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Iron Infusion

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, and some controversy persists, with a 2021 Canadian meta-analysis8 of 10 smaller RCTs suggested a 16% reduction in perioperative transfusions.

Currently the best evidence probably comes from the PREVENTT Trial.

PREVENTT Trial

The PREVENTT Trial9,10 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.

Mean Haemoglobin concentrations in patients by treatment group.

Bars indicate 95% Confidence intervals

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 deficiency (ferritin < 100ng/ml and transferrin saturation < 20%) did not alter the findings.

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%).

These findings argue against routine pre-operative administration of IV iron for anaemia for the prevention of transfusion, but raise the question of a potential benefit to recovery. Any benefit to recovery would likely be the same if IV iron is administered intra- or post-operatively, as opposed to pre-operatively, with the added benefit of reduced cost.

Ferinject Dose Calculation

via Calculosaurus

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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 of preoperative intravenous iron therapy to correct anemia before major surgery – a systematic review and meta-analysis – Systematic Reviews 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 Important Role for Intravenous Iron in Perioperative Patient Blood Management in Major Abdominal Surgery - Annals of Surgery 2016
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