Associations of nadir haemoglobin level and red blood cell transfusion with mortality and length of stay in surgical specialties: a retrospective cohort study

A Propensity-Matched Cohort Study of Intravenous Iron versus Red Cell Transfusions for Preoperative Iron-Deficiency Anemia

BACKGROUND

While preoperative anemia is associated with adverse perioperative outcomes, the benefits of treatment with iron replacement versus red blood cell (RBC) transfusion remain uncertain. We used a national database to establish trends in preoperative iron-deficiency anemia (IDA) treatment and to test the hypothesis that treatment with preoperative iron may be superior to RBC transfusion.

METHODS

This study is a propensity-matched retrospective cohort analysis from 2003 to 2023 using TriNetX Research Network, which included surgical patients diagnosed with IDA within 3 months preoperatively. After matching for surgery type and comorbidities, we compared a cohort of patients with preoperative IDA who were treated with preoperative intravenous (IV) iron but not RBCs (n = 77,179), with a cohort receiving preoperative RBCs but not IV iron (n = 77,179). Propensity-score matching was performed for age, ethnicity, race, sex, overweight and obesity, type 2 diabetes, hyperlipidemia, essential hypertension, heart failure, chronic ischemic heart disease, neoplasms, hypothyroidism, chronic kidney disease, nicotine dependence, surgery type, and lab values from the day of surgery including ferritin, transferrin, and hemoglobin split into low (<7 g/dL), medium (7-<12 g/dL), and high (≥12 g/dL) to account for anemia severity. The primary outcome was 30-day postoperative mortality with the secondary outcomes being 30-day morbidity, postoperative hemoglobin level, and 30-day postoperative RBC transfusion.

RESULTS

Compared with RBC transfusion, preoperative IV iron was associated with lower risk of postoperative mortality (n = 2550/77,179 [3.3%] vs n = 4042/77,179 [5.2%]; relative risk [RR], 0.63, 95% confidence interval [CI], 0.60-0.66), and a lower risk of postoperative composite morbidity (n = 14,174/77,179 [18.4%] vs n = 18,632/77,179 [24.1%]; RR, 0.76, 95% CI, 0.75-0.78) (both P = .001 after Bonferroni adjustment). Compared with RBC transfusion, IV iron was also associated with a higher hemoglobin in the 30-day postoperative period (10.1 ± 1.8 g/dL vs 9.4 ± 1.7 g/dL, P = .001 after Bonferroni adjustment) and a reduced incidence of postoperative RBC transfusion (n = 3773/77,179 [4.9%] vs n = 12,629/77,179 [16.4%]; RR, 0.30, 95% CI, 0.29-0.31).

CONCLUSIONS

In a risk-adjusted analysis, preoperative IDA treatment with IV iron compared to RBC transfusion was associated with a reduction in 30-day postoperative mortality and morbidity, a higher 30-day postoperative hemoglobin level, and reduced postoperative RBC transfusion. This evidence represents a promising opportunity to improve patient outcomes and reduce blood transfusions and their associated risk and costs.

Impact of red blood cell transfusion and hemoglobin threshold on 1-year mortality among surgical sepsis survivors: A propensity score matching study

BACKGROUND

Despite the fact that red blood cell (RBC) transfusion is commonly applied in surgical intensive care unit (ICU), the effect of RBC transfusion on long-term outcomes remains undetermined. We aimed to explore the association between RBC transfusion and the long-term prognosis of surgical sepsis survivors.

METHODS

This retrospective study was conducted on adult sepsis patients admitted to a tertiary surgical ICU center in China. Patients were divided into transfusion and non-transfusion groups based on the presence of RBC transfusion. Propensity score matching (PSM) and inverse probability of treatment weighting (IPTW)were performed to balance the potential confounders.

RESULTS

A total of 1421 surgical sepsis survivors were enrolled, including 403 transfused patients and 1018 non-transfused patients. There was a significant difference in 1-year mortality between the two groups (23.1 ​% vs 12.7 ​%, HR: 1.539, 95 ​% confidence interval [CI]: 1.030-2.299, P ​< ​0.001). After PSM and IPTW, transfused patients still showed significantly increased 1-year mortality risks compared to non-transfused individuals (PSM: 23.6 ​% vs 15.9 ​%, HR 1.606, 95 ​% CI 1.036-2.488 ​P ​= ​0.034; IPTW: 20.1 ​% vs 12.9 ​%, HR 1.600, 95 ​% CI 1.040-2.462 ​P ​= ​0.032). Among patients with nadir hemoglobin below 70 ​g/L, 1-year mortality risks in both groups were similar (HR 1.461, 95 ​% CI 0.909-2.348, P ​= ​0.118). However, among patients with nadir hemoglobin above 70 ​g/L, RBC transfusion was correlated with increased 1-year mortality risk (HR 1.556, 95 ​% CI 1.020-2.374, P ​= ​0.040).

