ASSOULINE, Benjamin, et al.

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Reference

Intravenous iron supplementation after liver surgery: Impact on anemia, iron, and hepcidin levels-a randomized controlled trial

ASSOULINE, Benjamin, et al.

Abstract

Anemia is a recognized risk factor for perioperative related morbidity and mortality and is frequently reported in liver surgeries with an estimated incidence of 32%. We aim to assess the impact of intravenous iron administration in the immediate postoperative period on anemia and iron status as well as to determine the kinetics of hepcidin after liver surgery. Methods:

The HepciFer trial, a randomized controlled trial, included 50 patients undergoing liver surgery. In accordance with the randomization process, patients received either ferric carboxymaltose (15 mg/kg, maximum 1 g) or placebo 4 hours after surgery.

ASSOULINE, Benjamin, et al . Intravenous iron supplementation after liver surgery: Impact on anemia, iron, and hepcidin levels-a randomized controlled trial. Surgery , 2021, vol. 170, no. 3, p. 813-821

DOI : 10.1016/j.surg.2021.03.020 PMID : 33888314

Available at:

http://archive-ouverte.unige.ch/unige:155793

Disclaimer: layout of this document may differ from the published version.

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Liver

Intravenous iron supplementation after liver surgery: Impact on anemia, iron, and hepcidin levels d a randomized controlled trial

Benjamin Assouline, MD

^a^,^*

, Alan Benoliel, MD

^a

, Ido Zamberg, MD

^a^,^b

, David Legouis, MD

^a

, Cecile Delhumeau, MPH

^a

, Mathieu Favre, MD

^a

, Axel Andr es, MD

^c

, Christian Toso, MD

^c

, Kaveh Samii, MD

^d

, Eduardo Schiffer, MD

^a^,^b

aDivision of Anesthesiology, Department of Anesthesiology, Clinical Pharmacology, Intensive Care and Emergency Medicine, Geneva University Hospitals, Geneva, Switzerland

bFaculty of Medicine, Geneva University Hospitals, Geneva, Switzerland

cDivision of Digestive Surgery, Department of Surgery, Geneva University Hospitals, Geneva, Switzerland

dDivision of Hematology, Department of Oncology, Geneva University Hospitals, Geneva, Switzerland

a r t i c l e i n f o

Article history:

Accepted 6 March 2021 Available online 20 April 2021

a b s t r a c t

Background: Anemia is a recognized risk factor for perioperative related morbidity and mortality and is frequently reported in liver surgeries with an estimated incidence of 32%. We aim to assess the impact of intravenous iron administration in the immediate postoperative period on anemia and iron status as well as to determine the kinetics of hepcidin after liver surgery.

Methods: The HepciFer trial, a randomized controlled trial, included 50 patients undergoing liver surgery. In accordance with the randomization process, patients received either ferric carboxymaltose (15 mg/kg, maximum 1 g) or placebo 4 hours after surgery.

Results: The mean hemoglobin level, 7 days after surgery, did not differ significantly between the intervention and control group (11.1±1.8 g/dL and 10.4±1.6 g/dL, respectively) with a mean difference ofþ0.7 g/dL ([95% confidence interval,0.3 toþ1.7],P¼.173). Within patients receiving intravenous iron supplementation, none presented biological signs of functional iron deficiency. Hepcidin levels remained significantly higher during the observation period in the intervention group. Inflammatory biomarkers, red blood cells transfusion rate and hospital duration of stay were similar between groups.

Conclusion: Intravenous ferric carboxymaltose administration did not result in a signiﬁcant increase of hemoglobin levels 7 days after surgery. However, this study suggests that intravenous iron supplementation in the immediate postoperative settings prevents functional iron deﬁciency. Intravenous iron supplementation overcame the hepcidin-mediated blockade of iron absorption and should be considered as the preferred route of administration in the postoperative period.

Introduction

Anemia is recognized as a major risk factor of morbidity and mortality in the perioperative period. In the context of major surgeries, postoperative anemia is observed with an incidence of as high as 80% and exposes patients to allogeneic blood transfusions (ABT).^1,2 According to an analysis of prospective data from the National Surgical Quality Improvement Program, the estimated incidence of preoperative anemia in major liver surgery is 32%.³

Liver surgery is associated with an increased risk of perioperative hemorrhage, related to the unique structure of the liver, potential vascular dissection, or to defective coagulation associated with the underlying liver disease. The risk of hemorrhage is increased in relation to the extent, the localization and the type of liver resection.³The incidence of ABT after liver surgery is about 20%.⁴

Anemia’s causes in surgical patients are well known and often multifactorial. Among these causes, iron deficiency anemia and functional iron deficiency (FID) are common, with a reported incidence of over 40% in oncological patients.⁵Data from a large cohort from Spain showed that proactively treating iron deficiency in major arthroplasty surgery resulted in a risk adjusted reduction of postoperative ABT, infection, and mortality rates as well as shorter hospital duration of stay.⁶

*Reprint requests: Benjamin Assouline, MD, Division of Anaesthesiology, Geneva University Hospitals, Rue Gabrielle-Perret-Gentil 4, CH-1205 Geneva, Switzerland.

