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Iron Infusion

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Ross Hanrahan

Perioperative Anaemia

Pre-operative anaemia is associated with significantly increased perioperative risk.  A 2015 meta-analysis1 found pre-operative anaemia to be associated with increased mortality (OR 2.9), acute kidney injury (OR 3.75) and infection (OR 1.93).  In contrast to studies in cardiac surgery2,3 and critical care4 patients, non-cardiac surgery patients may benefit from higher haemoglobin targets5, but exact haemoglobin targets are still unclear.

Perioperative Iron Infusion

A 2019 Cochrane review6 including 372 patients found that pre-operative iron did not result in reduced need for blood transfusion.  Nevertheless, encouraging evidence from smaller trials7 has promoted widespread adoption of pre-operative iron.

A systematic review and meta-analysis in 20218 found that pre-operative iron decreased rates of blood transfusion by 16%, as summarised in the below diagram.

Forest plot showing pooled comparison effect of Intravenous iron therapy versus placebo / standard of care on the proportion of the transfused patients.

 

At odds with these findings,The PREVENTT Trial9,10 (2020) randomized 487 anaemic patients scheduled for major elective open abdominal surgery to placebo or 1g Ferrinject a median of 15 days pre-operatively.  Patients randomized to iron achieved higher haemoglobins (mean difference 4.7g) by the day of surgery, but the difference lost statistical significance in the days immediately post-operatively.  IV iron receiving patients did achieve higher haemoglobin levels again though, at 8 weeks and 6 months post-operatively.

There was no difference in transfusion rate or 30 day mortality between the two study arms, nor any reduction of transfusion rate out to 6 months post op.  Subgroup analysis of patients with iron deficiency11 demonstrated iron deficient patients responded better to iron (as expected) but still no reduction in 30 day transfusion rate.

Interestingly, readmissions to hospital in the 8 weeks following surgery were significantly lower in the group receiving IV iron (13% vs 22%), with the commonest reasons for readmission listed as general post-operative complications, (11% vs 15%), general infections (3 vs 3%) and wound infections (<1% vs 3%).

Mean Haemoglobin concentrations in patients by treatment group (PREVENTT).

Bars indicate 95% Confidence intervals

Overall, recent 2023 consensus recommendations from the International Consensus Conference on Anemia Management in Surgical Patients12 (ICCAMS) advise that Iron therapy should be administered as treatment for pre-operative iron deficient anaemia (except when contra-indicated) and that IV iron is preferable to oral iron in this setting.

The CPOC Guideline for Management of Anaemia in the Perioperative Pathway (Sept 2022) suggests oral iron if surgery is at least 4 weeks away, and IV iron or post-ponement of surgery if surgery is within 4 weeks. 

13

References

  1. Meta-analysis of the association between preoperative anaemia and mortality after surgery - BJS 2015
  2. Effects of restrictive red blood cell transfusion on the prognoses of adult patients undergoing cardiac surgery - a meta-analysis of randomized controlled trials - Critical Care 2018
  3. Restrictive or Liberal Red-Cell Transfusion for Cardiac Surgery - TRICS III - NEJM 2017
  4. A Multicentre, randomized, controlled clinical trial of transfusion requirements in Critical Care- TRICC - NEJM 1999
  5. Liberal transfusion strategy improves survival in perioperative but not in crtically ill patients - a meta-analysis of randomised trials - BJA 2015
  6. Iron therapy for preoperative anaemia - Cochrane 2019
  7. The Important Role for Intravenous Iron in Perioperative Patient Blood Management in Major Abdominal Surgery - Annals of Surgery 2016
  8. Role or Preoperative IV Iron Therapy to Correct Anemia Before Major Surgery - Systematic Review and Meta-Analysis - 2021
  9. Preoperative intravenous iron to treat anaemia before major abdominal surgery - PREVENTT - Lancet 2020
  10. The PREVENNT randomised, double-blind, controlled trial of preoperative intravenous iron to treat anaemia before major abdominal surgery - an independent discussion - BJA 2021
  11. The Association Between Iron Deficiency and Outcomes - a Secondary Analysis of the Intravenous iron Therapy to Treat Iron Deficient Anaemia in Patients Undergoing Major Abdominal Surgery - 2023
  12. Recommendations From the International Consensus Conference on Anemia Management in Surgical Patients (ICCAMS) - 2023
  13. The Important Role for Intravenous Iron in Perioperative Patient Blood Management in Major Abdominal Surgery - Annals of Surgery 2016
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