1.
Iron therapy for preoperative anaemia
Ng O, Keeler BD, Mishra A, Simpson JA, Neal K, Al-Hassi HO, Brookes MJ, Acheson AG
The Cochrane database of systematic reviews. 2019;12:Cd011588
Abstract
BACKGROUND Preoperative anaemia is common and occurs in 5% to 76% of patients preoperatively. It is associated with an increased risk of perioperative allogeneic blood transfusion, longer hospital stay, and increased morbidity and mortality. Iron deficiency is one of the most common causes of anaemia. Oral and intravenous iron therapy can be used to treat anaemia. Parenteral iron preparations have been shown to be more effective in conditions such as inflammatory bowel disease, chronic heart failure and postpartum haemorrhage due to rapid correction of iron stores. A limited number of studies has investigated iron therapy for the treatment of preoperative anaemia. The aim of this Cochrane Review is to summarise the evidence for iron supplementation, both enteral and parenteral, for the management of preoperative anaemia. OBJECTIVES To evaluate the effects of preoperative iron therapy (enteral or parenteral) in reducing the need for allogeneic blood transfusions in anaemic patients undergoing surgery. SEARCH METHODS We ran the search on 30 July 2018. We searched the Cochrane Injuries Group's Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL, the Cochrane Library), Ovid MEDLINE(R), Ovid MEDLINE(R) In-Process & Other Non-Indexed Citations, Ovid MEDLINE(R) Daily and Ovid OLDMEDLINE(R), Embase Classic and Embase (Ovid), CINAHL Plus (EBSCO), PubMed, and clinical trials registries, and we screened reference lists. We ran a top-up search on 28 November 2019; one study is now awaiting classification. SELECTION CRITERIA We included all randomised controlled trials (RCTs) that compared preoperative iron monotherapy to placebo, no treatment, standard care or another form of iron therapy for anaemic adults undergoing surgery. We defined anaemia as haemoglobin values less than 13 g/dL for males and 12 g/dL for non-pregnant females. DATA COLLECTION AND ANALYSIS Two review authors collected data and a third review author checked all collected data. Data were collected on the proportion of patients who receive a blood transfusion, the amount of blood transfused per patient (units), quality of life, ferritin levels and haemoglobin levels, measured as continuous variables at the following predetermined time points: pretreatment (baseline), preoperatively but postintervention, and postoperatively. We performed statistical analysis using the Cochrane software, Review Manager 5. We summarised outcome data in tables and forest plots. We used the GRADE approach to describe the quality of the body of evidence. MAIN RESULTS Six RCTs, with a total of 372 participants, evaluated preoperative iron therapy to correct anaemia before planned surgery. Four studies compared iron therapy (either oral (one study) or intravenous (three studies)) with no treatment, placebo or usual care, and two studies compared intravenous iron therapy with oral iron therapy. Iron therapy was delivered over a range of periods that varied from 48 hours to three weeks prior to surgery. The 372 participants in our analysis fall far short of the 819 required - as calculated by our information size calculation - to detect a 30% reduction in blood transfusions. Five trials, involving 310 people, reported the proportion of participants who received allogeneic blood transfusions. Meta-analysis of iron therapy versus placebo or standard care showed no difference in the proportion of participants who received a blood transfusion (risk ratio (RR) 1.21, 95% confidence interval (CI) 0.87 to 1.70; 4 studies, 200 participants; moderate-quality evidence). Only one study that compared oral versus intravenous iron therapy measured this outcome, and reported no difference in risk of transfusion between groups. There was no difference between the iron therapy and placebo/standard care groups for haemoglobin level preoperatively at the end of the intervention (mean difference (MD) 0.63 g/dL, 95% CI -0.07 to 1.34; 2 studies, 83 participants; low-quality evidence). However, intravenous iron therapy produced an increase in preoperative postintervention haemoglobin levels compared with oral iron (MD 1.23 g/dL, 95% CI 0.80 to 1.65; 2 studies, 172 participants; low-quality evidence). Ferritin levels were increased by intravenous iron, both when compared to standard care ((MD 149.00, 95% CI 25.84 to 272.16; 1 study, 63 participants; low-quality evidence) or to oral iron (MD 395.03 ng/mL, 95% CI 227.72 to 562.35; 2 studies, 151 participants; low-quality evidence). Not all studies measured quality of life, short-term mortality or postoperative morbidity. Some measured the outcomes, but did not report the data, and the studies which did report the data were underpowered. Therefore, uncertainty remains regarding these outcomes. The inclusion of new research in the future is very likely to change these results. AUTHORS' CONCLUSIONS The use of iron therapy for preoperative anaemia does not show a clinically significant reduction in the proportion of trial participants who received an allogeneic blood transfusion compared to no iron therapy. Results for intravenous iron are consistent with a greater increase in haemoglobin and ferritin when compared to oral iron, but do not provide reliable evidence. These conclusions are drawn from six studies, three of which included very small numbers of participants. Further, well-designed, adequately powered, RCTs are required to determine the true effectiveness of iron therapy for preoperative anaemia. Two studies are currently in progress, and will include 1500 randomised participants.