E-mail address:benjamin.assouline@hcuge.ch(B. Assouline);

Twitter:@IdoZamberg

Contents lists available atScienceDirect

Surgery

journal homepage:www.elsevier.com/locate/surg

https://doi.org/10.1016/j.surg.2021.03.020

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Iron restricted erythropoiesis occurs in both absolute and functional iron deﬁciency. FID is characterized by an imbalance between iron demand and serum iron that is readily available for effective erythropoiesis.⁷FID is frequently seen in chronic diseases and is associated with an elevated level of hepcidin.⁸Hepcidin, the central regulatory hormone of iron metabolism, limits circulating iron concentrations by promoting degradation of the iron exporter ferroportin in target cells. Its regulation is complex and depends on multiple factors, including inﬂammatory mediators (IL-6), serum iron levels and hypoxia.⁹However, its expression after liver surgery is not well studied yet.

After liver surgery, there are potentially 2 opposing mechanisms that could impact iron metabolism. First, systemic inﬂammatory response consecutive to surgery induces an overexpression of hepcidin and thus, limits readily available circulating iron.^8,10Sec- ondly, it can be expected that, as a result of liver resection and the consecutive decreased hepatic mass, the amount of synthesized hepcidin would decrease.

To address mentioned knowledge gaps, we aimed to assess whether intravenous iron administration in the immediate postoperative period increases hemoglobin (Hb) and hematocrit (Ht) levels 7 days after surgery. In addition, we intended to study the impact of the mentioned intervention on iron status and more speciﬁcally on functional iron deﬁciency, and to determine the kinetics of hepcidin expression after liver surgery.

Methods

Study design

The study is reported according to the recommendations of the Consolidated Standards of Reporting Trials statement. The HepciFer trial was a single-center, randomized, placebo-controlled, double- blinded clinical trial (RCT) among patients undergoing liver surgery. The protocol was approved by the institutional ethics board (protocol 15e079). The study was registered atClinicalTrials.gov (NCT02631980). A Data and Safety Monitoring Board monitored the study progress and outcomes.

Patient eligibility and enrollment

Adult patients scheduled for elective liver surgery at the Geneva University Hospitals were screened and recruited from the September 9, 2015 to August 24, 2016. Exclusion criteria were age

<18 years, pregnancy, emergency surgery, patients hospitalized in the intensive care unit, ongoing sepsis, synchronous colic surgery, immunosuppression, chronic kidney disease (estimated glomerular ﬁltration rate<30 mL/min/1.73m²as calculated using the CKD-EPI formula),¹¹known or reported allergic reaction to study’s medica- tion of choice (Ferinject, ferric carboxymaltose [FC]) and hemo- chromatosis. Detailed inclusion and exclusion criteria are listed in Supplemental Materials. All participants provided written informed consent.

Procedures

After obtaining written consent, preoperative blood tests were drawn. Anesthesiologic management was provided in accordance with a standardized institutional protocol for liver resection surgery (by laparotomy), based on current evidence-based guidelines on general anesthesia with thoracic epidural analgesia.¹²In addition to standard perioperative monitoring, invasive blood pressure was monitored using the LiDCO plus (LiDCO Ltd, Cambridge, UK).¹³ Controlled-goal directed therapy for intravenous ﬂuid

administration was applied for the duration of liver resection.¹⁴ After liver resection, goal-directed therapy using fluid challenge and dynamic parameters (stroke volume variation, pulse pressure variation) was applied for patient’s volume correction. The threshold for red blood cells transfusion was defined by a hemoglobin levels lower than 7 g/dL, according to the latest recommendations of the American Association of Blood Banks.¹⁵At the end of the procedure,fluid balance was strictly evaluated (total of fluid administered including blood transfusions, blood loss and urine output) and registered in the case-report form. The patient was then transferred to the postanesthesia care unit. Standardized blood tests (Table I) were drawn at postoperative days 1, 3, 5, and 7.

Interventions

In compliance with the randomization list, each patient received either FC (15 mg/kg, maximum 1 g) or placebo (same volume of physiologic saline) intravenously on arrival in the recovery room.

