Testing equivalence of two doses of intravenous iron to treat iron deficiency in pregnancy: A randomised controlled trial

Department of Anaesthesia, Northern Adelaide Local Health Network, Lyell McEwin Hospital, Vale, Elizabeth, SA, Australia. Discipline of Acute Care Medicine, Adelaide Medical School, The University of Adelaide, SA, Australia. Discipline of Psychiatry, Adelaide Medical School, The University of Adelaide, Adelaide, SA, Australia. Northern Adelaide Mental Health Services, Lyell McEwin Hospital, Vale, Elizabeth, SA. Robinson Research Institute. University of South Australia, Clinical and Health Sciences, Quality Use of Medicines Pharmacy Research Centre, SA, Australia. Department of Obstetrics and Gynaecology, Lyell McEwin Hospital, SA, Australia. Adelaide Medical School, The University of Adelaide, SA, Australia. Hunter Medical Research Institute, Newcastle, NSW.

BJOG: an international journal of obstetrics and gynaecology. 2022
PICO Summary

Population

Pregnant women with iron deficiency (n= 278).

Intervention

500 mg of intravenous ferric carboxymaltose (n= 152).

Comparison

1,000 mg of intravenous ferric carboxymaltose (n= 126).

Outcome

The two doses were not equivalent within a 5% margin at any timepoint. At 4 weeks post-infusion, 26/73 (36%) participants required a repeat infusion in the 500 mg group compared with 5/67 (8%) in the 1,000 mg group (difference in proportions, 0.283 95% confidence interval (0.177, 0.389)). Overall, participants in the 500 mg arm received twice the repeat infusion rate (0.81 (SD= 0.824 vs. 0.40 (SD= 0.69), rate ratio 2.05, 95% CI (1.45, 2.91)).
Abstract
OBJECTIVE To test equivalence of two doses of intravenous iron (ferric carboxymaltose) in pregnancy. DESIGN Parallel, two-arm equivalence randomised controlled trial with an equivalence margin of 5%. SETTING Single centre in Australia. POPULATION 278 pregnant women with iron deficiency. METHODS Participants received either 500 mg (n=152) or 1000mg (n=126) of intravenous ferric carboxymaltose in the second or third trimester. MAIN OUTCOME MEASURES The proportion of participants requiring additional intravenous iron (500mg) to achieve and maintain ferritin >30ug/L (diagnostic threshold for iron deficiency) at 4 weeks post-infusion, and at 6 weeks, and 3-, 6- and 12-months postpartum. Secondary endpoints included repeat infusion rate, iron status, birth, and safety outcomes. RESULTS The two doses were not equivalent within a 5% margin at any timepoint. At 4 weeks post infusion, 26/73 (36%) participants required a repeat infusion in the 500 mg group compared with 5/67 (8%) in the 1000 mg group (difference in proportions, 0.283 95% confidence interval (0.177, 0.389)). Overall, participants in the 500 mg arm received twice the repeat infusion rate (0.81 (SD= 0.824 vs 0.40 (SD= 0.69), rate ratio 2.05, 95% CI (1.45, 2.91)). CONCLUSIONS Administration of 1000 mg ferric carboxymaltose in pregnancy maintains iron stores and reduces the need for repeat infusions. A 500 mg dose requires ongoing monitoring to ensure adequate iron stores are reached and sustained.
Study details
Language : eng
Credits : Bibliographic data from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine