Preoperative Anemia Treatment With Intravenous Iron in Patients Undergoing Major Orthopedic Surgery: A Systematic Review

Outcomes of perioperative intravenous iron infusion in femoral fracture surgery: A systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Patient blood management recommends the use of intravenous (IV) iron infusion to reduce inappropriate blood transfusion perioperatively for anaemic surgical patients. However, evidence regarding its use in urgent femoral fracture surgery is limited. This systematic review aims to collate the current evidence regarding the utilisation of IV iron in femoral fracture surgery.

METHOD

MEDLINE, Embase, Cochrane CENTRAL, Clinicaltrials.gov, and the WHO ICTRP databases were systematically searched for randomised controlled trials (RCT) comparing the outcomes of perioperative IV iron infusion with placebo in adults requiring surgical management for femoral fractures. Risk ratios (RR) were calculated using the Mantel-Haenszel method for dichotomous outcomes, and mean differences (MD) were calculated with the inverse-variance method for continuous outcomes.

RESULTS

Six RCTs with 1292 patients were included. No statistically significant difference was found in the proportion of patients receiving red blood cell (RBC) transfusion (RR = 0.87, 95%CI: 0.75; 1.01, p = 0.058) between groups. Statistically significant difference in postoperative haemoglobin concentration was found between groups measured between day 4-7 of admission (MD = 1.93 g/L, 95%CI: 0.48; 3.39, p = 0.024), but not clinically significant. No statistically significant differences were found between groups in mortality rate, length of hospital stay, infection rate, or return to home rate.

CONCLUSION

Current evidence indicates that IV iron infusion alone does not provide any clinically significant benefit in femoral fracture surgery. Further high-quality RCTs are needed to explore its synergistic potential when used in combination with other perioperative optimisation methods, including tranexamic acid, erythropoietin and cell salvage.

Effect of Preoperative Recombinant Human Erythropoietin on the Need for Blood Transfusion and Surgical Outcomes in Adult Patients Undergoing Cardiac Surgery: A Systematic Review and Meta-Analysis with Trial Sequential Analysis

This study aimed to examine the value of preoperative recombinant human erythropoietin (rhEPO) administration to adults undergoing elective cardiac surgery. Databases were searched for randomized controlled trials (RCTs) comparing rhEPO plus standard treatment versus standard treatment only. Primary outcomes were the need for and volume of homologous blood transfusion (HBT). Secondary outcomes were the lengths of intensive care unit (ICU) and hospital stay and the incidence of major adverse events. There was very low certainty that rhEPO is associated with a reduction in the need for HBT, with a number needed to treat of 5.6 (95% confidence interval [CI], 3.9-12.5), and low certainty that it is associated with a moderate reduction in HBT volume (Hedges g = -0.55; 95% CI, -0.79 to -0.32). Meta-regression revealed that studies with a higher proportion of females or older patients demonstrated less benefit of rhEPO in terms of reduced consumption of HBT. Trial sequential analysis showed that rhEPO was superior to standard treatment only for reducing the need for and volume of HBT. Regarding secondary outcomes, there was moderate certainty that rhEPO is associated with a limited reduction in the length of ICU (Hedges g = -0.10; 95% CI, -0.19 to -0.01) and hospital stay (Hedges g = -0.13; 95% CI = -0.25 to -0.02), and low certainty for increased risk of myocardial infarction, with a number needed to harm of 36.1 (95% CI, 17.9-127.4). More well-designed, adequately powered RCTs are needed to draw conclusions regarding the value of rhEPO.

Postoperative intravenous iron to treat iron-deficiency anaemia in patients undergoing cardiac surgery: a protocol for a pilot, multicentre, placebo-controlled randomized trial (the POAM trial)

Background

Iron-deficiency anaemia, occurring in 30-40% of patients undergoing cardiac surgery, is an independent risk factor for adverse outcomes. Our long-term goal is to assess if postoperative i.v. iron therapy improves clinical outcomes in patients with preoperative iron-deficiency anaemia undergoing cardiac surgery. Before conducting a definitive RCT, we first propose a multicentre pilot trial to establish the feasibility of the definitive trial.

