetrospective cohort study using a target trial emulation framework.SettingMedicare fee-for-service data with Part D coverage between July 2013 and December 2018.ParticipantsOlder adults receiving their first administration of IV iron.MeasurementsThe primary outcome was the occurrence of anaphylaxis within 1 day of IV iron administration, ascertained using a validated case definition. Analysis was adjusted for 40 baseline covariates using inverse probability of treatment weighting. The adjusted incidence rates (IRs) for anaphylaxis per 10 000 first administrations and odds ratios (ORs) were computed.ResultsThe adjusted IRs for anaphylaxis per 10 000 first administrations were 9.8 cases (95% CI, 6.2 to 15.3 cases) for iron dextran, 4.0 cases (CI, 2.5 to 6.6 cases) for ferumoxytol, 1.5 cases (CI, 0.3 to 6.6 cases) for ferric gluconate, 1.2 cases (CI, 0.6 to 2.5 cases) for iron sucrose, and 0.8 cases (CI, 0.3 to 2.6 cases) for ferric carboxymaltose. Using iron sucrose as the referent category, the adjusted ORs for anaphylaxis were 8.3 (CI, 3.5 to 19.8) for iron dextran and 3.4 (CI, 1.4 to 8.3) for ferumoxytol. When cohort entry was restricted to the period after withdrawal of high-molecular-weight iron dextran from the U.S. market in 2014, the risk for anaphylaxis associated with low-molecular-weight iron dextran (OR, 8.4 [CI, 2.8 to 24.7]) did not change appreciably. Anaphylactic reactions requiring hospitalizations were observed only among patients using iron dextran or ferumoxytol.LimitationGeneralizability to non-Medicare populations.ConclusionThe rates of anaphylaxis were very low with all IV iron products but were 3- to 8-fold greater for iron dextran and ferumoxytol than for iron sucrose.Primary Funding SourceNone.

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