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Effect of Convalescent Plasma on Organ Support-Free Days in Critically Ill Patients With COVID-19: A Randomized Clinical Trial
Estcourt LJ, Turgeon AF, McQuilten ZK, McVerry BJ, Al-Beidh F, Annane D, Arabi YM, Arnold DM, Beane A, Bégin P, et al
Jama. 2021
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Editor's Choice
Abstract
IMPORTANCE The evidence for benefit of convalescent plasma for critically ill patients with COVID-19 is inconclusive. OBJECTIVE To determine whether convalescent plasma would improve outcomes for critically ill adults with COVID-19. DESIGN, SETTING, AND PARTICIPANTS The ongoing Randomized, Embedded, Multifactorial, Adaptive Platform Trial for Community-Acquired Pneumonia (REMAP-CAP) enrolled and randomized 4763 adults with suspected or confirmed COVID-19 between March 9, 2020, and January 18, 2021, within at least 1 domain; 2011 critically ill adults were randomized to open-label interventions in the immunoglobulin domain at 129 sites in 4 countries. Follow-up ended on April 19, 2021. INTERVENTIONS The immunoglobulin domain randomized participants to receive 2 units of high-titer, ABO-compatible convalescent plasma (total volume of 550 mL ± 150 mL) within 48 hours of randomization (n = 1084) or no convalescent plasma (n = 916). MAIN OUTCOMES AND MEASURES The primary ordinal end point was organ support-free days (days alive and free of intensive care unit-based organ support) up to day 21 (range, -1 to 21 days; patients who died were assigned -1 day). The primary analysis was an adjusted bayesian cumulative logistic model. Superiority was defined as the posterior probability of an odds ratio (OR) greater than 1 (threshold for trial conclusion of superiority >99%). Futility was defined as the posterior probability of an OR less than 1.2 (threshold for trial conclusion of futility >95%). An OR greater than 1 represented improved survival, more organ support-free days, or both. The prespecified secondary outcomes included in-hospital survival; 28-day survival; 90-day survival; respiratory support-free days; cardiovascular support-free days; progression to invasive mechanical ventilation, extracorporeal mechanical oxygenation, or death; intensive care unit length of stay; hospital length of stay; World Health Organization ordinal scale score at day 14; venous thromboembolic events at 90 days; and serious adverse events. RESULTS Among the 2011 participants who were randomized (median age, 61 [IQR, 52 to 70] years and 645/1998 [32.3%] women), 1990 (99%) completed the trial. The convalescent plasma intervention was stopped after the prespecified criterion for futility was met. The median number of organ support-free days was 0 (IQR, -1 to 16) in the convalescent plasma group and 3 (IQR, -1 to 16) in the no convalescent plasma group. The in-hospital mortality rate was 37.3% (401/1075) for the convalescent plasma group and 38.4% (347/904) for the no convalescent plasma group and the median number of days alive and free of organ support was 14 (IQR, 3 to 18) and 14 (IQR, 7 to 18), respectively. The median-adjusted OR was 0.97 (95% credible interval, 0.83 to 1.15) and the posterior probability of futility (OR <1.2) was 99.4% for the convalescent plasma group compared with the no convalescent plasma group. The treatment effects were consistent across the primary outcome and the 11 secondary outcomes. Serious adverse events were reported in 3.0% (32/1075) of participants in the convalescent plasma group and in 1.3% (12/905) of participants in the no convalescent plasma group. CONCLUSIONS AND RELEVANCE Among critically ill adults with confirmed COVID-19, treatment with 2 units of high-titer, ABO-compatible convalescent plasma had a low likelihood of providing improvement in the number of organ support-free days. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT02735707.
PICO Summary
Population
Critically ill patients with COVID-19 from 129 sites in 4 countries, enrolled in the ongoing REMAP-CAP trial (n= 2,011).
Intervention
2 units of high-titre, ABO-compatible convalescent plasma (n= 1,084).
Comparison
No convalescent plasma (n= 916).
Outcome
The median number of organ support-free days was 0 in the convalescent plasma group and 3 in the no convalescent plasma group. The in-hospital mortality rate was 37.3% for the convalescent plasma group and 38.4% for the no convalescent plasma group and the median number of days alive and free of organ support was 14 and 14, respectively. Serious adverse events were reported in 3% of participants in the convalescent plasma group and in 1.3% of participants in the no convalescent plasma group.