Methods

This internal pilot, double-blinded, RCT will include three centres. Sixty adults with preoperative iron-deficiency anaemia undergoing non-emergency cardiac surgery will be randomised on postoperative day 2 or 3 to receive either blinded i.v. iron (1000 mg ferric derisomaltose) or placebo. Six weeks after surgery, patients who remain iron deficient will receive a second blinded dose of i.v. iron according to their assigned treatment arm. Patients will be followed for 12 months. Clinical practice will not be otherwise modified. For the pilot study, feasibility will be assessed through rates of enrolment, protocol deviations, and loss to follow up. For the definitive study, the primary outcome will be the number of days alive and out of hospital at 90 days after surgery.

Ethics and dissemination

The trial has been approved by the University Health Network Research Ethics Board (REB # 22-5685; approved by Clinical Trials Ontario funding on 22 December 2023) and will be conducted in accordance with the Declaration of Helsinki, Good Clinical Practices guidelines, and regulatory requirements.

Clinical trial registration

NCT06287619.

Relationship between preoperative hemoglobin levels and length of stay in elderly patients with hip fractures: A retrospective cohort study

Globally, hip fractures in elderly individuals are a prevalent and serious issue. Patients typically have a longer length of stay (LOS), which increases the risk of complications and increases hospitalization costs. Hemoglobin (Hb) is a routine blood test that is associated with disease prognosis. This study aimed to investigate the relationship between preoperative Hb and LOS in elderly hip fracture patients and to determine a reliable transfusion threshold. The clinical data of hip fracture patients (aged ≥ 60 years) admitted to the Department of Orthopaedics, Shenzhen Second People's Hospital, between January 2012 and December 2021 were retrospectively analyzed. Multiple linear regression analysis was used to assess the linear relationship between preoperative Hb and LOS. Smooth curve fitting was performed to investigate potential nonlinear relationships. In the case of discovering nonlinear relationships, a weighted two-piecewise linear regression model was built, and the inflection points were determined using a recursive algorithm. Subgroup analyses were conducted based on age and gender. A total of 1444 patients with an average age of (77.54 ± 8.73) years were enrolled. After adjusting for covariates, a nonlinear relationship was found between preoperative Hb and LOS. The two-piecewise linear regression model revealed an inflection point of 10 g/dL. On the left of the inflection point (Hb < 10 g/dL), the LOS was reduced by 0.735 days for every 1 g/dL increase in Hb (β = -0.735, 95% confidence interval: -1.346 to -0.124, P = .019). On the right side of the inflection point (Hb > 10 g/dL), the relationship was not statistically significant (β = 0.001, 95% confidence interval: -0.293 to 0.296, P = .992). In elderly hip fracture patients, there is a nonlinear association between preoperative Hb and LOS. However, when Hb levels were <10 g/dL, there was a negative correlation with the LOS. No correlation was observed when Hb levels were >10 g/dL. These findings underscore the importance of timely intervention to manage Hb levels in elderly patients with hip fractures, potentially reducing hospitalization durations and associated complications.

Increasing severity of preoperative anemia is associated with higher postoperative medical and surgical complications after primary shoulder arthroplasty

BACKGROUND

Anemia is a major cause of morbidity worldwide and compounds numerous medical conditions. Studies have found associations between anemia and both medical and surgical complications after shoulder arthroplasty (SA); however, most of these studies have used commercially available national databases with limited information on outcomes and typically short-term follow-up. Our study sought to evaluate the midterm outcomes of primary SA at a single institution when stratified by the degree of preoperative anemia.

METHODS

Between 2000 and 2020, 5231 primary SA (477 hemiarthroplasties, 2091 anatomic total SA, and 2335 reverse SA) with preoperative hematocrit values available and a minimum follow-up of 2 years were collected from a single-institution joint registry database. The severity of anemia was subclassified as no anemia (hematocrit >39% for males, >36% for females; n = 4194 [80.2%]), mild anemia (hematocrit 33%-39% for males, 33%-36% for females; n = 742 [14.2%]), and moderate-to-severe anemia (hematocrit <33% for both males and females; n = 295 [5.6%]). The mean follow-up time for the entire cohort was 5.9 years (range, 2-22 years). Medical and surgical complications, reoperations, revisions, and implant survivorship were assessed.