Data collection

The data collected included gender, sex, age, American Society of Anesthesiologists status, type of surgery, surgical technique, weight of the operative pieces (mg), pathology results, quantification of perioperative bleeding (mL), diuresis, fluid requirements (mL), allogenic blood transfusion, and presence or absence of postoperative infections, Dindo-Clavien classification¹⁶and the duration of hospitalization (days).

Blood samples for laboratory analyses were collected preoper- atively (baseline) and at postoperative days (POD) 1, 3, 5, and 7. The following measurements were performed:

Hematologic parameters: hemoglobin (Hb; photometry, SLS method), hematocrit (Hct), leucocyte count.

Iron status: plasma iron (Iron Gen.2, Roche), Ferritin (Ft; Tina- quant Ferritin Gen.3, Roche), Transferrin saturation and index (TSAT; Tina-quant Transferrin ver.2, Roche) and soluble Trans- ferrin Receptor (sTfR, Tina-quant Soluble Transferrin Receptor, Roche). sTfR-F index was calculated as sTfR/log (Ft).

Inﬂammatory biomarkers: C-reactive protein (CRP; C-reactive protein Gen.3, Roche), and interleukin-6 (IL-6).

Hepcidin (as well as IL-6) measurements were performed at the end of the study after last blood sample of last included patient was withdrawn. Blood samples for hepcidin and Il-6 measurements were drawn in BD Vacutainer SST II Advance tubes and centrifuged within 30 minutes after collection. Serum samples were immediately stored at 80C until analysis. Hemolytic samples were discarded and blood collection was performed again. Serum hepcidin and IL-6 levels were measured using Enzyme-Linked Immunosorbent assays following manufac- turer’s instructions: hepcidin 25 (bioactive) HS ELISA (DRG, Marburg, Germany; 50) and Human IL-6 Quantikine ELISA (R&D Systems, Inc, Minneapolis, MN).

Fibrinolysis parameters: D-dimer (automated ELISA method with Immunoanalysor Vidas3 from Biomerieux) andﬁbrinogen (chronometric test or Clauss method on Coagulometer CS5100 de Sysmex).

Anemia was defined as Hb<13g/d L or Ht<39% for men, and as Hb <12g/d/L or Ht <36% for women. Iron deficiency (ID) was defined by Ft levels<30mg/L and TSAT<0.2 (20%).

Functional iron deﬁciency (FID) was deﬁned by Ft levels>100 mg/L and TSAT<0.2 (20%).

B. Assouline et al. / Surgery 170 (2021) 813e821 814

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Health-related quality of life questionnaires

Pre- and postoperative interviews were performed in order to assess patient’s quality of life with the support of standardized quality of life (QoL) questionnaires. If patient have left the hospital prematuraly, questionnaires were sent to him on POD 15 and 30.

Outcomes

The primary outcome was the mean difference in plasma levels of Hb and Hct between the 2 groups, on POD 7. The secondary

outcomes were the mean difference, between the 2 groups, in plasma levels of hepcidin and iron status markers at POD 1, 3, 5, and 7, duration of hospitalization as well as the number of patients requiring ABT during hospitalization.

Sample size

Sample size estimations were based on existing evidence concerning liver surgery where levels of Hb in the postoperative period were assumed to be of Hb of 8 g/dL (SD¼1.95 g/dL)¹⁷with standard care. Our assumption was that with the proposed intervention, Hb Table I

Baseline characteristics for total randomized patients and by treatment group

Total Iron Placebo P value

N¼49 n¼24 n¼25

median (P25-P75) median (P25-P75) median (P25-P75)

Men,n(%) 38 (77.6) 19 (79.2) 19 (76.0) .791

BMI, kg/m² 25.5 (3.8) 25.7 (3.5) 25.3 (4.2) .759*

Age, y 66 (11) 66 (13) 65 (10) .847*

ASA score,n(%) .585

1 1 (2.0) 1 (4.2) 0 (0)

2 31 (63.3) 15 (62.5) 16 (64.0)

3 17 (34.7) 8 (33.3) 9 (36.0)

Cirrhosis,n(%) 6 (12.2) 4 (16.7) 2 (8.0) .355

Perioperative bleeding (mL) 600 (300-1,000) 600 (325-900) 700 (250-1,000) .992 Fluid administration management

Ringer acetate, mL 4507 (2,500-6,100) 4,298 (2,500-5,300) 4,597 (2,680-7,000) .857

