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Predicting response to iron supplementation in patients with active inflammatory bowel disease (PRIme): a randomised trial protocol
Loveikyte, R., Duijvestein, M., Mujagic, Z., Goetgebuer, R. L., Dijkstra, G., van der Meulen-de Jong, A. E.
BMJ open. 2024;14(1):e077511
Abstract
INTRODUCTION Iron deficiency anaemia (IDA) is the most common systemic manifestation of inflammatory bowel disease (IBD) that has detrimental effects on quality of life (QoL) and disease outcomes. Iron deficiency (ID), with or without anaemia, poses a diagnostic and therapeutic challenge in patients with IBD due to the multifactorial nature of ID(A) and its frequent recurrence. Elevated hepcidin-a systemic iron regulator that modulates systemic iron availability and intestinal iron absorption-has been associated with oral iron malabsorption in IBD. Therefore, hepcidin could assist in therapeutic decision-making. In this study, we investigate whether hepcidin can predict response to oral and intravenous iron supplementation in patients with active IBD undergoing anti-inflammatory treatment. METHODS AND ANALYSIS PRIme is an exploratory, multicentre, open-label and randomised trial. All adult patients with active IBD and ID(A) will be assessed for eligibility. The participants (n=90) will be recruited at five academic hospitals within the Netherlands and randomised into three groups (1:1:1): oral ferrous fumarate, oral ferric maltol or intravenous iron. Clinical and biochemical data will be collected at the baseline and after 6, 14 and 24 weeks. Blood samples will be collected to measure hepcidin and other biomarkers related to iron status. In addition, patient-reported outcomes regarding QoL and disease burden will be evaluated. The primary outcome is the utility of hepcidin as a predictive biomarker for response to iron therapy, which will be assessed using receiver operating curve analysis. ETHICS AND DISSEMINATION The study has been approved by the Institutional Review Board at the Leiden University Medical Center (IRB No. P21.109) and other study sites. All participants will provide written informed consent to enrol in the study. The findings will be published in a peer-reviewed journal and disseminated at scientific conferences; the dataset will be available on reasonable request. TRIAL REGISTRATION Prospectively registered in the https://clinicaltrials.gov/ and the Eudra registries. First submitted on 10 May 2022 to the ClinicalTrials.gov (ID: NCT05456932) and on 3 March 2022 to the European Union Drug Regulating Authorities Clinical Trials Database (ID: 2022-000894-16).
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Intravenous ferric carboxymaltose versus oral ferrous sulfate replacement in elderly patients after acute non-variceal gastrointestinal bleeding (FIERCE): protocol of a multicentre, open-label, randomised controlled trial
Teutsch, B., Váncsa, S., Farkas, N., Szakács, Z., Vörhendi, N., Boros, E., Szabó, I., Hágendorn, R., Alizadeh, H., Hegyi, P., et al
BMJ open. 2023;13(3):e063554
Abstract
INTRODUCTION Acute gastrointestinal bleeding (GIB) is a life-threatening emergency with a critical economic burden. As a result of bleeding, anaemia often requires intravenous or oral iron supplementation. Elderly patients are even more prone to untoward outcomes after hospital discharge if iron supplementation is inefficient. There is a gap in current guidelines on which supplementation route clinicians should choose. We aim to investigate the effect of one dose of intravenous iron therapy versus 3-month oral iron administration on anaemia in an elderly population. METHODS AND ANALYSIS The FIERCE study is an open-label, randomised controlled, two-armed trial. At least 48 hours after the acute non-variceal GIB treatment, patients will be recruited in participating centres. A random sequence generator will allocate the participants to group A (intravenous ferric carboxymaltose, 1000 mg) or group B (oral ferrous sulfate (FS), ca. 200 mg every day) with an allocation ratio of 1:1 on the day of the planned discharge from the hospital. Randomisation will be stratified for participating centres and the need for transfusion within the same hospitalisation before recruitment to the trial. Quality of life assessment, functional measurement and laboratory tests will be performed at baseline, 1 and 3 months±7 days after enrolment to the trial. The primary endpoint is a composite endpoint, including all-cause mortality, anaemia-associated unplanned emergency visit and anaemia-associated unplanned hospital admission within 3 months of enrolment in the trial. ETHICS AND DISSEMINATION The study has been approved by the relevant organisation, the Scientific and Research Ethics Committee of the Hungarian Medical Research Council (46395-5/2021/EÜIG). We will disseminate our results to the medical community and will publish our results in peer-reviewed journals. TRIAL REGISTRATION The trial has been registered at ClinicalTrials.gov (NCT05060731).