RESULTS

SA with moderate-to-severe anemia had the highest rate of nonfatal and nontransfusion medical complications (5.1%) relative to the nonanemic (1.2%; P < .001) and mild anemic groups (1.5%; P < .001). Similarly, SA with moderate-to-severe anemia had the highest rate of surgical complications (19.3%) compared with mild anemia (14.3%; P = .044) and no anemia (11.6%; P < .001). Postoperative transfusion was most frequent in the moderate-to-severe anemia cohort (40.3%) compared with the mild anemia (14.2%; P < .001) and nonanemic groups (2.5%; P < .001). Furthermore, SA who received postoperative transfusions had a higher risk of nonfatal medical complications (8.2% vs. 1.0%; P < .001), 90-day mortality (1.5% vs. 0.03%; P = .001), and surgical complications (19.5% vs. 12.0%; P < .001) when compared with those without transfusion.

CONCLUSIONS

Moderate-to-severe anemia (hematocrit <33% for both males and females) was identified in approximately 5.6% of patients who underwent SA at a single institution and was associated with increased medical and surgical complications. Patients who received postoperative transfusions presented elevated rates of medical complications, 90-day mortality, and surgical complications. Health care teams should be aware of these risks in order to provide more individualized medical optimization and postoperative monitoring.

Effects of intraoperative or postoperative administration of intravenous iron supplements on hemoglobin recovery in patients with total knee arthroplasty: A systematic review and meta-analysis

BACKGROUND

The objectives of the researchers are as follows: First, to investigate whether intraoperative or postoperative administration of Intravenous (IV) iron supplements in patients undergoing primary total knee arthroplasty (TKA) can contribute to the hemoglobin recovery during the postoperative period (between 4 and 8 weeks after surgery). Second, to examine whether the administration of IV iron supplements during or immediately after TKA in patients undergoing primary TKA can reduce the need for allogenic blood transfusion during hospitalization.

METHODS

Articles published between January 1, 1990, and June 30, 2023 were searched in PubMed, Cochrane, and Embase. The population, intervention, comparison, and outcome of this study are as follows; Population: Patients undergoing primary total knee arthroplasty; Intervention: Administration of IV iron supplements during or immediately after surgery; Comparison: Non-administration of IV iron supplements; Outcome: Degree of hemoglobin recovery (between 4 and 8 weeks after surgery) and the need for blood transfusion during hospitalization.

RESULTS

There was a statistically significant difference in the amount of change in hemoglobin between iron supplementation group and non-iron supplementation group. The effect size were -0.44 (95% confidence interval: -0.69 to -0.19, P value < .001) in all patients. This means that the amount of change in hemoglobin were significantly reduced in the iron supplementation group than in the non-iron supplementation group. There was a statistically significant difference for post-operative transfusion rate between 2 groups. The effect size were 0.28 (95% confidence interval: 0.10-0.81, P value = .02) in all patients. This means that the post-operative transfusion rate was significantly less in the iron supplementation group than in the non-iron supplementation group.

CONCLUSION

The administration of IV iron supplements during or after TKA surgery increases hemoglobin recovery between 4 and 8 weeks after surgery and reduces the need for allogeneic blood transfusion during hospitalization.

Interventions for reducing red blood cell transfusion in adults undergoing hip fracture surgery: an overview of systematic reviews

BACKGROUND

Following hip fracture, people sustain an acute blood loss caused by the injury and subsequent surgery. Because the majority of hip fractures occur in older adults, blood loss may be compounded by pre-existing anaemia. Allogenic blood transfusions (ABT) may be given before, during, and after surgery to correct chronic anaemia or acute blood loss. However, there is uncertainty about the benefit-risk ratio for ABT. This is a potentially scarce resource, with availability of blood products sometimes uncertain. Other strategies from Patient Blood Management may prevent or minimise blood loss and avoid administration of ABT.

OBJECTIVES

To summarise the evidence from Cochrane Reviews and other systematic reviews of randomised or quasi-randomised trials evaluating the effects of pharmacological and non-pharmacological interventions, administered perioperatively, on reducing blood loss, anaemia, and the need for ABT in adults undergoing hip fracture surgery.

