Correction to: Protocol and baseline data for a prospective open-label explorative randomized singlecenter comparative study to determine the effects of various intravenous iron preparations on markers of oxidative stress and kidney injury in chronic kidney disease (IRON-CKD).

After publication of our article [1], the database of IRON-CKD has undergone vigorous inspection - the authors have therefore re-examined database.

Protocol and baseline data for a prospective open-label explorative randomized single-center comparative study to determine the effects of various intravenous iron preparations on markers of oxidative stress and kidney injury in chronic kidney disease (IRON-CKD).

BACKGROUND: Intravenous (IV) iron is frequently used to treat iron deficiency/anemia in patients who are unable to tolerate oral iron or the oral iron is not sufficient toreplete iron requirements. However, safety concerns regarding the potential increase in oxidative stress and other adverse effects persist and it remains unclear whether all iron preparations are equivalent. Indeed, the comparative risk of adverse events with IV iron preparations has not been extensively assessed. We hypothesize that IV iron leads to changes in oxidative stress, endothelial function, and potential renal damage depending on the iron formulation (related to the generation of "free" or catalytic labile iron) and this may result in more tubular and glomerular injury manifested as increased proteinuria and raised neutrophil gelatinase-associated lipocalin (NGAL) levels in patients with chronic kidney disease (CKD). METHODS: IRON-CKD is a prospective, open-label, explorative, randomized, single-center study designed to compare the safety and efficacy of three parenteral iron preparations: low-molecular-weight iron dextran-Cosmofer, iron sucrose-Venofer, and iron isomaltoside-Monofer. The study includes 40 adults who have established CKD stages 3-5 and serum ferritin (SF) of less than 200 µg/L or transferrin saturation (TS) of less than 20% (or both); they were randomly assigned in a 1:1:1:1 ratio to 200 mg iron dextran, 200 mg iron sucrose, 200 mg iron isomaltoside, or 1000 mg iron isomaltoside. After randomization, participants undergo baseline assessments and then an iron infusion. Each participant is followed up at 2 h, day 1, week 1, and months 1 and 3. At each follow-up visit, patients undergo clinical review, measurement of pulse wave velocity (PWV), blood tests for renal function, and collection of serum/plasma samples for oxidative stress and inflammatory markers. The primary outcomes are measures of oxidative stress, inflammatory markers, and markers of acute renal injury in comparison with baseline measures of each iron preparation and between each of the iron preparations. Secondary objectives include effects on hematinic profiles and hemoglobin concentrations, changes in arterial stiffness, incidence of significant side effects, and change in patients' quality of life. RESULTS: Between October 2015 and April 2018, 521 individuals were identified as potential participants; 216 were contacted, 56 expressed an interest, 49 attended a screening visit, and 40 were confirmed to meet the eligibility criteria and were randomly assigned. The mean age was 58.8 (standard error of the mean 2.2) years, and 23 (58%) were male. All patients were white and English-speaking. The mean SF was 68.8 µg/L, TS was 21.4%, and haemoglobin was 122.6 g/L at randomization for the whole group. The mean estimated glomerular filtration rate was 28.2 mL/min/1.73 m2 the urinary protein/ creatinine ratio was 154.2 mg/mmol, and CRP was 7.5 mg/L. DISCUSSION: IRON-CKD will provide important information on the short-term effects of three preparations of IV iron in CKD patients with biochemical functional or absolute iron deficiency on measures of oxidative stress, inflammation, endothelial function, and renal injury. TRIAL REGISTRATION: European Clinical Trials Database (EudraCT) number 2010-020452-64 .