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Role of Oral Iron Supplementation for Anemia Secondary to Acute Nonvariceal Upper Gastrointestinal Bleeding: A Randomized Controlled Trial
Chang A, Rugivarodum M, Pungpipattrakul N, Akarapatima K, Suwanno K, Rattanasupar A, Ovartlarnporn B, Prachayakul V
Journal of gastroenterology and hepatology. 2023
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Editor's Choice
Abstract
BACKGROUND AND AIM Although acute upper gastrointestinal bleeding (UGIB) can lead to anemia, evidence regarding the effects of oral iron supplementation on UGIB-induced anemia following discharge remains lacking. The present study aimed to investigate the effects of oral iron supplementation on hemoglobin response and iron storage in patients with anemia secondary to nonvariceal UGIB. METHODS This randomized controlled trial included 151 patients with nonvariceal UGIB who had anemia at discharge. Patients were assigned to a 1:1 block in which they were either administered 6 weeks of 600 mg/d oral ferrous fumarate (treatment group, n=77) or treated without iron supplementation (control group, n=74). The primary outcome was composite hemoglobin response (hemoglobin elevation greater than 2 g/dL or no anemia at the end of treatment [EOT]). RESULTS The proportion of patients achieving composite hemoglobin response was greater in the treatment group than in the control group (72.7% vs. 45.9%; adjusted risk ratio [RR], 2.980; p=0.004). At EOT, the percentage change in the hemoglobin level (34.2 ± 24.8 % vs. 19.4 ± 19.9 %; adjusted coefficient, 11.543; p<0.001) was significantly higher in the treatment group than in the control group; however, the proportions of patients with a serum ferritin level <30 μg/L and a transferrin saturation <16% were lower in the treatment group (all p<0.05). No significant differences in treatment-associated adverse effects and adherence rates were observed between the groups. CONCLUSIONS Oral iron supplementation exerts beneficial effects on anemia and iron storage following nonvariceal UGIB without significantly impacting rates of adverse effects or adherence. CLINICAL TRIAL REGISTRATION TCTR20190225002.
PICO Summary
Population
Patients with anaemia secondary to nonvariceal upper gastrointestinal bleeding (n= 151).
Intervention
Six weeks of 600 mg/d oral ferrous fumarate (treatment group, n= 77).
Comparison
No iron supplementation (control group, n= 74).
Outcome
The proportion of patients achieving composite haemoglobin response was greater in the treatment group than in the control group (72.7% vs. 45.9%; adjusted risk ratio [RR], 2.980). At end of treatment, the percentage change in the haemoglobin level (34.2 ± 24.8 % vs. 19.4 ± 19.9 %; adjusted coefficient, 11.543) was significantly higher in the treatment group than in the control group; however, the proportions of patients with a serum ferritin level <30 μg/L and a transferrin saturation <16% were lower in the treatment group. No significant differences in treatment-associated adverse effects and adherence rates were observed between the groups.