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Therapeutic Anticoagulation with Heparin in Critically Ill Patients with Covid-19
Goligher EC, Bradbury CA, McVerry BJ, Lawler PR, Berger JS, Gong, MN, Carrier M, Reynolds HR, Kumar A, Turgeon AF, et al
The New England Journal of Medicine. 2021
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Editor's Choice
Abstract
BACKGROUND Thrombosis and inflammation may contribute to morbidity and mortality among patients with coronavirus disease 2019 (Covid-19). We hypothesized that therapeutic-dose anticoagulation would improve outcomes in critically ill patients with Covid-19. METHODS In an open-label, adaptive, multiplatform, randomized clinical trial, critically ill patients with severe Covid-19 were randomly assigned to a pragmatically defined regimen of either therapeutic-dose anticoagulation with heparin or pharmacologic thromboprophylaxis in accordance with local usual care. The primary outcome was organ support-free days, evaluated on an ordinal scale that combined in-hospital death (assigned a value of -1) and the number of days free of cardiovascular or respiratory organ support up to day 21 among patients who survived to hospital discharge. RESULTS The trial was stopped when the prespecified criterion for futility was met for therapeutic-dose anticoagulation. Data on the primary outcome were available for 1098 patients (534 assigned to therapeutic-dose anticoagulation and 564 assigned to usual-care thromboprophylaxis). The median value for organ support-free days was 1 (interquartile range, -1 to 16) among the patients assigned to therapeutic-dose anticoagulation and was 4 (interquartile range, -1 to 16) among the patients assigned to usual-care thromboprophylaxis (adjusted proportional odds ratio, 0.83; 95% credible interval, 0.67 to 1.03; posterior probability of futility [defined as an odds ratio <1.2], 99.9%). The percentage of patients who survived to hospital discharge was similar in the two groups (62.7% and 64.5%, respectively; adjusted odds ratio, 0.84; 95% credible interval, 0.64 to 1.11). Major bleeding occurred in 3.8% of the patients assigned to therapeutic-dose anticoagulation and in 2.3% of those assigned to usual-care pharmacologic thromboprophylaxis. CONCLUSIONS In critically ill patients with Covid-19, an initial strategy of therapeutic-dose anticoagulation with heparin did not result in a greater probability of survival to hospital discharge or a greater number of days free of cardiovascular or respiratory organ support than did usual-care pharmacologic thromboprophylaxis. (REMAP-CAP, ACTIV-4a, and ATTACC ClinicalTrials.gov numbers, NCT02735707, NCT04505774, NCT04359277, and NCT04372589.).
PICO Summary
Population
Critically ill patients with severe COVID-19 (n= 1,098).
Intervention
Therapeutic-dose anticoagulation with heparin (n= 534).
Comparison
Usual-care pharmacologic thromboprophylaxis (n= 564).
Outcome
The median value for organ support-free days was 1 (interquartile range, -1 to 16) among the patients assigned to therapeutic-dose anticoagulation and was 4 (interquartile range, -1 to 16) among the patients assigned to usual-care thromboprophylaxis. The percentage of patients who survived to hospital discharge was similar in the two groups (62.7% and 64.5%, respectively). Major bleeding occurred in 3.8% of the patients assigned to therapeutic-dose anticoagulation and in 2.3% of those assigned to usual-care pharmacologic thromboprophylaxis.
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Safety and efficacy of erythropoiesis-stimulating agents in critically ill patients admitted to the intensive care unit: a systematic review and meta-analysis
Litton E, Latham P, Inman J, Luo J, Allan P
Intensive care medicine. 2019
Abstract
PURPOSE Severe immune dysregulation is common in patients admitted to the intensive care unit (ICU) and is associated with adverse outcomes. Erythropoietin-stimulating agents (ESAs) have immune-modulating and anti-apoptotic effects. However, their safety and efficacy in critically ill patients remain uncertain. We evaluated whether ESAs, administered to critically unwell adult patients admitted to the ICU, reduced mortality at hospital discharge. METHODS The search strategy was conducted according to a predetermined protocol and included OVID MEDLINE, OVID EMBASE and The Cochrane Central Register of Controlled Trials from inception until 20 May 2019. Publications were eligible for inclusion if they were randomized controlled trials (RCTs) including adult patients admitted to an ICU, that identified and reported a group receiving ESA therapy compared to a group not receiving ESA therapy and reported mortality. There were no language restrictions. RESULTS The systematic review included 21 studies with 5452 participants. In-hospital mortality, reported in 16 studies of which only one was at low risk of bias, was lower in the ESA group (276 of 2187 patients, 12.6%) than the comparator group (339 out of 2204 patients, 15.4%), [relative risk (RR) 0.82, 95% CI 0.71-0.94, P = 0.006, I(2) = 0.0%]. The RR of SAEs and thromboembolic events for the ESA and comparator groups were similar, RR 1.11 (95% CI 0.94-1.31, P = 0.228, I(2) 66%) and 1.22 (95% CI 0.95-1.58, P = 0.086, I(2) 47%), respectively. CONCLUSIONS In heterogenous populations of critically ill adults, evidence from RCTs of mainly low or unclear quality, suggests that ESA therapy may decrease mortality.