NaCl, mL 200 (100-200) 200 (100-200) 200 (100-200) .948

Blood transfusion,n(%) 10 (20.4) 5 (20.8) 5 (20.0) .942

Surgical procedure

Hepatectomy,n(%) 25 (51.0) 11 (45.8) 14 (56.0) .477

Lobectomy,n(%) 4 (8.2) 3 (12.5) 1 (4.0) .289^y

Segmentomy,n(%) 21 (42.9) 10 (41.7) 11 (44.0) .869

Surgical technic

Laparotomy,n(%) 46 (93.9) 23 (95.8) 23 (92.0) .516^y

Laparoscopy,n(%) 1 (2.0) 0 (0) 1 (4.0) .510^y

Robotic,n(%) 2 (4.1) 1 (4.2) 1 (4.0) .745^y

Liver resection

Extent of liver resection, g 414.5 (180.5-640) 455 (122-625) 403 (187-655) .695 Weight piece removed, g 635 (204-1,458) 846 (247-1,511) 535 (122-1,023) .327

Pathology .778

Hepatocellular carcinoma 9 (18.4) 5 (20.8) 4 (16.0)

Adenocarcinoma 27 (55.1) 12 (50.0) 15 (60.0)

Others 13 (26.5) 7 (29.2) 6 (24.0)

Postoperative data

Dindo-Clavien score,n(%) .302

1 24 (49.0) 10 (41.7) 14 (56.0)

2 17 (34.7) 8 (33.3) 9 (36.0)

3a 3 (6.1) 2 (8.3) 1 (4.0)

3b 1 (2.0) 0 (0) 1 (4.0)

4a 0 (0) 0 (0) 0 (0)

4b 3 (6.1) 3 (12.5) 0 (0)

5 1 (2.0) 1 (4.2) 0 (0)

Baseline biology*

Hemoglobin, g/dL 12.9 (1.9) 13.1 (1.7) 12.7 (2.0) .496

Hematocrit, % 39.5 (5.1) 40.2 (4.6) 38.8 (5.5) .322

Hepcidin, ng/L 33.4 (31.1) 43.0 (33.9) 24.6 (26.0) .025

Ferritin,mg/L 237 (233) 268 (245) 207 (220) .238

TSAT 0.3 (0.2) 0.3 (0.2) 0.3 (0.1) .471

sTfR 3.7 (1.5) 3.3 (1.1) 4.0 (1.7) .139

sTfR-F index, % 1.9 (1.2) 1.6 (0.7) 2.1 (1.5) .144

Interleukin-6, pg/mL 2.6 (0.9 - 4.8) 2.5 (0.7 - 4.8) 2.7 (1.0 - 5.1) .638

C-reactive protein, mg/L 6.8 (10.5) 5.6 (9.6) 7.9 (11.5) .795

Leucocyte, /mL 6.6 (2.1) 6.5 (2.2) 6.6 (2.2) .726

Fibrinogen, g/L 3.5 (0.9) 3.5 (0.9) 3.4 (1.0) .496

D-dimer,mg/mL 1,175 (1,816) 1,140 (1,694) 1,209 (1,960) .384

ASA, American Society of Anesthesiologists;BMI, body mass index;sTR, soluble transferrin receptor;TSAT, transferrin saturation;Ts index, transferrin saturation index.

*Values expressed as mean and SD. Student’sttest used.

yFisher's exact test used.

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levels would rise to 10 g/dL.^18,19The estimated sample size, to show a 2 g/dL difference, 7 days after FC administration (with 95% power;

2-sided test; type I error of 5%), was 25 patients per group.

Randomization and blinding

The University Hospitals of Geneva’s pharmacy generated a computer-based randomization list with a block size of 10. The pharmacy also prepared FC or placebo (physiologic saline) stored in similar looking 250 mL opaque infusion bags, which were delivered upon arrival in the postanesthesia care unit. Assignments were kept in sealed opaque envelopes and the allocation sequence was con- cealed until the end of the study. Anesthesiologic teams in charge of the patients, as well as the investigators in charge of analysis, were kept blinded to patients’allocation.

Statistical methodology Baseline characteristics

Baseline characteristics were summarized for all included patients and according to the treatment group. Continuous variables were expressed as mean±standard deviation (SD) or as median (25the75th percentile) for non-normally distributed variables.

Categorical variables were expressed as numbers and percentages.

Primary and secondary endpoints were analyzed on an intention-to-treat basis. Additionally, the primary endpoint was analyzed on a per-protocol basis. The “last observation carried forward method” was used to replace any missing data on the primary or secondary endpoints during the follow-up period.²⁰ Primary outcomes

A crude mean difference and a 95% conﬁdence interval (95% CI) between groups was calculated for Hb (g/dL) and Hct (%) at POD 7, and a Student’sttest was used to compare the 2 treatment arms. Hb (g/dL) and Hct (%) at POD 7 also were described graphically using box plots.