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Ferric carboxymaltose versus ferrous fumarate in anemic children with inflammatory bowel disease: the POPEYE randomized controlled clinical trial
Bevers N, Van de Vijver E, Aliu A, Ardabili AR, Rosias P, Stapelbroek J, Maartens IAB, van de Feen C, Escher JC, Oudshoorn A, et al
The Journal of pediatrics. 2022
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Editor's Choice
Abstract
OBJECTIVE To determine whether intravenous (IV) or oral iron suppletion is superior in improving physical fitness in anemic children with inflammatory bowel disease (IBD). STUDY DESIGN We conducted a clinical trial at 11 centers. Children aged 8 to 18 with IBD and anemia (defined as hemoglobin (Hb) z-score < -2) were randomly assigned to a single IV dose of ferric carboxymaltose or 12 weeks of oral ferrous fumarate. Primary endpoint was the change in 6-minute walking distance (6MWD) from baseline, expressed as z-score. Secondary outcome was a change in Hb z-score from baseline. RESULTS We randomized 64 patients (33 IV iron; 31 oral iron) and followed them for 6 months. One month after the start of iron therapy, the 6MWD z-score of patients in the IV group had increased by 0.71 compared with -0.11 in the oral group (P=0.01). At 3- and 6-months follow-up, no significant differences in 6MWD z-scores were observed. Hb z-scores gradually increased in both groups and the rate of increase was not different between groups at 1, 3 and 6 months after initiation of iron therapy (overall P=0.97). CONCLUSION In this trial involving anemic children with IBD, a single dose of IV ferric carboxymaltose was superior to oral ferrous fumarate with respect to quick improvement of physical fitness. At 3 and 6 months after initiation of therapy, no differences were discovered between oral or IV therapy. The increase of Hb over time was comparable in both treatment groups. TRIAL REGISTRATION NTR4487 [Netherlands Trial Registry].
PICO Summary
Population
Children with anaemia and inflammatory bowel disease, enrolled in the POPEYE trial, in 9 Dutch and 2 Belgian hospitals (n= 64).
Intervention
Single intravenous dose of ferric carboxymaltose (IV group), (n= 33).
Comparison
12 weeks of oral ferrous fumarate (oral group), (n= 31).
Outcome
The primary endpoint was the change in 6-minute walking distance (6MWD) from baseline, expressed as z-score. The secondary outcome was a change in Hb z-score from baseline. One month after the start of iron therapy, the 6MWD z-score of patients in the IV group had increased by 0.71 compared with -0.11 in the oral group. At 3- and 6- months follow-up, no significant differences in 6MWD z-scores were observed. Hb z-scores gradually increased in both groups and the rate of increase was not different between groups at 1, 3 and 6 months after initiation of iron therapy.
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Hypophosphataemia following ferric derisomaltose and ferric carboxymaltose in patients with iron deficiency anaemia due to inflammatory bowel disease (PHOSPHARE-IBD): a randomised clinical trial
Zoller H, Wolf M, Blumenstein I, Primas C, Lindgren S, Thomsen LL, Reinisch W, Iqbal T
Gut. 2022
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Editor's Choice
Abstract
OBJECTIVE Intravenous iron-a common treatment for anaemia and iron deficiency due to inflammatory bowel disease (IBD)-can cause hypophosphataemia. This trial compared the incidence of hypophosphataemia after treatment with ferric carboxymaltose (FCM) or ferric derisomaltose (FDI). DESIGN This randomised, double-blind, clinical trial was conducted at 20 outpatient hospital clinics in Europe (Austria, Denmark, Germany, Sweden, UK). Adults with IBD and iron deficiency anaemia (IDA) were randomised 1:1 to receive FCM or FDI at baseline and at Day 35 using identical haemoglobin- and weight-based dosing regimens. The primary outcome was the incidence of hypophosphataemia (serum phosphate <2.0 mg/dL) at any time from baseline to Day 35 in the safety analysis set (all patients who received ≥1 dose of study drug). Markers of mineral and bone homeostasis, and patient-reported fatigue scores, were measured. RESULTS A total of 156 patients were screened; 97 (49 FDI, 48 FCM) were included and treated. Incident hypophosphataemia occurred in 8.3% (4/48) FDI-treated patients and in 51.0% (25/49) FCM-treated patients (adjusted risk difference: -42.8% (95% CI -57.1% to -24.6%) p<0.0001). Both iron formulations corrected IDA. Patient-reported fatigue scores improved in both groups, but more slowly and to a lesser extent with FCM than FDI; slower improvement in fatigue was associated with greater decrease in phosphate concentration. CONCLUSION Despite comparably effective treatment of IDA, FCM caused a significantly higher rate of hypophosphataemia than FDI. Further studies are needed to address the longer-term clinical consequences of hypophosphataemia and to investigate mechanisms underpinning the differential effects of FCM and FDI on patient-reported fatigue.