CONCLUSION

For surgical sepsis survivors, RBC transfusion during ICU stay was associated with increased 1-year mortality, especially when patients show hemoglobin levels above 70 ​g/L.

A further update on mortality and morbidity in patients with very low hemoglobin levels who decline blood transfusion

BACKGROUND

In the past two decades, researchers have published mortality and morbidity rates in patients with very low hemoglobin levels declining blood transfusion. The clinical knowledge and tools available for the management of patients who decline transfusions have grown since these publications. The aim of our study was to provide a further update on outcomes associated with severe anemia in these patients.

STUDY DESIGN AND METHODS

A retrospective observational study of patients declining allogeneic blood transfusions with nadir hemoglobin levels ≤8 g/dL treated at The Institute for Blood Management, HELIOS Klinikum Gotha, Germany. Outcomes were in-hospital mortality within 30 days and composite morbidity or mortality, with morbidity events defined as acute myocardial infarction, cardiac failure, wound infection, arrhythmia, and pneumonia.

RESULTS

Between June 2008 and June 2021, The Institute for Blood Management treated 2841 admissions of which 159 (5.6%) recorded nadir hemoglobin levels ≤8 g/dL. Of these, five (3.1%) patients died in hospital within 30 days, including four (4.8%) patients admitted for surgical procedures and one (1.4%) medical admission. There was a significant increase in the unadjusted proportion of composite morbidity or mortality events with severity of nadir hemoglobin, with each gram decrease in hemoglobin associated with a 1.48 (95% confidence interval = 1.05-2.09; p = .025) times increase.

CONCLUSION

Our comparatively lower proportion of patients reaching hemoglobin levels ≤8 g/dL and lower mortality rates suggest outcomes in patients with severe anemia is modifiable with the application of current patient blood management and bloodless medicine and surgery strategies.

Noninvasive hemoglobin monitoring for maintaining hemoglobin concentration within the target range during major noncardiac surgery: A randomized controlled trial

STUDY OBJECTIVE

The effect of noninvasive CO-oximetry hemoglobin (SpHb) monitoring on the clinical outcomes of patients undergoing surgery remains unclear. This trial aimed to evaluate whether SpHb monitoring helps maintain hemoglobin levels within a predefined target range during major noncardiac surgeries with a potential risk of intraoperative hemorrhage.

DESIGN

A single-center, prospective, randomized controlled trial.

SETTING

University hospital.

PATIENTS

One hundred and thirty patients undergoing elective noncardiac surgery with a potential risk of hemorrhage.

INTERVENTIONS

Patients were randomly allocated to undergo either SpHb-guided management (SpHb group) or usual care (control group).

MEASUREMENTS

The primary outcome was the rate of deviation of the total hemoglobin concentration (determined from laboratory testing) from a pre-specified target range (8-14 g/dL). This was defined as the number of laboratory tests revealing such deviations divided by the total number of laboratory tests performed during the surgery.

MAIN RESULTS

The primary outcome occurred significantly less frequently in the SpHb group as compared to that in the control group (15/555 [2.7%]) vs. 68/598 [11.4%]; relative risk, 0.24; 95% confidence interval, 0.13-0.41; P < 0.001). Fewer point-of-care blood tests were performed in the SpHb group than in the control group (median [interquartile range], 2 [1-4] vs. 4 [2-5]; P < 0.001). There were no significant intergroup differences in the number of patients who received red blood cell transfusions during surgery (SpHb vs. control, 33.8% vs. 46.2%; P = 0.201). The incidence of unnecessary red blood cell preparation (>2 units) was lower in the SpHb group than in the control group (3.1% vs. 16.9%; P = 0.024).

CONCLUSIONS

Compared with routine care, SpHb-guided management resulted in significantly lower rates of hemoglobin deviation outside the target range intraoperatively in patients undergoing major noncardiac surgeries with a potential risk of hemorrhage.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov (identifier: NCT03816514).

