The purpose of the trial is to evaluate and compare the effect of iron isomaltoside 1000 to iron sucrose in its ability to increase haemoglobin (Hb) in subjects with IDA when oral iron preparations are ineffective or cannot be used or where there is a clinical need to deliver iron rapidly.

IDA is highly prevalent in subjects with gastrointestinal diseases and cancer, menstruating or pregnant women, and subjects who have undergone bariatric procedure. IDA can have a substantial medical and quality of life (QoL) burden on the subjects and the treatment of these subjects includes controlling the bleeding and replenishing lost iron. Oral iron administration is often used in the clinical practice at many clinics; however, oral iron may not be tolerated by all subjects. Hence, there is a need for an alternative iron treatment in subjects, who do not tolerate oral iron.

This study is planned to compare the efficacy and safety of iron isomaltoside 1000 with another parenteral iron preparation (iron sucrose) in subjects with IDA and who are intolerant or unresponsive to oral iron therapy or who need iron rapidly.

Inclusion Criteria:

1. Men or women > 18 years having IDA caused by different aetiologies such as abnormal uterine bleeding, gastrointestinal diseases, cancer, bariatric procedures (gastric bypass operations), and other conditions leading to significant blood loss and with a documented history of intolerance or unresponsiveness to oral iron therapy for at least one month prior to study enrollment or where there at investigators judgment is a clinical need to deliver iron rapidly
2. Hb < 11 g/dL
3. TSAT < 20 %
4. S-ferritin < 100 ng/mL
5. Willingness to participate and signing the informed consent form

Exclusion Criteria:

1. Anaemia predominantly caused by factors other than IDA (e.g. anaemia with untreated vitamin B12 or folate deficiency, haemolytic anaemia)
2. Iron overload or disturbances in utilisation of iron (e.g. haemochromatosis and haemosiderosis)
3. Decompensated liver cirrhosis or active hepatitis (ALAT > 3 times upper limit of normal)
4. Active acute or chronic infections (assessed by clinical judgement supplied with white blood cells (WBC) and C-reactive protein (CRP))
5. Body weight < 50 kg
6. Rheumatoid arthritis with symptoms or signs of active inflammation
7. Pregnant or nursing women. In order to avoid pregnancy, women have to be surgically sterile or use adequate contraception (e.g. intrauterine devices, hormonal contraceptives, or double barrier method) during the whole study period and after the study has ended for at least 5 times plasma biological half-life of the investigational medicinal product
8. History of multiple allergies
9. Known hypersensitivity to parenteral iron or any excipients in the investigational drug products
10. Erythropoietin treatment within 8 weeks prior to the screening visit
11. Other iron treatment or blood transfusion within 4 weeks prior to the screening visit
12. Planned elective surgery during the study
13. Participation in any other clinical study within 3 months prior to the screening
14. Any other medical condition that, in the opinion of Investigator, may cause the subject to be unsuitable for the completion of the study or place the subject at potential risk from being in the study, e.g. uncontrolled hypertension, unstable ischaemic heart disease, or uncontrolled diabetes mellitus

FAS (N = 491): The FAS consisted of all subjects who were randomised, received at least one dose of the trial drug, and had at least one post-baseline Hb assessment.

From screening until week 5

The nature of the event will be described in precise, standard medical terminology. If known, a specific diagnosis was stated. Furthermore the Investigator described an AE regarding seriousness, severity, relatedness, and outcome.

It is only the subjects that received treatment that is included in the safety analysis. Of the 342 enrolled subjects in the Monofer arm only 333 was treated. Of the 169 subjects enrolled in the Venofer arm 168 was treated.