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Intravenous iron therapy for non-anaemic, iron-deficient adults
Miles LF, Litton E, Imberger G, Story D
The Cochrane database of systematic reviews. 2019;12:Cd013084
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Editor's Choice
Abstract
BACKGROUND Iron deficiency is one of the most common nutritional deficiencies, and has a number of physiological manifestations. Early, or non-anaemic iron deficiency can result in fatigue and diminished exercise capacity. Oral iron preparations have a high incidence of intolerable side effects, and are ineffective in certain forms of iron deficiency. Consequently, intravenous iron preparations are increasingly used in the treatment of non-anaemic iron deficiency. The newer, more stable iron preparations in particular purport to have a lower incidence of side effects, and are now used across a range of different patient populations. OBJECTIVES To assess the effects of intravenous iron therapy in the treatment of adults with non-anaemic iron deficiency. SEARCH METHODS On 18 October 2019 we electronically searched CENTRAL, MEDLINE, Embase, two further databases and two trials registries 2019. We handsearched the references of full-text extracted studies, and contacted relevant study authors for additional data. SELECTION CRITERIA We included randomised controlled trials that compared any intravenous iron preparation to placebo in adults. We excluded other forms of comparison such as oral iron versus placebo, intramuscular iron versus placebo, or intravenous iron studies where other iron preparations were used as the comparator. We also excluded studies involving erythropoietin therapy or obstetric populations. DATA COLLECTION AND ANALYSIS Two review authors screened references for eligibility, extracted data and assessed risk of bias. We resolved differences in opinion through discussion and consensus, and where necessary, involved a third review author to adjudicate disputes. We contacted study authors to request additional data where appropriate. The primary outcome measures were haemoglobin concentration at the end of follow-up, and quality-of-life scores at end of follow-up. Secondary outcome measures were serum ferritin, peak oxygen consumption (as measured by cardiopulmonary exercise testing), adverse effects (graded as mild to moderate and severe) and bacterial infection. We pooled data for continuous outcomes, which we then reported as mean differences (MDs) with 95% confidence intervals (CIs). We reported quality-of-life metrics as standardised mean difference (SMD), and then converted them back into a more familiar measure, the Piper Fatigue Scale. We analysed dichotomous outcomes as risk ratios (RRs). Given an expected degree of heterogeneity, we used a random-effects model for all outcomes. We performed the analysis with the software package Review Manager 5. MAIN RESULTS This review includes 11 studies with 1074 participants. Outcome metrics for which data were available (haemoglobin concentration, quality-of-life scores, serum ferritin, peak oxygen consumption and mild to moderate adverse effects) were similar across the included studies. The incidence of severe adverse events across all studies was zero. None of the studies measured bacterial infection as a specific outcome metric. Substantial heterogeneity influenced the results of the meta-analysis, arising from differing patient populations, definitions of iron deficiency, iron preparations and dosing regimens, and time to end of follow-up. Consequently, many outcomes are reported with small group sizes and wide confidence intervals, with a subsequent downgrading in the quality of evidence. The level of bias in many included studies was high, further reducing confidence in the robustness of the results. We found that intravenous iron therapy may lead to a small increase in haemoglobin concentration of limited clinical significance compared to placebo (MD 3.04 g/L, 95% CI 0.65 to 5.42; I(2) = 42%; 8 studies, 548 participants; low-quality evidence). Quality-of-life scores (Piper Fatigue Scale MD 0.73, 95% CI 0.29 to 1.18; I(2) = 0%; studies = 3) and peak oxygen consumption (MD 2.77 mL/kg/min, 95% CI -0.89 to 6.43; I(2) = 36%; 2 studies, 32 participants) were associated with very low-quality evidence, and we remain uncertain about the role of intravenous iron for these metrics. We were unable to present pooled estimates for the outcomes of serum ferritin at the end of follow-up or mild to moderate adverse effects due to extreme statistical heterogeneity. Ultimately, despite the results of the meta-analysis, the low- or very low-quality evidence for all outcomes precludes any meaningful interpretation of results beyond suggesting that further research is needed. We performed a Trial Sequential Analysis for all major outcomes, none of which could be said to have reached a necessary effect size. AUTHORS' CONCLUSIONS Current evidence is insufficient to show benefit of intravenous iron preparations for the treatment of non-anaemic iron deficiency across a variety of patient populations, beyond stating that it may result in a small, clinically insignificant increase in haemoglobin concentration. However, the certainty for even this outcome remains limited. Robust data for the effectiveness of intravenous iron for non-anaemic iron deficiency is still lacking, and larger studies are required to assess the effect of this therapy on laboratory, patient-centric, and adverse-effect outcomes.