2.
Iron therapy for pre-operative anaemia
Ng O, Keeler BD, Mishra A, Simpson A, Neal K, Brookes MJ, Acheson AG
Cochrane Database of Systematic Reviews.. 2015;((12)):CD011588.
Abstract
BACKGROUND Pre-operative anaemia is common and occurs in up to 76% of patients. It is associated with increased peri-operative allogeneic blood transfusions, longer hospital lengths of stay and increased morbidity and mortality. Iron deficiency is one of the most common causes of this anaemia. Oral iron therapy has traditionally been used to treat anaemia but newer, safer parenteral iron preparations have been shown to be more effective in other conditions such as inflammatory bowel disease, chronic heart failure and post-partum haemorrhage. A limited number of studies look at iron therapy for the treatment of pre-operative anaemia. The aim of this Cochrane review is to summarise the evidence for use of iron supplementation, both enteral and parenteral, for the management of pre-operative anaemia. OBJECTIVES The objective of this review is to evaluate the effects of pre-operative iron therapy (enteral or parenteral) in reducing the need for allogeneic blood transfusions in anaemic patients undergoing surgery. SEARCH METHODS We ran the search on 25 March 2015. We searched the Cochrane Injuries Group's Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), Ovid MEDLINE(R), Ovid MEDLINE(R) In-Process & Other Non-Indexed Citations, Ovid MEDLINE(R) Daily and Ovid OLDMEDLINE(R), EMBASE Classic and EMBASE (Ovid), CINAHL Plus (EBSCO), PubMed, clinical trials registries, conference abstracts, and we screened reference lists. SELECTION CRITERIA We included all randomised controlled trials (RCTs) which compared pre-operative iron monotherapy to placebo, no treatment, standard of care or another form of iron therapy for anaemic adults undergoing surgery. Anaemia was defined by haemoglobin values less than 13 g/dL for males and 12 g/dL for non-pregnant females. DATA COLLECTION AND ANALYSIS Data were collected by two authors on the proportion of patients who receive a blood transfusion, amount of blood transfused per patient (units) and haemoglobin measured as continuous variables at pre-determined time-points: pre-treatment, pre-operatively but post-treatment, and post-operatively. Statistical analysis was performed using the Cochrane statistical software, Review Manager 2014. Outcome data were summarised in tables and a forest plot. MAIN RESULTS Three prospective randomised controlled studies evaluated pre-operative iron therapy to correct anaemia (two in colorectal and one in gynaecological surgery) and included 114 patients in total. One compared oral iron versus standard care (Lidder 2007); one intravenous iron versus control (Edwards 2009); and one study compared oral versus intravenous iron (Kim 2009). Both colorectal trials reported the primary outcome (proportion of patients who received allogeneic blood transfusions) and meta-analysis showed a reduction in blood transfusions with the administration of iron therapy, but the reduction was not statistically significant (risk ratio (RR) 0.56, 95% confidence interval (CI) 0.27 to 1.18). All studies reported haemoglobin change but data for the anaemic patients were only available for two studies (Edwards 2009 and Kim 2009). Edwards 2009 showed no difference in haemoglobin at the end of treatment pre-operatively. The intravenous versus oral iron study showed an increase in haemoglobin with intravenous iron at the end of treatment pre-operatively (MD 1.90 g/dL, 95% CI 1.16 to 2.64; participants = 56), but the results are at high risk of bias because participants with less than 80% compliance with therapy were excluded from the analysis and compliance was lower in the oral iron group due to the side-effects of treatment (Kim 2009).None of the studies reported quality of life, short- or long-term mortality or post-operative morbidity. AUTHORS' CONCLUSIONS The use of iron therapy for pre-operative anaemia does not show a statistically significant reduction in the proportion of patients who received an allogeneic blood transfusion compared to no iron therapy. However, the 38 patients in our analysis falls far short of the 8