PICO Summary
Population
Adults with inflammatory bowel disease and iron deficiency anaemia enrolled in the PHOSPHARE-IBD trial in five European countries (n= 97).
Intervention
Ferric carboxymaltose (FCM), (n= 48).
Comparison
Ferric derisomaltose (FDI), (n= 49).
Outcome
Incident hypophosphataemia occurred in 8.3% FDI-treated patients and in 51% FCM-treated patients (adjusted risk difference: -42.8% (95% CI -57.1% to -24.6%)). Both iron formulations corrected iron deficiency anaemia. Patient-reported fatigue scores improved in both groups, but more slowly and to a lesser extent with FCM than FDI; slower improvement in fatigue was associated with greater decrease in phosphate concentration.
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Interventions for treating iron deficiency anaemia in inflammatory bowel disease
Gordon M, Sinopoulou V, Iheozor-Ejiofor Z, Iqbal T, Allen P, Hoque S, Engineer J, Akobeng AK
The Cochrane database of systematic reviews. 2021;1:Cd013529
Abstract
BACKGROUND Inflammatory bowel disease affects approximately seven million people globally. Iron deficiency anaemia can occur as a common systemic manifestation, with a prevalence of up to 90%, which can significantly affect quality of life, both during periods of active disease or in remission. It is important that iron deficiency anaemia is treated effectively and not be assumed to be a normal finding of inflammatory bowel disease. The various routes of iron administration, doses and preparations present varying advantages and disadvantages, and a significant proportion of people experience adverse effects with current therapies. Currently, no consensus has been reached amongst physicians as to which treatment path is most beneficial. OBJECTIVES The primary objective was to evaluate the efficacy and safety of the interventions for the treatment of iron deficiency anaemia in people with inflammatory bowel disease. SEARCH METHODS We searched CENTRAL, MEDLINE, Embase, and two other databases on 21st November 2019. We also contacted experts in the field and searched references of trials for any additional trials. SELECTION CRITERIA Randomised controlled trials investigating the effectiveness and safety of iron administration interventions compared to other iron administration interventions or placebo in the treatment of iron deficiency anaemia in inflammatory bowel disease. We considered both adults and children, with studies reporting outcomes of clinical, endoscopic, histologic or surgical remission as defined by study authors. DATA COLLECTION AND ANALYSIS Two review authors independently conducted data extraction and 'Risk of bias' assessment of included studies. We expressed dichotomous and continuous outcomes as risk ratios and mean differences with 95% confidence intervals. We assessed the certainty of the evidence using the GRADE methodology. MAIN RESULTS We included 11 studies (1670 randomised participants) that met the inclusion criteria. The studies compared intravenous iron sucrose vs oral iron sulphate (2 studies); oral iron sulphate vs oral iron hydroxide polymaltose complex (1 study); oral iron fumarate vs intravenous iron sucrose (1 study); intravenous ferric carboxymaltose vs intravenous iron sucrose (1 study); erythropoietin injection + intravenous iron sucrose vs intravenous iron sucrose + injection placebo (1 study); oral ferric maltol vs oral placebo (1 study); oral ferric maltol vs intravenous ferric carboxymaltose (1 study); intravenous ferric carboxymaltose vs oral iron sulphate (1 study); intravenous iron isomaltoside vs oral iron sulphate (1 study); erythropoietin injection vs oral placebo (1 study). All studies compared participants with CD and UC together, as well as considering a range of disease