METHODS

In January 2022, we searched the Cochrane Library, MEDLINE, Embase, and five other databases for systematic reviews of randomised controlled trials (RCTs) of interventions given to prevent or minimise blood loss, treat the effects of anaemia, and reduce the need for ABT, in adults undergoing hip fracture surgery. We searched for pharmacological interventions (fibrinogen, factor VIIa and factor XIII, desmopressin, antifibrinolytics, fibrin and non-fibrin sealants and glue, agents to reverse the effects of anticoagulants, erythropoiesis agents, iron, vitamin B12, and folate replacement therapy) and non-pharmacological interventions (surgical approaches to reduce or manage blood loss, intraoperative cell salvage and autologous blood transfusion, temperature management, and oxygen therapy). We used Cochrane methodology, and assessed the methodological quality of included reviews using AMSTAR 2. We assessed the degree of overlap of RCTs between reviews. Because overlap was very high, we used a hierarchical approach to select reviews from which to report data; we compared the findings of selected reviews with findings from the other reviews. Outcomes were: number of people requiring ABT, volume of transfused blood (measured as units of packed red blood cells (PRC)), postoperative delirium, adverse events, activities of daily living (ADL), health-related quality of life (HRQoL), and mortality.

MAIN RESULTS

We found 26 systematic reviews including 36 RCTs (3923 participants), which only evaluated tranexamic acid and iron. We found no reviews of other pharmacological interventions or any non-pharmacological interventions. Tranexamic acid (17 reviews, 29 eligible RCTs) We selected reviews with the most recent search date, and which included data for the most outcomes. The methodological quality of these reviews was low. However, the findings were largely consistent across reviews. One review included 24 RCTs, with participants who had internal fixation or arthroplasty for different types of hip fracture. Tranexamic acid was given intravenously or topically during the perioperative period. In this review, based on a control group risk of 451 people per 1000, 194 fewer people per 1000 probably require ABT after receiving tranexamic acid (risk ratio (RR) 0.56, 95% confidence interval (CI) 0.46 to 0.68; 21 studies, 2148 participants; moderate-certainty evidence). We downgraded the certainty for possible publication bias. Review authors found that there was probably little or no difference in the risks of adverse events, reported as deep vein thrombosis (RR 1.16, 95% CI 0.74 to 1.81; 22 studies), pulmonary embolism (RR 1.01, 95% CI 0.36 to 2.86; 9 studies), myocardial infarction (RR 1.00, 95% CI 0.23 to 4.33; 8 studies), cerebrovascular accident (RR 1.45, 95% CI 0.56 to 3.70; 8 studies), or death (RR 1.01, 95% CI 0.70 to 1.46; 10 studies). We judged evidence from these outcomes to be moderate certainty, downgraded for imprecision. Another review, with a similarly broad inclusion criteria, included 10 studies, and found that tranexamic acid probably reduces the volume of transfused PRC (0.53 fewer units, 95% CI 0.27 to 0.80; 7 studies, 813 participants; moderate-certainty evidence). We downgraded the certainty because of unexplained high levels of statistical heterogeneity. No reviews reported outcomes of postoperative delirium, ADL, or HRQoL. Iron (9 reviews, 7 eligible RCTs) Whilst all reviews included studies in hip fracture populations, most also included other surgical populations. The most current, direct evidence was reported in two RCTs, with 403 participants with hip fracture; iron was given intravenously, starting preoperatively. This review did not include evidence for iron with erythropoietin. The methodological quality of this review was low. In this review, there was low-certainty evidence from two studies (403 participants) that there may be little or no difference according to whether intravenous iron was given in: the number of people who required ABT (RR 0.90, 95% CI 0.73 to 1.11), the volume of transfused blood (MD -0.07 units of PRC, 95% CI -0.31 to 0.17), infection (RR 0.99, 95% CI 0.55 to 1.80), or mortality within 30 days (RR 1.06, 95% CI 0.53 to 2.13). There may be little or no difference in delirium (25 events in the iron group compared to 26 events in control group; 1 study, 303 participants; low-certainty evidence). We are very unsure whether there was any difference in HRQoL, since it was reported without an effect estimate. The findings were largely consistent across reviews. We downgraded the evidence for imprecision, because studies included few participants, and the wide CIs indicated possible benefit and harm. No reviews reported outcomes of cognitive dysfunction, ADL, or HRQoL.