Secondary endpoints

Plasma levels of hepcidin, iron status markers (ferritin, transferrin saturation index levels, transferrin coefﬁcient, and soluble transferrin receptors), IL-6, C-reactive protein, and duration of stay were described as mean±SD in each treatment group at POD 7.

Crude mean differences and 95% CI between groups were calculated and differences tested using a Student’s t test. They were graphically represented from POD 1 to 7, by treatment group using box plots.

Ancillary analyses

Postoperative complications were deﬁned using the Dindo- Clavien classiﬁcation for surgical complication and expressed as numbers and percentages in each treatment group and compared using ac²or Fisher exact test, whenever appropriate. All analysis was performed using Stata 14.1 for Windows (STATA Corp, College Station, TX).

Results

Participantsﬂow and recruitment

Fifty-seven patients were assessed for eligibility from September 9, 2015 to August 24, 2016. After exclusion of 7 patients, 50 patients were randomly assigned to receive FC (n ¼ 25) or

placebo (n ¼ 25). One patient in the intervention group was excluded after randomization due to the pathologic analysis showing no trace of liver resection (Fig 1). All patients allocated to the intervention group received the study’s drug and all patients in the control group received the placebo. No adverse events were reported in both groups during the trial period.

Baseline data

Patients from both groups did not differ regarding baseline characteristics, type of surgery, pathology analyses, incidence of cirrhosis, and postoperative complications (Table I). Within our cohort, 77.6% were men, were an average age of 66 years old, and had an American Society of Anesthesiologists score of2 in 98% of the cases. In addition, 12.2% of the patient had cirrhosis. The indi- cation for liver surgery was oncologic in 94% of the patients and laparotomy was the most used surgical technic (94%). There were no significant differences between groups regardingfluid administration, bleeding, and blood transfusions during the surgical procedure. The mean Hb and Hct levels were 12.9 g/dL±1.9 and 39.5%±5.1, respectively. Owing to one outlier value in the intervention group at baseline, the mean hepcidin level was significantly higher compared with the control group. The iron status, in- flammations markers, and coagulation parameters did not differ between groups at baseline (Table I).

Primary outcome

The mean Hb level at POD 7 did not differ signiﬁcantly between the 2 study groups in the intention to treat and per protocol analysis. The mean value in the intervention group was 11.1±1.8 g/dL and 10.4 ± 1.6 g/dL in the placebo group (crude mean difference:þ0.7 [95% CI0.3 toþ1.7],P¼.173;Table IIandFig 2).

Hematocrit level did not differ signiﬁcantly as well at POD 7 in the intention to treat analysis with a mean value of 34%±4.9% in the intervention group and 31.8% ± 4.4% in the placebo group (crude mean difference:þ2.2 [95% CI0.5 toþ4.8],P¼.107;Table II andFig 2). The per protocol analysis showed a signiﬁcant increase in HCT in the intervention groupþ2.8% ([95% CI0.1 to 5.6];P¼ .045;Table II).

Secondary outcomes

Impact of intravenous iron supplementation on hepcidin and inﬂammatory markers (IL-6 and CRP)

After iron administration, hepcidin levels were signiﬁcantly higher in the intervention group in comparison to control group at POD 7 with 60.4±42.1 ng/L versus 20.7±23.5 ng/L respectively (crude mean difference: þ39.7 ng/L [95% CI þ20.2 to þ59.1], P<.0001;Table III). The peak value and the highest estimated mean difference were reached at POD 3 in the intervention group and at POD 1 in the control group (Fig 3). The mass of resected liver, as assessed by the type of surgery (hepatectomy, lobectomy, and segmentectomy) did not seem to correlate with hepcidin levels (Supplementary Materials Appendix,Table S4). For every mg/L increase of CRP, there was a mean increase of 0.3 ng/L in hepcidin level [95% CIþ0.1 toþ0.4],P<.0001). IL-6 levels did not differ at any time point between groups; the peak value was reached in both groups at POD 1 (Fig 3).

Impact of intravenous iron supplementation on iron status markers Data concerning iron status are summarized inTable III. At POD 7, iron supplementation resulted in signiﬁcantly higher levels of Ferritin and TSAT and lower level of sTfR and sTfR-f index in the B. Assouline et al. / Surgery 170 (2021) 813e821

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intervention group (Fig 4). Functional iron deﬁciency was therefore only found in the control group.