activity states. The primary outcome of number of responders, when defined, was stated to be an increase in haemoglobin of 20 g/L in all but two studies in which an increase in 10g/L was used. In one study comparing intravenous ferric carboxymaltose and intravenous iron sucrose, moderate-certainty evidence was found that intravenous ferric carboxymaltose was probably superior to intravenous iron sucrose, although there were responders in both groups (150/244 versus 118/239, RR 1.25, 95% CI 1.06 to 1.46, number needed to treat for an additional beneficial outcome (NNTB) = 9). In one study comparing oral ferric maltol to placebo, there was low-certainty evidence of superiority of the iron (36/64 versus 0/64, RR 73.00, 95% CI 4.58 to 1164.36). There were no other direct comparisons that found any difference in the primary outcomes, although certainty was low and very low for all outcomes, due to imprecision from sparse data and risk of bias varying between moderate and high risk. The reporting of secondary outcomes was inconsistent. The most common was the occurrence of serious adverse events or those requiring withdrawal of therapy. In no comparisons was there a difference seen between any of the intervention agents being studied, although the certainty was very low for all comparisons made, due to risk of bias and significant imprecision due to the low numbers of events. Time to remission, histological and biochemical outcomes were sparsely reported in the studies. None of the other secondary outcomes were reported in any of the studies. An analysis of all intravenous iron preparations to all oral iron preparations showed that intravenous administration may lead to more responders (368/554 versus 205/373, RR 1.17, 95% CI 1.05 to 1.31, NNTB = 11, low-certainty due to risk of bias and inconsistency). Withdrawals due to adverse events may be greater in oral iron preparations vs intravenous (15/554 versus 31/373, RR 0.39, 95% CI 0.20 to 0.74, low-certainty due to risk of bias, inconsistency and imprecision). AUTHORS' CONCLUSIONS Intravenous ferric carboxymaltose probably leads to more people having resolution of IDA (iron deficiency anaemia) than intravenous iron sucrose. Oral ferric maltol may lead to more people having resolution of IDA than placebo. We are unable to draw conclusions on which of the other treatments is most effective in IDA with IBD (inflammatory bowel disease) due to low numbers of studies in each comparison area and clinical heterogeneity within the studies. Therefore, there are no other conclusions regarding the treatments that can be made and certainty of all findings are low or very low. Overall, intravenous iron delivery probably leads to greater response in patients compared with oral iron, with a NNTB (number needed to treat) of 11. Whilst no serious adverse events were specifically elicited with any of the treatments studied, the numbers of reported events were low and the certainty of these findings very low for all comparisons, so no conclusions can be drawn. There may be more withdrawals due to such events when oral is compared with intravenous iron delivery. Other outcomes were poorly reported and once again no conclusions can be made as to the impact of IDA on any of these outcomes. Given the widespread use of many of these treatments in practice and the only guideline that exists recommending the use of intravenous iron in favour of oral iron, research to investigate this key issue is clearly needed. Considering the current ongoing trials identified in this review, these are more focussed on the impact in specific patient groups (young people) or on other symptoms (such as fatigue). Therefore, there is a need for studies to be performed to fill this evidence gap.