PICO Summary
Population
Adults with non-anaemic iron deficiency, (11 studies, 1074 patients).
Intervention
Intravenous iron therapy.
Comparison
Placebo.
Outcome
Outcome metrics (haemoglobin concentration, quality-of-life scores, serum ferritin, peak oxygen consumption and mild to moderate adverse effects) were similar across the included studies. The incidence of severe adverse events across all studies was zero. None of the studies measured bacterial infection as a specific outcome metric. Substantial heterogeneity influenced the results of the meta-analysis, arising from differing patient populations, definitions of iron deficiency, iron preparations and dosing regimens, and time to end of follow-up. Intravenous iron therapy may lead to a small increase in haemoglobin concentration of limited clinical significance compared to placebo (MD 3.04 g/L). Quality-of-life scores (Piper Fatigue Scale MD 0.73, and peak oxygen consumption (MD 2.77 mL/kg/min, were associated with very low-quality evidence. We were unable to present pooled estimates for the outcomes of serum ferritin at the end of follow-up or mild to moderate adverse effects due to extreme statistical heterogeneity.
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Safety and efficacy of iron therapy on reducing red blood cell transfusion requirements and treating anaemia in critically ill adults: A systematic review with meta-analysis and trial sequential analysis
Shah A, Fisher SA, Wong H, Roy NB, McKechnie S, Doree C, Litton E, Stanworth SJ
Journal of Critical Care. 2018;49:162-171.
Abstract
PURPOSE To evaluate the safety (risk of infection) and efficacy (transfusion requirements, changes in haemoglobin (Hb)) of iron therapy in adult intensive care unit (ICU) patients. MATERIALS AND METHODS We systematically searched seven databases for all relevant studies until January 2018 and included randomized (RCT) studies comparing iron, by any route, with placebo/no iron. RESULTS 805 participants from 6 RCTs were included. Iron therapy, by any route, did not decrease the risk of requirement for a red blood cell (RBC) transfusion (Risk ratio (RR) 0.91, 95% CI 0.80 to 1.04, p=0.15) or mean number of RBCs transfused per participant (mean difference (MD) -0.30, 95% CI -0.68 to 0.07, p=0.15). Iron therapy did increase mean Hb concentration (MD 0.31g/dL, 95% CI 0.04 to 0.59, p=0.03). There was no difference in infection (RR 0.95, 95% CI 0.79 to 1.19, p=0.44). Trial Sequential Analysis suggests that the required participant numbers to detect or reject a clinically important effect of iron therapy on transfusion requirements or infection in ICU patients has not yet been reached. CONCLUSION Iron therapy results in a modest increase in Hb. The current evidence is inadequate to exclude an important effect on transfusion requirements or infection.
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Restricted fluid resuscitation in suspected sepsis associated hypotension (REFRESH): a pilot randomised controlled trial
Macdonald SPJ, Keijzers G, Taylor DM, Kinnear F, Arendts G, Fatovich DM, Bellomo R, McCutcheon D, Fraser JF, Ascencio-Lane JC, et al
Intensive Care Medicine. 2018;44((12):):2070-2078.