Determining sex-specific preoperative haemoglobin levels associated with intraoperative red blood cell transfusion in cardiac surgery: a retrospective cohort study

BACKGROUND

Anaemic cardiac surgery patients are at greater risk of intraoperative red blood cell transfusion. This study questions the application of the World Health Organization population-based anaemia thresholds (haemoglobin <120 g L-1 in non-pregnant females and <130 g L-1 in males) as appropriate preoperative optimisation targets for cardiac surgery.

METHODS

A retrospective cohort study was conducted on adults ≥18 yr old undergoing cardiopulmonary bypass surgery. Logistic regression was applied to define sex-specific preoperative haemoglobin concentrations with reduced probability of intraoperative red blood cell transfusion for cardiac surgery patients.

RESULTS

Data on 4384 male and 1676 female patients were analysed. Binarily stratified multivariable logistic regression odds of receiving intraoperative red blood cell transfusion increased in cardiac surgery patients >45 yr old (odds ratio [OR] 1.84; 95% confidence interval [CI] 1.33-2.55), surgery urgency <30 days (OR 2.03; 95% CI 1.66-2.48), combined coronary artery bypass grafting and valve surgery, or other surgery types (OR 2.24; 95% CI 1.87-2.67), and female sex (OR 1.92; 95% CI 1.62-2.28). The odds decreased by 8.4% with each 1 g L-1 increase in preoperative haemoglobin (OR 0.92; 95% CI 0.91-0.92). Logistic regression predicted females required a preoperative haemoglobin concentration of 133 g L-1 and males 127 g L-1 to have a 15% probability of intraoperative transfusion.

CONCLUSIONS

The World Health Organization female anaemia threshold of haemoglobin <120 g L-1 disproportionately disadvantages female cardiac surgery patients. A preoperative haemoglobin concentration ≥130 g L-1 in adult cardiac surgery patients would minimise their overall probability of intraoperative red blood cell transfusion to <15%.

Perioperative inappropriate red blood cell transfusions significantly increase total costs in elective surgical patients, representing an important economic burden for hospitals

Background

Red blood cell (RBC) transfusions in surgical patients are associated with increased morbidity a hospital stay. However, little is known about how clinical and economic outcomes differ between appropriately and inappropriately transfused patients. We hypothesized that inappropriate RBC transfusions in elective surgical patients would significantly increase hospital cost. The aim of this study was to quantify the economic burden associated with inappropriate RBC transfusions.

Methods

We retrospectively included all adult patients admitted for elective non-cardiac surgery between January 2014 and March 2020. Patients were divided into three groups (not transfused, appropriately transfused and inappropriately transfused). The primary outcome was the excess in hospital cost in patients inappropriately transfused compared to non-transfused patients. Costs were calculated using a bottom–up approach and involving cost calculation on a granular level. According to international guidelines, transfusions were considered appropriate if administered with an ASA score of 1–2 and the last hemoglobin level measured before transfusion < 70 g/L, or with an ASA score ≥ 3 and the last hemoglobin level < 80 g/L. Cases where RBC transfusions were deemed necessary regardless of the Hb levels were reviewed by the patient blood management (PBM) board and classified accordingly. Secondary outcomes included total transfusion rate, transfusion index, and length of hospital stay. Statistical analysis was carried out by multivariable regression models.

Results

During the study period there were 54,922 consecutive surgical admissions, of these 1,997 received an RBC transfusion, with 1,125 considered inappropriate. The adjusted cost of each inappropriate RBC transfusions was estimated in United States dollars (USD) 9,779 (95% CI, 9,358 – 10,199; p < 0.001) and totaled USD 11,001,410 in our series. Inappropriately transfused patients stayed 1.6 times (95% CI, 1.5–1.6; p < 0.001) longer in hospital (10.6 days vs. 6.7 days) than non-transfused patients and a mean 2.35 RBC units per patient were administered.

Conclusion

Inappropriate RBC transfusions in elective surgical patients seem to be common and may represent a significant economic burden. In our experience, inappropriate transfusions significantly increased hospital costs by an average of USD 9,779 compared to non-transfused patients. Through specific PBM policy, hospitals may improve cost-effectiveness of their elective surgical activity by lowering inappropriate transfusions.