AUTHORS' CONCLUSIONS

Tranexamic acid probably reduces the need for ABT in adults undergoing hip fracture surgery, and there is probably little or no difference in adverse events. For iron, there may be little or no difference in overall clinical effects, but this finding is limited by evidence from only a few small studies. Reviews of these treatments did not adequately include patient-reported outcome measures (PROMS), and evidence for their effectiveness remains incomplete. We were unable to effectively explore the impact of timing and route of administration between reviews. A lack of systematic reviews for other types of pharmacological or any non-pharmacological interventions to reduce the need for ABT indicates a need for further evidence syntheses to explore this. Methodologically sound evidence syntheses should include PROMS within four months of surgery.

Impact of postoperative intravenous iron therapy on postoperative infections in older patients with severe anaemia after hip fracture surgery

BACKGROUND

Anaemia is common following hip fracture in ortho-geriatric patients and is associated with postoperative infections.. This study investigated whether intravenous iron supplements reduced the rate of postoperative infections within 30 days postoperatively in older adults after hip fracture surgery.

METHODS

This observational study included 198 ortho-geriatric patients July 2018-May 2020. In May 2019 a local guideline was implemented and recommended II therapy on the 3^rd postoperative day if haemoglobin concentration was < 6.5 mmol/L after hip fracture surgery.

RESULTS

The patients were divided into four treatment groups: blood transfusion (n = 44), IV iron (n = 69), blood transfusion + IV iron (n = 35) and no treatment (n = 50). The number of patients who had an infection within 30 days was similar in the two time periods (38.8% before vs. 38.9% after systematic I.V. iron supplementation, P = 1.00) and no significant difference according to risk of infection was found between treatment groups.

CONCLUSION

This study documents no effect of intravenous iron supplements on postoperative infections in older adults after hip fracture surgery.

TRIAL REGISTRATION

The study was registered with the Danish Data Protection Authority (2008-58-0028) the 2^th of September 2019.

Anemia and formation of deep vein thrombosis before operation in patients with knee osteoarthritis: a cross-sectional study

BACKGROUND

Preoperative anemia is a common complication in knee osteoarthritis (KOA) patients. However, the association between anemia and preoperative deep vein thrombosis (DVT) in osteoarthritis patients remains unknown. The aim of this study was to investigate such association.

METHODS

In this retrospective study, we included 1005 KOA patients undergoing total knee arthroplasty (TKA) in our hospital. According to preoperative hemoglobin levels, the patients were divided into anemia group and non-anemia group. According to the results of Doppler ultrasonography for the lower extremities, the patients were divided into DVT group and non-DVT group. A logistic model was established through propensity score matching (PSM), with anemia before TKA as the dependent variable, DVT-related variable as the covariate, and 0.03 as the Caliper value. The anemia group and non-anemia group were matched at a 1:1 ratio and 310 successfully matched. After matching, logistic regression analysis was used to evaluate the correlation between preoperative anemia and DVT in KOA patients.

RESULTS

In this study, 342 cases (33.6%) had preoperative anemia and 73 cases (7.2%) had DVT before TKA. After matching, 46 DVT cases (7.42%) were found. By using binary logistic regression after PSM, we found that the risk for preoperative DVT formation in TKA patients with preoperative anemia increased by 1.97 times [95% (CI 1.05-3.69)], P = 0.035.

CONCLUSION

Preoperative anemia is considered as an independent risk factor for the formation of preoperative DVT in KOA patients.

TRIAL REGISTRATION

ChiCRT2100054844.

CONTEMPORARY RECOMMENDATIONS ON PATIENT BLOOD MANAGEMENT IN JOINT ARTHROPLASTY

Hip and knee replacement surgery are a common and effective procedure for the relief of pain and loss of function. The number of procedures is increasing and great interest is given how to improve outcome following hip and knee replacement surgery. Last two decades have been characterized by many innovations in hip and knee replacement surgery including minimally invasive technique but also by improvements in anesthetic technique and blood management. The patients undergoing hip and knee replacement surgery are commonly elderly and have cos-existing organ dysfunctions. These procedures are characterized by great perioperative disturbances including cardiovascular complications, high incidence of thromboembolic complications, possible significant perioperative blood loss, possible bone cement effect and high level of postoperative pain. Anesthetic assessment of patients include preoperative preparations, intraoperative and postoperative care. In this article, all problems of perioperative blood management are discussed. The recent data of advantages of blood management for every patient are outlined. Blood management include preoperative preparation, use of autologous blood in perioperative period and administration of drugs for minimizing intraoperative blood loss. The final result of improvements in blood management is reducing in blood loss and need for allogeneic blood and significant reduction in perioperative morbidity.