Duration of hospital stay and ABT

Duration of hospital stay and ABT did not differ signiﬁcantly between groups at POD 7 (Table I).

Ancillary analyses

They were no statistical differences between groups regarding postoperative complications (Tables IandIII). To be noted, due to

lost to follow-up (37% at POD 30), data required for QoL questionnaires analysis was insufﬁcient.

Discussion

To our knowledge, this is thefirst randomized controlled trial to evaluate the impact of IV iron administration in the postoperative period after liver surgery on Hb levels, iron status, and hepcidin levels. Our findings suggest that IV iron supplementation did not have a significant impact on the Hb levels at POD 7,

Table II

Primary endpoints at day 7 between treatment groups

Iron Placebo Crude mean difference between

placebo and iron

P value*

N Mean (SD) N Mean (SD) Mean difference (95%CI)

ITT analysis

Hemoglobin, g/dL 24 11.1 (1.8) 25 10.4 (1.6) þ0.7 (0.3 toþ1.7) .173

Hematocrit, % 24 34.0 (4.9) 25 31.8 (4.4) þ2.2 (0.5 toþ4.8) .107

Per protocol analysis

Hemoglobin, g/dL 21 11.1 (1.9) 23 10.3 (1.5) þ0.8 (0.2 toþ1.9) .110

Hematocrit, % 21 34.1 (5.1) 22 31.2 (3.9) þ2.8 (0.1 toþ5.6) .045

ITT, intention to treat.

*Student’s t test.

Fig 1.Consolidated Standards of Reporting Trials diagram for HepciFer trial.

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although this effect might be underestimated by a short follow- up of Hb concentrations. In addition, the hypothesis used for sample size calculation might have participated in the lack of statistically significant results for the primary outcome. In fact, as post operatory mean Hb levels were significantly higher than referenced values used for sample size calculation in both groups, the expected 2 g/dL increase might have been harder to achieve. Moreover, 20% of the intervention group was excluded from the analysis due to predefined exclusion criteria: four patients presented Dindo-Clavien grade 4 complications, and 1 patient did not have any liver resected according to histologic analysis. This might have reduced the statistical power of our trial.

However, our trial provides new knowledge regarding the physiopathology of iron metabolism in the postoperative period after liver surgery. More specifically, we showed that after iron supplementation, patients who received iron supplementation did not present biological markers of functional iron deficiency at POD 7 compared with the placebo group. Hepcidin kinetics was also evaluated and allowed a better understanding of iron metabolism after IV supplementation after liver surgery. The clinical signifi- cance of those finding are 2-fold. First, recent studies linked

nonanemic iron deﬁciency (NAID) to several postoperative adverse outcomes. Second, the route of iron supplementation is still considered controversial. Hepcidin kinetics suggests that the oral route would be ineffective if given postoperatively as discussed further in the discussion.

Perioperative anemia in oncologic surgery is frequent and its reported incidence is as high as 90% in the immediate period after major surgery.^21,22Iron deficiency is a common modifiable risk factor. Therefore, diagnosis and strategy to optimize patients’iron status before surgery should be part of standard care in the preoperative period. Where no other RCT have studied the interest of IV iron supplementation in liver surgery, the benefit of IV iron supplementation in major surgery has been already described. In a recent randomized controlled trial, Froessler et al reported a significant decrease in incidence of ABT after preoperative IV iron treatment in major abdominal surgery.²³In addition, Khalafallah et al studied the impact of postoperative IV iron supplementation (FC) at POD 1 within anemic patients after major surgeries (orthopedic, gynecological, and abdominal). The latter reported a significant increase in Hb level and a significant decrease in need of ABT in favor of the FC group 1 month after surgery.²⁴Consistently, Kim et al studied the effect of IV iron administration in patients Fig 2.Box plot of hemoglobin (g/dL) and hematocrit by treatment arm at day 7.

Table III

Secondary endpoints at day 7 between treatment groups Iron Placebo

n¼24 n¼25

Mean (SD) Mean (SD) Mean difference (95% CI) P value*

Hepcidin, ng/L 60.4 (42.1) 20.7 (23.5) þ39.7 (þ20.2 toþ59.1) <.0001 Ferritin,mg/L 1,618 (889) 429 (471) þ1,189 (þ783 toþ1,595) <.0001