A Global Definition of Patient Blood Management

While patient blood management (PBM) initiatives are increasingly adopted across the globe as part of standard of care, there is need for a clear and widely accepted definition of PBM. To address this, an expert group representing PBM organizations, from the International Foundation for Patient Blood Management (IFPBM), the Network for the Advancement of Patient Blood Management, Haemostasis and Thrombosis (NATA), the Society for the Advancement of Patient Blood Management (SABM), the Western Australia Patient Blood Management (WAPBM) Group, and OnTrac (Ontario Nurse Transfusion Coordinators) convened and developed this definition: "Patient blood management is a patient-centered, systematic, evidence-based approach to improve patient outcomes by managing and preserving a patient's own blood, while promoting patient safety and empowerment." The definition emphasizes the critical role of informed choice. PBM involves the timely, multidisciplinary application of evidence-based medical and surgical concepts aimed at screening for, diagnosing and appropriately treating anemia, minimizing surgical, procedural, and iatrogenic blood losses, managing coagulopathic bleeding throughout the care and supporting the patient while appropriate treatment is initiated. We believe that having a common definition for PBM will assist all those involved including PBM organizations, hospital administrators, individual clinicians and policy makers to focus on the appropriate issues when discussing and implementing PBM. The proposed definition is expected to continue to evolve, making this endeavor a work in progress.

Postoperative Noninvasive Hemoglobin Monitoring Is Useful to Prevent Unnoticed Postoperative Anemia and Inappropriate Blood Transfusion in Patients Undergoing Total Hip or Knee Arthroplasty: A Randomized Controlled Trial

Introduction

Postoperative nadir hemoglobin (Hb) is related to a longer length of stay for geriatric patients undergoing orthopedic surgery. We investigated whether postoperative pulse Hb (SpHb) measurement is useful for avoiding anemia and inappropriate blood transfusion after total hip arthroplasty and total knee arthroplasty.

Material and Methods

This prospective randomized controlled study included 150 patients randomly assigned to receive blood transfusion, either guided by SpHb monitoring (SpHb group) or based on the surgeons’ experience (control group). The target laboratory Hb value was set to >8 g/dL at postoperative day 1 (POD1). The primary endpoints were the product of total time and degree of SpHb <8 g/dL (area under SpHb 8 g/dL) during the period up to POD1 and the incidence of laboratory Hb <8 g/dL at POD1. The secondary endpoints were the amount of blood transfusion and inappropriate blood transfusion, which was defined as allogeneic blood transfusion unnecessary in a case of SpHb >12 g/dL or delayed transfusion in a case of SpHb <8 g/dL.

Results

The area under SpHb 8 g/dL was 37.6 ± 44.1 g/dL-min (5 patients) in the control group and none in the SpHb group (P = .0281). There was 1 patient with Hb <8 g/dL at POD1 in the control group. There was no difference in laboratory Hb levels and the amount of blood transfusion. Forty-one patients (19 in the control group and 22 in the SpHb group) received an allogeneic blood transfusion. Among these patients, 7 in the control group and none in the SpHb group received inappropriate blood transfusion (P = .0022).

Discussion

The SpHb monitoring could reduce unnoticed anemia, which may prevent complications and be useful in avoiding unnecessary and excessive blood transfusion.

Conclusion

Postoperative SpHb monitoring decreased the incidence of transient, unnoticed anemia during the period up to POD1 and inappropriate blood transfusion.

Impact of Perioperative Blood Transfusion in Anemic Patients Undergoing Infra Inguinal Bypass

OBJECTIVE

Patients who present with lower extremity ischemia are frequently anemic and the optimal transfusion threshold for this cohort remains controversial. We sought to evaluate the impact of blood transfusion on postoperative major adverse cardiac events (MACE), including myocardial infarction, dysrhythmia, stroke, congestive heart failure, and 30-day mortality for these patients.

METHODS

All consecutive patients who underwent infra-inguinal bypass at our institution from 2011 to 2020 were included. Perioperative red blood cell transfusion was the primary exposure, and the primary outcome was MACE. Univariate and multivariable analyses were performed to assess the impact of patient and procedural variables, including red blood cell transfusion, stratified by hemoglobin (Hgb) nadir: <7, 7-8, and >8 g/dL.