Unexplained anemia of aging: Etiology, health consequences, and diagnostic criteria

BACKGROUND

Up to 15% of people aged 60 and over are anemic, and the prevalence of anemia increases with age. In older men and women, anemia is associated with increases in the risk of death and all-cause hospitalization, poor functional capacity, quality of life, and depression.

METHODS AND RESULTS

We reviewed the literature describing anemia in aging populations, focusing on the specific diagnostic criteria of anemia and potential causes in older men and women. Even after extensive etiologic workup that involves careful medical history, physical examination, laboratory measurements, and additional studies such as bone marrow biopsy, anemia of aging is unexplained in up to 40% of older patients with anemia. As a result, treatment options remain limited.

CONCLUSIONS

The prevalence of unexplained anemia of aging (UAA; also called unexplained anemia of the elderly, UAE), its deleterious impacts on health, physical function, and quality of life, and the lack of effective treatment or therapy guidelines represent a compelling unmet clinical need. In this review and consensus document, we discuss the scope of the problem, possible causes of UAA, diagnostic criteria, and potential treatment options. Because even mild anemia is strongly linked to poor clinical outcomes, it should receive clinical attention rather than simply being considered a normal part of aging.

Cerebral Hypoxia: Its Role in Age-Related Chronic and Acute Cognitive Dysfunction

Postoperative cognitive dysfunction (POCD) has been reported with widely varying frequency but appears to be strongly associated with aging. Outside of the surgical arena, chronic and acute cerebral hypoxia may exist as a result of respiratory, cardiovascular, or anemic conditions. Hypoxia has been extensively implicated in cognitive impairment. Furthermore, disease states associated with hypoxia both accompany and progress with aging. Perioperative cerebral hypoxia is likely underdiagnosed, and its contribution to POCD is underappreciated. Herein, we discuss the various disease processes and forms in which hypoxia may contribute to POCD. Furthermore, we outline hypoxia-related mechanisms, such as hypoxia-inducible factor activation, cerebral ischemia, cerebrovascular reserve, excitotoxicity, and neuroinflammation, which may contribute to cognitive impairment and how these mechanisms interact with aging. Finally, we discuss opportunities to prevent and manage POCD related to hypoxia.

Association between intravenous iron therapy and short-term mortality risk in older patients undergoing hip fracture surgery: an observational study

Background

Anemia is common among ortho-geriatric hip fracture patients and is associated with prolonged recovery and increased postoperative mortality rate. Intravenous iron seems to increase hemoglobin recovery and reduce the mortality rate in patients undergoing orthopedic surgeries. This study investigated the association between short-term mortality risk and intravenous iron therapy in older patients undergoing hip fracture surgery.

Methods

This observational study included 210 patients undergoing hip fracture surgery from July 2018 to May 2020. These 210 patients were alive and had a hemoglobin ≤ 6.5 mmol/L on the 3rd postoperative day. In May 2019, a local intravenous iron therapy protocol was implemented and recommended intravenous iron (Monofer©) if hemoglobin on the 3rd postoperative day was ≤ 6.5 mmol/L. According to the treatment of postoperative anemia between the 1st and 3rd day post-surgery, the patients were divided into four groups: no treatment (n=52), blood transfusion (n=38), IV Monofer (n=80), and blood transfusion and IV Monofer (n=40). Primary outcome was 30-day mortality post-surgery. The secondary outcome was the impact on hemoglobin level 14–30 days postoperatively. Multivariable Cox regression was used to estimate the 30-day mortality standardized for covariates.

Results

Of 210 patients, 17 (8.1%) died within 30 days after surgery. There was a significantly lower mortality among the patients who received IV Monofer compared to those who received no treatment (HR 0.17, 95% CI [0.03–0.93], P = 0.041). Among the 86 patients with available hemoglobin measurements within 14 to 30 days post-surgery, there was no significant difference in hemoglobin level between the various treatment groups (mean 6.6 mmol/L, P = 0.1165).

Conclusion

IV Monofer on the 3rd postoperative day in older hip fracture patients seemed to reduce 30-day mortality compared with no treatment. No significant differences in hemoglobin levels between 14 and 30 days post-surgery across treatment groups were found, although this was assessed in a subset of patients with available hemoglobin levels warranting further study.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02462-x.