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Randomised clinical trial: intravenous vs oral iron for the treatment of anaemia after acute gastrointestinal bleeding
Ferrer-Barcelo L, Sanchis Artero L, Sempere Garcia-Arguelles J, Canelles Gamir P, P. Gisbert J, Ferrer-Arranz LM, Monzo Gallego A, Plana Campos L, Huguet Malaves JM, Lujan Sanchis M, et al
Alimentary pharmacology & therapeutics. 2019
Abstract
BACKGROUND Acute gastrointestinal bleeding is prevalent condition and iron deficiency anaemia is a common comorbidity, yet anaemia treatment guidelines for affected patients are lacking. AIM: To compare efficacy and safety of intravenous ferric carboxymaltose (FCM) and oral ferrous sulphate (FeSulf) in patients with anaemia secondary to non-variceal gastrointestinal bleeding METHODS A prospective 42-day study randomised 61 patients with haemoglobin <10 g/dL upon discharge (Day 0) to receive FCM (n = 29; Day 0: 1000 mg, Day 7: 500 or 1000 mg; per label) or FeSulf (n = 32; 325 mg/12 hours for 6 weeks). Outcome measures were assessed on Days 0 (baseline), 7, 21 and 42. The primary outcome was complete response (haemoglobin ≥12 g/dL [women], ≥13 g/dL [men]) after 6 weeks. RESULTS A higher proportion of complete response was observed in the FCM vs the FeSulf group at Days 21 (85.7% vs 45.2%; P = 0.001) and 42 (100% vs 61.3%; P < 0.001). Additionally, the percentage of patients with partial response (haemoglobin increment ≥2 g/dL from baseline) was significantly higher in the FCM vs the FeSulf group (Day 21:100% vs 67.7%; P = 0.001, Day 42:100% vs 74.2%; P = 0.003). At Day 42, normalisation of transferrin saturation to 25% or greater was observed in 76.9% of FCM vs 24.1% of FeSulf-treated patients (P < 0.001). No patient in the FCM group reported any adverse event vs 10 patients in the FeSulf group. CONCLUSION FCM provided greater and faster Hb increase and iron repletion, and was better tolerated than FeSulf in patients with iron deficiency anaemia secondary to non-variceal acute gastrointestinal bleeding.
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Improved Hemoglobin Response with Ferric Carboxymaltose in Patients with Gastrointestinal-Related Iron-Deficiency Anemia Versus Oral Iron
Lichtenstein GR, Onken JE
Digestive Diseases and Sciences. 2018;63((11):):3009-3019.
Abstract
AIMS: To compare the efficacy and safety of intravenous (IV) ferric carboxymaltose (FCM) versus oral iron and other IV iron therapies in patients with iron-deficiency anemia (IDA) resulting from gastrointestinal (GI) disorders. METHODS A pooled analysis of four prospective, randomized, active-controlled trials in patients with IDA was performed. Efficacy measures included change from baseline in hemoglobin (Hb), ferritin, and transferrin saturation (TSAT) and correlations of baseline Hb, ferritin, and TSAT to change in Hb. The incidence and type of adverse events were evaluated. RESULTS A total of 191 patients were evaluated. The mean change in Hb from baseline to the maximum value was 0.8 g/dL with oral iron (P = 0.001 vs. FCM), 2.2 g/dL with FCM, 2.0 g/dL with any IV iron (P = 0.391 vs. FCM), and 1.9 g/dL with iron sucrose (P = 0.329 vs. FCM). Patients treated with FCM and iron sucrose had larger increases in Hb. This effect may have been attributed to a lower baseline Hb level. Drug-related adverse events occurred in 11.9, 12, 26.2, and 25% and serious adverse events (SAEs) occurred in 6.9, 4, 9.8, and 12.5% of patients in the FCM, oral iron, other IV iron therapies, and iron sucrose groups, respectively. No SAEs were considered treatment related in the FCM group, compared with two treatment-related SAEs in two patients (6.3%) in the iron sucrose group. CONCLUSIONS FCM is an effective therapy in patients with IDA who have GI disorders and has a safety profile comparable to that of other IV iron agents.