RESULTS

Of the 287 patients reviewed for analysis, 146 (50.9%) had a perioperative transfusion (mean: 1.6 ± 3 units). Patients who received a transfusion had a mean nadir Hgb of 8.3 ± 1.0 g/dL, compared to 10.1 ± 1.7 g/dL without a transfusion. The overall incidence of MACE was 15.7% (45 of 287 patients). Univariate analysis demonstrated that MACE was associated with blood transfusion (P = 0.009), lower Hgb nadir (P = 0.02), and higher blood loss (P = 0.003). On multivariate analysis, transfusion was independently associated with MACE for patients with a Hgb nadir >8 g/dL (OR: 3.09; P = 0.006), but not for patients with Hgb nadir 7-8 g/dL (OR: 0.818; P = 0.77). Additionally, patients with MACE had significantly longer length of hospital stay than for patients without (13 vs. 7.7 days, P = 0.001).

CONCLUSIONS

For patients undergoing infra-inguinal bypass, receiving a red blood cell transfusion with a Hgb nadir >8 g/dL was associated with a 3-fold increase in MACE, with nearly twice the length of stay. For patients with a Hgb 7-8 g/dL, transfusion did not increase or reduce the incidence of MACE. These findings suggest no benefit of blood transfusion for patients with Hgb nadir >7 g/dL and harm for Hgb >8 g/dL, however causation cannot be proven due to the retrospective nature of the study and randomized studies are needed to confirm or refute these findings.

A Theoretically Informed Approach to Support the Implementation of Pre-Operative Anemia and Iron Deficiency Screening, Evaluation, and Management Pathways: Protocol for a Type Two Hybrid-Effectiveness Study

Introduction

Blood transfusions are a risk factor for increased morbidity, mortality, and length of hospital stay. Patient blood management guidelines provide guidance to reduce risk and improve patient outcomes. They outline steps to help prevent transfusions and considerations for when deciding to transfuse. One recommendation to prevent unnecessary transfusion is to optimize patients using Pre-operative Anemia and Iron Deficiency Screening, Evaluation and Management Pathways (PAIDSEM-P). The uptake of these recommendations is highly variable, and an effective approach to implementing them in a tailored and context-specific manner remains elusive.

Method and Design

A mixed-methods, interventional study, using a type two-hybrid effectiveness-implementation design, will evaluate the impact of a change package to improve the uptake of PAIDSEM-P. The change package consists of the intervention (PAIDSEM-P) supported by theoretically informed implementation strategies. Pre- and post-implementation, retrospective health record reviews will determine the effect of the change package on provider outcomes, including compliance with guideline recommendations as measured by the proportion of patients who have the appropriate tests performed, and, if required, appropriate treatment and/or referrals. Patient outcomes will be measured by checking for any difference in the proportion of patients with anemia on the day of surgery and the proportion of patients who receive a blood transfusion during the peri-operative period. An economic evaluation will be conducted to compare health outcomes and costs. The feasibility, acceptability and appropriateness of the PAIDSEM-P will be assessed using a quantitative, validated survey to measure implementation outcomes.

Discussion

Testing of implementation theory is required to advance understanding of what works, in what context, and the impact on implementation success. This study aims to evaluate the impact of a theoretically informed change package on improving the uptake of PAIDSEM-P. If successful, it will also provide a framework for health care facilities to follow when addressing other evidence-practice gaps.

Development and validation of a nomogram to predict intraoperative blood transfusion for gastric cancer surgery

OBJECTIVE

To construct and validate a nomogram composed of preoperative variables to predict intraoperative blood transfusion for gastric cancer surgery.

BACKGROUND

Intraoperative transfusion for gastric cancer surgery is a common medical procedure that is associated with increased postoperative complications.

METHODS

A total of 999 patients who underwent gastrectomy between January 2010 and June 2019 were randomly allocated into the primary and validation cohorts in a 2:1 ratio. In the primary cohort, logistic analyses were performed to identify independent predictors for transfusion. Using the Akaike information criterion, selected variables were incorporated to construct a nomogram. Validations of the nomogram were performed in the primary and validation cohorts. The discrimination ability of the nomogram was assessed by the concordance index (C-index), and calibration was assessed by calibration curves and the Hosmer-Lemeshow goodness-of-fit test.

RESULTS

The following risk factors for transfusion were identified and used to construct the nomogram: ASA status (III-IV vs I-II: odds ratio [OR] 1.74), comorbidities (yes vs no: OR 1.57), tumour location (diffuse vs lower: OR 4.05), cTNM stage (III vs I: OR 1.95), and a preoperative haemoglobin level less than 80 g/L (vs over 120 g/L: OR 35.30). The C-index was 0.859 and 0.850 in the primary and validation cohorts, respectively, which both indicated good discrimination of the nomogram. Additionally, both calibration curves and Hosmer-Lemeshow tests (p-value 0.184 and 0.887, respectively) demonstrated high agreement between the predictions and actual outcomes.