TSAT 0.41 (0.48) 0.14 (0.07) þ0.27 (þ0.07 toþ0.46) <.0001

sTfR, mg/L 2.8 (1.2) 4.84 (2.45) 2.02 (3.14 to0.91) <.001

sTfR-F index, % 0.89 (0.33) 2.02 (1.11) 1.13 (1.60 to0.65) <.0001

Interleukin-6, pg/mL^y 32.3 (19.962.8) 29.0 (15.747.0) NA .358

C-reactive protein, mg/L 85.7 (70.4) 65.0 (39.9) 20.7 (12.0 to 53.4) .522

Leucocyte, /mL 9.0 (3.1) 9.8 (4.7) 0.79 (3.08 toþ1.51) .912

Fibrinogen, g/L 5.2 (1.5) 5.2 (1.5) þ0.01 (0.84 toþ0.88) .881

D-dimer,mg/mL 4,703 (1,383) 4,710 (2,187) 7 (1,064 toþ1,050) .810

Duration of stay, d 16 (18) 12 (9) þ4 (4 toþ12) .399

*Wilcoxon rank-sum test or Student’sttest for mean value.

y Median (P25-P75).

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undergoing gastric surgery reporting a signiﬁcantly higher Hb levels at 3 and 12 weeks after surgery as well a subsequent sig- niﬁcant decrease in need for alternative treatment for anemia.²⁵

Knowledge gaps exist concerning the physiopathologic mechanisms involved in hepcidin expression after liver surgery with

only few published reports on the subject. Hepcidin is synthetized by the liver and is a central regulatory hormone for iron metabolism.⁸One animal trial evaluated the kinetics of hepcidin and IL-6 in mice after partial hepatectomy²⁶reporting that after 70% of liver resection, hepcidin and IL-6 levels were signiﬁcantly increased at 4

A B

C

Fig 4.Box plot of sTfR (A), TSAT (B), sTfR-f index (C) by treatment arm.

Fig 3.Box plot of hepcidin (g/dL) and interleukin-6 by treatment arm.

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and 12 hours after surgery compared with levels observed in the control group. In this trial, hepcidin levels declined to baseline values at POD1 and reached the lowest level at POD2. A similar study, conducted on human subjects, evaluating the kinetics of hepcidin in the setting of liver surgery, did not show a significant increase in hepcidin levels in the postoperative period.²⁷However, this result might be biased by the administration of IV steroid during the surgical procedure and its consecutive effect on inflammatory response. Steroids were reportedly used in mentioned study for their potential benefit on ischemia-reperfusion after liver pedicle clamping. To affirm this hypothesis, we decided to exclude from our prospective trial any patient receiving steroids or immu- nosuppressive treatment. It has been previously shown that, 24 hours after oral iron administration, hepcidin was overexpressed.²⁸ Our trial confirms these 2findings in humans. In fact, after liver surgery, hepcidin levels increased with a maximal peak at POD 1 in the control group and POD 3 in the intervention group. IL-6 levels were similar within both groups suggesting that, the delayed maximal peak of hepcidin observed in the intervention group might be due to a synergistic effect of iron supplementation and surgery related inflammatory response. Lastly, in our study, plas- matic concentrations of hepcidin seemed to vary independently of liver volume resection’s extent.

Despite the lack of significant difference in Hb levels between 2 groups at POD 7, patients who received IV iron supplementation did not show biological evidence of functional iron deficiency compared with the placebo group. This might provide more evidence for the possible beneficial effect of IV iron supplementation in liver surgery in decreasing the incidence of nonanemic iron deficiency. Iron deficiency diagnosis after surgery could be chal- lenging, as it requires dosage of several expensive biomarkers. In this context, we believe that iron deficiency should be investigated before surgery and treated regardless of patient’s Hb levels.²⁹In fact, recent studies linked NAID to several postoperative adverse outcomes. For instance, NAID was shown to be associated with an increased risk of thrombocytosis in oncologic patients,^30,31which itself is an independent risk factor for thromboembolic events.³² Moreover, NAID is independently associated with worse functional status in congestive heart failure³³and with poorer outcomes in elective cardiac surgery.³⁴

The route of iron supplementation in iron deﬁciency is a matter of debate. Our trial showed that hepcidin levels were increased in both groups in the immediate postoperative period, due to the inﬂammation induced by the surgery. In the context of hepcidin induced iron trapping within liver cells and macrophages and the subsequent decreased gastrointestinal absorption, postoperative oral iron supplementation would be therefore less effective.