Abstract
PURPOSE To determine if a regimen of restricted fluids and early vasopressor compared to usual care is feasible for initial resuscitation of hypotension due to suspected sepsis. METHODS A prospective, randomised, open-label, clinical trial of a restricted fluid resuscitation regimen in the first 6 h among patients in the emergency department (ED) with suspected sepsis and a systolic blood pressure under 100 mmHg, after minimum 1000 ml of IV fluid. Primary outcome was total fluid administered within 6 h post randomisation. RESULTS There were 99 participants (50 restricted volume and 49 usual care) in the intention-to-treat analysis. Median volume from presentation to 6 h in the restricted volume group was 2387 ml [first to third quartile (Q1-Q3) 1750-2750 ml]; 30 ml/kg (Q1-Q3 32-39 ml/kg) vs. 3000 ml (Q1-Q3 2250-3900 ml); 43 ml/kg (Q1-Q3 35-50 ml/kg) in the usual care group (p < 0.001). Median duration of vasopressor support was 21 h (Q1-Q3 9-42 h) vs. 33 h (Q1-Q3 15-50 h), (p = 0.13) in the restricted volume and usual care groups, respectively. At 90-days, 4 of 48 (8%) in the restricted volume group and 3 of 47 (6%) in the usual care group had died. Protocol deviations occurred in 6/50 (12%) in restricted group and 11/49 (22%) in the usual care group, and serious adverse events in four cases (8%) in each group. CONCLUSIONS A regimen of restricted fluids and early vasopressor in ED patients with suspected sepsis and hypotension appears feasible. Illness severity was moderate and mortality rates low. A future trial is necessary with recruitment of high-risk patients to determine effects on clinical outcomes in this setting.
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Intravenous iron or placebo for anaemia in intensive care: the IRONMAN multicentre randomized blinded trial : a randomized trial of IV iron in critical illness
Litton E, Baker S, Erber WN, Farmer S, Ferrier J, French C, Gummer J, Hawkins D, Higgins A, Hofmann A, et al
Intensive Care Medicine. 2016;42((11):):1715-1722
Abstract
PURPOSE Both anaemia and allogenic red blood cell transfusion are common and potentially harmful in patients admitted to the intensive care unit. Whilst intravenous iron may decrease anaemia and RBC transfusion requirement, the safety and efficacy of administering iron intravenously to critically ill patients is uncertain. METHODS The multicentre, randomized, placebo-controlled, blinded Intravenous Iron or Placebo for Anaemia in Intensive Care (IRONMAN) study was designed to test the hypothesis that, in anaemic critically ill patients admitted to the intensive care unit, early administration of intravenous iron, compared with placebo, reduces allogeneic red blood cell transfusion during hospital stay and increases the haemoglobin level at the time of hospital discharge. RESULTS Of 140 patients enrolled, 70 were assigned to intravenous iron and 70 to placebo. The iron group received 97 red blood cell units versus 136 red blood cell units in the placebo group, yielding an incidence rate ratio of 0.71 [95 % confidence interval (0.43-1.18), P = 0.19]. Overall, median haemoglobin at hospital discharge was significantly higher in the intravenous iron group than in the placebo group [107 (interquartile ratio IQR 97-115) vs. 100 g/L (IQR 89-111), P = 0.02]. There was no significant difference between the groups in any safety outcome. CONCLUSIONS In patients admitted to the intensive care unit who were anaemic, intravenous iron, compared with placebo, did not result in a significant lowering of red blood cell transfusion requirement during hospital stay. Patients who received intravenous iron had a significantly higher haemoglobin concentration at hospital discharge. The trial was registered at http://www.anzctr.org.au as # ACTRN12612001249842.
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Intravenous iron or placebo for anaemia in the ICU: the IRONMAN multicentre randomized blinded trial
Litton E
Critical Care Medicine. 2016;44((12 Suppl 1)):225.. 594.
Abstract
Learning Objectives: Both anaemia and allogenic red blood cell transfusion are common and potentially harmful in patients admitted to the intensive care unit. Whilst intravenous iron may decrease anaemia and RBC transfusion requirement, safety and efficacy in critically ill patients is uncertain. Methods: The multicentre, randomized, placebo-controlled, blinded, Intravenous Iron or Placebo for Anaemia in Intensive Care (IRONMAN) study was designed to test the hypothesis that, in anaemic, critically ill patients admitted to the intensive care unit, early administration of intravenous iron, compared with placebo, reduces allogenic red blood cell transfusion and increases haemoglobin to hospital discharge. Results: Of 140 patients enrolled, 70 were assigned to intravenous iron and 70 to placebo. The iron group received 97 red blood cell units versus 136 red blood cell unit in the placebo group, incidence rate ratio 0.71 [95% confidence interval (0.43-1.18) P=0.19]. Overall, median haemoglobin at hospital discharge was significantly higher in the intravenous iron group compared with the placebo group (107 (IQR 97-115) vs. 100 g/L (IQR 89-111), P=0.02). There was no significant difference between the groups in any safety outcome. Conclusions: In patients admitted to the intensive care unit who were anaemic, intravenous iron compared with placebo, did not result in a significant difference in red blood cell transfusion at hospital discharge. Patients who received intravenous iron had a significantly higher haemoglobin at hospital discharge.