CONCLUSION

A nomogram composed of preoperative variables to predict blood transfusion for gastric cancer surgery was effectively developed and validated. This nomogram could be used to improve the utilisation of red blood cells for gastrectomy.

The prevalence of pre-operative anaemia and an examination of its effect on transfusion practice between sexes: A multicentre retrospective study

Pre-operative anaemia affects one third of patients presenting for surgery and is associated with increased peri-operative morbidity and mortality. Most studies on this subject make a distinction in acceptable haemoglobin level between sexes. We analysed data for patients undergoing major elective surgery, with pre-operative anaemia defined as haemoglobin <13 g/dL. Data was collected for 1074 patients, of whom 411 (38.3%) had pre-operative anaemia. The odds of red cell transfusion were significantly higher in patients with pre-operative anaemia, OR = 4.35 [95%CI OR: 3.0- 6.2]. Additional binary logistic regression results identified haemoglobin level, male gender and increasing age as independent predictors for red cell transfusion. The length of post-operative stay was also significantly higher in anaemic patients, those with lower haemoglobin, males and older patients. Women were twice as likely to have a haemoglobin < 13 g/dl as men. Women were also 3.55 times more likely not to be transfused despite being anaemic. This suggests differences in clinician's attitudes to transfusion limits in women, despite Blaudszun et al. 2018 showing that women with borderline anaemia (Hb 12-12.9 g/dL) are: more likely to be transfused; to be transfused more units of red cells; and to have longer lengths of hospital stay than non- anaemic women. A change in attitude to acceptable haemoglobin in women is needed. Increased clinician awareness of the associated morbidity of even a mild reduction in haemoglobin in women is required to result in more pro-active anaemia management pre-operatively and less allogenic red cell transfusion, shorter lengths of hospital stay and overall decreased morbidity.

Role of preoperative intravenous iron therapy to correct anemia before major surgery: a systematic review and meta-analysis

BACKGROUND

Preoperative anemia is a common comorbidity that often necessitates allogeneic blood transfusion (ABT). As there is a risk associated with blood transfusions, preoperative intravenous iron (IV) has been proposed to increase the hemoglobin to reduce perioperative transfusion; however, randomized controlled trials (RCT) investigating this efficacy for IV iron are small, limited, and inconclusive. Consequently, a meta-analysis that pools these studies may provide new and clinically useful information.

METHODS/DESIGN

Databases of MEDLINE, EMBASE, EBM Reviews; Cochrane-controlled trial registry; Scopus; registries of health technology assessment and clinical trials; Web of Science; ProQuest Dissertations and Theses; Clinicaltrials.gov; and Conference Proceedings Citation Index-Science (CPCI-S) were searched. Also, we screened all the retrieved reference lists.

SELECTION CRITERIA

Titles and abstracts were screened for relevance (i.e., relevant, irrelevant, or potentially relevant). Then, we screened full texts of those citations identified as potentially applicable.

RESULTS

Our search found 3195 citations and ten RCTs (1039 participants) that met our inclusion criteria. Preoperative IV iron supplementation significantly decreases ABT by 16% (risk ratio (RR): 0.84, 95% confidence interval [CI]: 0.71, 0.99, p = 0.04). In addition, preoperatively, hemoglobin levels increased after receiving IV iron (mean difference [MD] between the study groups: 7.15 g/L, 95% CI: 2.26, 12.04 g/L, p = 0.004) and at follow-up >  4 weeks postoperatively (MD: 6.46 g/L, 95% CI: 3.10, 9.81, p = 0.0002). Iron injection was not associated with increased incidence of non-serious or serious adverse effects across groups (RR: 1.13, 95% CI: 0.78, 1.65, p = 0.52) and (RR: 0.96, 95% CI: 0.44, 2.10, p = 0.92) respectively.

CONCLUSIONS

With moderate certainty, due to the high risk of bias in some studies in one or two domains, we found intravenous iron supplementation is associated with a significant decrease in the blood transfusions rate, and modest hemoglobin concentrations rise when injected pre-surgery compared with placebo or oral iron supplementation. However, further full-scale randomized controlled trials with robust methodology are required. In particular, the safety, quality of life, and cost-effectiveness of different intravenous iron preparations require further evaluation.