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Systematic review with network meta-analysis: comparative efficacy and tolerability of different intravenous iron formulations for the treatment of iron deficiency anaemia in patients with inflammatory bowel disease
Aksan A, Isik H, Radeke HH, Dignass A, Stein J
Alimentary Pharmacology & Therapeutics. 2017;45((10):):1303-1318
Abstract
BACKGROUND Iron deficiency anaemia (IDA) is a common complication of inflammatory bowel disease (IBD) associated with reduced quality of life and increased hospitalisation rates. While the best way of treating IDA in IBD patients is not clearly established, current European guidelines recommend intravenous iron therapy in IBD patients with severe anaemia or intolerance to oral iron compounds. AIM: To compare the efficacy and tolerability of different intravenous iron formulations used to treat IDA in IBD patients in a systematic review and Bayesian network meta-analysis (NMA), PROSPERO registration number: 42016046565. METHODS In June 2016, we systematically searched for studies analysing efficacy and safety of intravenous iron for IDA therapy in IBD. Primary outcome was therapy response, defined as Hb normalisation or increase ≥2 g/dL. RESULTS Five randomised, controlled trials (n = 1143 patients) were included in a network meta-analysis. Only ferric carboxymaltose was significantly more effective than oral iron [OR=1.9, 95% CrI: (1.1;3.2)]. Rank probabilities showed ferric carboxymaltose to be most effective, followed by iron sucrose, iron isomaltose and oral iron. Pooled data from the systematic review (n = 1746 patients) revealed adverse event rates of 12.0%, 15.3%, 12.0%, 17.0% for ferric carboxymaltose, iron sucrose, iron dextran and iron isomaltose respectively. One drug-related serious adverse event (SAE) each was reported for ferric carboxymaltose and iron isomaltoside, and one possibly drug-related SAE for iron sucrose. CONCLUSIONS Ferric carboxymaltose was the most effective intravenous iron formulation, followed by iron sucrose. In addition, ferric carboxymaltose tended to be better tolerated. Thus, nanocolloidal IV iron products exhibit differing therapeutic and safety characteristics and are not interchangeable.
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Oral versus intravenous iron replacement therapy distinctly alters the gut microbiota and metabolome in patients with IBD
Lee T, Clavel T, Smirnov K, Schmidt A, Lagkouvardos I, Walker A, Lucio M, Michalke B, Schmitt-Kopplin P, Fedorak R, et al
Gut. 2016;66((5):):863-871
Abstract
OBJECTIVE Iron deficiency is a common complication in patients with IBD and oral iron therapy is suggested to exacerbate IBD symptoms. We performed an open-labelled clinical trial to compare the effects of per oral (PO) versus intravenous (IV) iron replacement therapy (IRT). DESIGN The study population included patients with Crohn's disease (CD; N=31), UC (N=22) and control subjects with iron deficiency (non-inflamed, NI=19). After randomisation, participants received iron sulfate (PO) or iron sucrose (IV) over 3 months. Clinical parameters, faecal bacterial communities and metabolomes were assessed before and after intervention. RESULTS Both PO and IV treatments ameliorated iron deficiency, but higher ferritin levels were observed with IV. Changes in disease activity were independent of iron treatment types. Faecal samples in IBD were characterised by marked interindividual differences, lower phylotype richness and proportions of Clostridiales. Metabolite analysis also showed separation of both UC and CD from control anaemic participants. Major shifts in bacterial diversity occurred in approximately half of all participants after IRT, but patients with CD were most susceptible. Despite individual-specific changes in phylotypes due to IRT, PO treatment was associated with decreased abundances of operational taxonomic units assigned to the species Faecalibacterium prausnitzii, Ruminococcus bromii, Dorea sp. and Collinsella aerofaciens. Clear IV-specific and PO-specific fingerprints were evident at the level of metabolomes, with changes affecting cholesterol-derived host substrates. CONCLUSIONS Shifts in gut bacterial diversity and composition associated with iron treatment are pronounced in IBD participants. Despite similar clinical outcome, oral administration differentially affects bacterial phylotypes and faecal metabolites compared with IV therapy. TRIAL REGISTRATION NUMBER clinicaltrial.gov (NCT01067547).