LAUSR

Background Intravenous iron is often used to treat iron deficiency anaemia in non-dialysis chronic kidney disease (ND-CKD), but the optimal dosing regimen remains unclear. We evaluated the impact of high- versus low-dose intravenous iron isomaltoside on the probability of retreatment with intravenous iron in iron-deficient ND-CKD patients. Methods This real-world, prospective, observational study collected data from 256 ND-CKD patients treated for anaemia in the UK. Following an initial course of iron isomaltoside, patients were followed for ≥12 months. Iron dose and the need for retreatment were determined at the investigators’ discretion. The primary study outcome was the need for retreatment at 52 weeks compared between patients who received >1000 mg of iron during Course 1 and those who received ≤1000 mg. Safety was evaluated through adverse drug reactions. Results The probability of retreatment at Week 52 was significantly lower in the >1000 mg iron group ( n  = 58) versus the ≤1000 mg group ( n  = 198); hazard ratio (95% confidence interval [CI]): 0.46 (0.20, 0.91); p  = 0.012. Mean (95% CI) haemoglobin increased by 6.58 (4.94, 8.21) g/L in the ≤1000 mg group and by 10.59 (7.52, 13.66) g/L in the >1000 mg group ( p  = 0.024). Changes in other blood and iron parameters were not significantly different between the two groups. Administering >1000 mg of iron isomaltoside saved 8.6 appointments per 100 patients compared to ≤1000 mg. No serious adverse drug reactions were reported. Of the patients who received ≤1000 mg of iron in this study, 82.3% were eligible for a dose >1000 mg. Conclusions The >1000 mg iron isomaltoside regimen reduced the probability of retreatment, achieved a greater haemoglobin response irrespective of erythropoiesis-stimulating agent treatment, and reduced the total number of appointments required, compared to the ≤1000 mg regimen. Many of the patients who received ≤1000 mg of iron were eligible for >1000 mg, indicating that there was considerable underdosing in this study. Trial registration ClinicalTrials.gov NCT02546154 , 10 September 2015.