Frigstad SO [1,2] , Islam MM [1]

Affiliates

Department of medicine, Vestre Viken Bærum Hospital, Gjettum, Norway [1], Institute of clinical medicine, University of Oslo, Oslo, Norway [2]

Abstract

Background
In inflammatory bowel disease (IBD), iron deficiency anemia is the most common systemic complication, and has been reported in 20-42% of patients, while iron deficiency has been reported in 35-90% of patients. Intravenous iron allows for efficient and well-tolerated treatment in iron deficiency, and is routinely used in IBD. Infusion reactions are in clinical studies reported in 1-3 % of iron infusions. The pathogenesis of these infusion reactions is not fully known, but complement-activated pseudoallergy seems to be the most important mechanism. The aim of this study was to investigate the safety of iron isomaltoside in clinical practice.

Methods
We have performed a prospective registration of all infusion reactions and reports of delayed hypersensitivity following infusions of iron isomaltoside in our hospital from November 2012 – June 2018. The simplified dosing regimen was recommended, and 1000 mg was used as the defined daily dose in the data analyses. The study was performed as a quality assessement project and was approved by the Regional Data Protection Official. Clinical and epidemiological data were registered, as well as study drug characteristics, dosing, type of hypersensitivity and outcome variables. All hypersensitivity reactions were reported to the health authorities.

Results
We estimated that a total of 1240 infusions equivalent to 1000 mg of iron isomaltoside were given. Acute infusion reactions were reported in 2 % (29/1240) of infusions and delayed hypersensitivity in 0.5 % (6/1240) of infusions. More female (25/29) than male (4/29) patients had acute infusion reactions (p < 0.05). Three patients got infusion reactions on the second infusion and one patient had infusion reactions on both the second and the third infusion. We found no association between dose given and frequency of infusion reactions. No single batch of study drug associated with more infusion reactions was identified. All patients had uneventful recoveries.

Conclusions
In this study hypersensitivity following iron isomaltoside was relatively rare in clinical practice. Infusion reactions are most frequently mild and seem to occur more often in women. No association to dose given was shown.