Therefore, this route would not likely prevent postoperative anemia unless given weeks before surgery. Preoperative oral iron supplementation is feasible and was recently shown to be an inexpensive solution in reducing perioperative blood transfusions in colorectal surgery. Nevertheless, oral iron supplements were given daily, 3 times a day for 2 weeks before surgery where in our study a single IV dose was given which might present an advantage in term of compliance and feasibility as supplements are given in a controlled environment.³⁵In addition, oral preparations are usually poorly tolerated with gastrointestinal side effects reported in>70%

of patients in a recent meta-analysis.³⁶ Lastly, in a recent randomized controlled trial, IV iron was found to be more efficient compared with oral administration in patients with preoperative iron deficiency anemia.³⁷Our study thus gives more evidence that IV iron supplementation might be superior to the oral form and should be considered for perioperative standard care in patients presenting an iron deficiency.

Strengths of this study reside in the methodologic design, randomized-controlled, and strictly double-blinded, and in the fact that it is theﬁrst to evaluate the impact of postoperative IV intravenous supplementation in patients undergoing liver surgery on Hb, iron status and hepcidin kinetics. In addition, repetitive mea- sures of Hb, iron status and hepcidin could provide more insights on their postoperative metabolism and could help better under- stand the mechanisms involved in postoperative anemia and its prevention.

Our study’s main limitation is the timing of last blood sample collection. In fact, according to the physiology and pharmacology of IV iron supplementation, it is expected that the effect on erythropoiesis would not be reached before POD 10 to 14.^26,38,39 However, due to the usual length of hospitalization after liver surgery in our institution, most patients would have been dis- charged before POD 10 and ambulatory testing would increase chances of lost to follow-up as was conﬁrmed with the QoL analysis. Therefore, we decided to collect the last sample at POD 7.

This could have underestimated the effect of our intervention as studies on IV iron supplementation in perioperative settings showed its beneﬁcial effect only several weeks after treatment.^24,25 To be noted, we decided to administer iron postoperatively compared with the preoperative period to study iron’s metabolism and hepcidin kinetics.

Lastly, no anaphylactic reaction nor any other adverse effect which could be related to the IV iron administration, was reported in the present study. The intervention group lost 1 patient after randomization and 4 patients presented severe postoperative complications with a Dindo-Clavien score4. These patients presented the following complications: 1 acute respiratory failure due to postoperative diastolic cardiac dysfunction, 1 distributive shock due to mesenteric ischemia, 1 septic shock due to a surgical complication (biliary anastomosis leakage), and 1 acute liver failure due to portal thrombosis. There is no evidence to suggest that the occurrence of these complications in the intervention group is related to iron supplementation. Apart from the theoretical participation of iron into the oxidative stress,³⁸there is no evidence in the literature to suggest an increase incidence of sepsis with this treatment. Avni et al reported in their meta-analysis (19,253 patients), that short-term IV iron administration did not increase the risk of infection (RR 0.96; 95% CI, 0.63.1.46).⁴⁰Munoz et al, in a large observational study on short term IV iron administration and major orthopedic surgery, did not document a higher incidence of infection.⁶

In conclusion, postoperative IV iron supplementation did not result in significantly increased Hemoglobin levels 7 day after liver surgery. However, the results of this RCT provide more evidence for the role of perioperative IV supplementation in correcting functional iron deficiency. In case of deficiency, iron supplementation should be part of preoperative standard care, might be more effective if done weeks before surgery and could decrease the need for postoperative blood transfusions and nonanemic iron deficiency related adverse outcomes. In addition, IV iron supplementation might be superior to oral supplementation both due to postoperative hepcidin metabolism as well as for compliance rea- sons. Hepcidin levels in postoperative settings did not seem to be associated to the extent of liver resection and provide insights for postoperative anemia physiopathology and prevention. More research should be done in order to study the short- and long-term outcomes of iron supplementation in the perioperative settings in term of postoperative anemia, blood transfusion rates, morbidity, and mortality. In addition, more randomized-controlled trials should be done to study the effectiveness of preoperative iron supplementation with longer follow-up periods.

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Funding/Support

Study funding was provided by Vifor Pharma, Abbovie, and institutional research fund (Fonds de Service APSI-HUG No 15e01).

Conﬂict of interest/Disclosure

The authors declare no competing ﬁnancial interests. The funding organization had no role in the design and conduct of the study; collection, management, analysis and interpretation of the data. They were not consulted for the preparation, review or approval of the present manuscript.

Acknowledgments

We thank the pharmacy of the University Hospitals of Geneva (UHG) for randomizing and preparing the study drugs; the nurses from the admission and postoperative wards and the Post Anes- thesia Care Unit of the Geneva University Hospital, who cared for the patients and drew blood samples. We are particularly indebted to Oana Bulla and her team responsible for the biologic measurements in the laboratories of the Geneva University Hospital.

Supplementary materials

Supplementary material associated with this article can be found, in the online version, athttps://doi.org/10.1016/j.surg.2021.

03.020.

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