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The IRONMAN trial: a protocol for a multicentre randomised placebo-controlled trial of intravenous iron in intensive care unit patients with anaemia
Litton E, Baker S, Erber W, French C, Ferrier J, Hawkins D, Higgins AM, Hofmann A, Keulenaer BL, Farmer S, et al
Critical Care & Resuscitation. 2014;16((4):):285-90.
Abstract
BACKGROUND Allogeneic red blood cell (RBC) transfusion is associated with significant increases in mortality and major morbidity in patients admitted to the intensive care unit, and the blood supplies it requires are an increasingly scarce and costly resource. Despite high levels of compliance with recommended transfusion thresholds in the ICU, RBC transfusion remains common. Novel interventions to reduce the incidence of RBC transfusion are required. OBJECTIVE To describe the study protocol for a randomised controlled trial, the Intravenous Iron or Placebo for Anaemia in Intensive Care (IRONMAN) trial, comparing intravenous (IV) iron with placebo in patients who are admitted to an ICU and are anaemic. DESIGN, SETTING, PARTICIPANTS AND INTERVENTION A Phase IIb multicentre, randomised, placebo-controlled trial. Patients admitted to the ICU with a haemoglobin (Hb) level < 100 g/L and predicted to require critical care beyond the next calendar day will be randomly assigned in a 1 : 1 ratio to receive IV ferric carboxymaltose (500 mg) or placebo. MAIN OUTCOME MEASURES The primary end point will be the mean number of RBC units transfused from study enrolment to discharge from hospital. Secondary end points will include change in Hb level and incidence of nosocomial infection. RESULTS AND CONCLUSIONS The IRONMAN trial is designed to determine whether IV iron administered to patients admitted to an ICU and who are anaemic is associated with a reduction in RBC transfusion, compared with placebo in addition to standard care. The results of this trial may determine whether a Phase III trial of IV iron in ICUs is feasible. TRIAL REGISTRATION Australian New Zealand Clinical Trials Registry (ACTRN12612001249842). IS 1441-2772
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Safety and efficacy of intravenous iron therapy in reducing requirement for allogeneic blood transfusion: systematic review and meta-analysis of randomised clinical trials
Litton E, Xiao J, Ho KM
Bmj. 2013;347:f4822.
Abstract
OBJECTIVES To evaluate the efficacy and safety of intravenous iron, focusing primarily on its effects on haemoglobin, requirement for transfusion, and risk of infection. DESIGN Systematic review and meta-analysis of randomised controlled trials investigating the safety and efficacy of intravenous iron therapy. DATA SOURCES Randomised controlled trials from Medline, Embase, and the Cochrane Central Register of Controlled Trials from 1966 to June 2013, with no language restrictions. ELIGIBILITY CRITERIA FOR SELECTING STUDIES Eligible trials were randomised controlled trials of intravenous iron compared with either no iron or oral iron. Crossover and observational studies were excluded. MAIN OUTCOME MEASURES Change in haemoglobin concentration and risk of allogeneic red blood cell transfusion (efficacy) and risk of infection (safety). RESULTS Of the 75 trials meeting the inclusion criteria, 72 studies including 10 605 patients provided quantitative outcome data for meta-analysis. Intravenous iron was associated with an increase in haemoglobin concentration (standardised mean difference 6.5 g/L, 95% confidence interval 5.1 g/L to 7.9 g/L) and a reduced risk of requirement for red blood cell transfusion (risk ratio 0.74, 95% confidence interval 0.62 to 0.88), especially when intravenous iron was used with erythroid stimulating agents (ESAs) or in patients with a lower baseline plasma ferritin concentration. There were no significant interactions between the efficacy of intravenous iron and type or dose administered. Intravenous iron was, however, associated with a significant increase in risk of infection (relative risk 1.33, 95% confidence interval 1.10 to 1.64) compared with oral or no iron supplementation. The results remained similar when only high quality trials were analysed. CONCLUSIONS Intravenous iron therapy is effective in increasing haemoglobin concentration and reducing the risk of allogeneic red blood cell transfusion and could have broad applicability to a range of acute care settings. This potential benefit is counterbalanced by a potential increased risk of infection.