Researchers have suggested – after a rigorous medical records study covering tens of thousands of patients – that some patients with pre-operative anaemia have better outcomes if they get iron infusions before surgery rather than standard red blood cell transfusions.
Johns Hopkins Medicine researchers' findings, published in Anaesthesia & Analgesia, contribute to mounting evidence that such iron infusions, which boost the production of a person’s own red blood cells, are better than relying on someone else’s blood.
“Anaemia is incredibly common, especially in surgical patients, and until recently the default treatment has been blood transfusions before the procedure,” said Steven Frank, professor of anaesthesiology and critical care medicine at Johns Hopkins.
“However, our retrospective study showed a benefit of iron infusions over pre-operative blood transfusions in decreasing morbidity and mortality, increasing haemoglobin and decreasing the need for blood transfusions.”
The human body needs iron to make haemoglobin, the protein in red blood cells that carries oxygen to organs throughout the body.
Being anaemic is particularly concerning for patients undergoing surgery because there is almost always some amount of blood loss during any procedure. But while blood transfusions work, they also carry risks, including blood clots, hospital-acquired infections, allergic reactions and pulmonary complications, reports News-Medical.net.
It can be difficult to find a donor match if a patient has certain antibodies or a condition like sickle cell disease, for instance. As a result, physicians have long sought strategies to minimise the use of transfusions.
In the latest study, the research team used data from the TriNetX Research Network database, a global network of healthcare organisations that pool de-identified patient information. The team’s analysis used such information gathered between 2003 and 2023 on 154 358 patients over 18-years-old with a diagnosis of iron-deficient anaemia before surgery.
The data were sorted into groups of patients who were treated with iron pre-operatively but not with a blood transfusion, and patients who received a pre-operative blood transfusion but no iron infusion.
These infusions happened several weeks before a scheduled surgical procedure.
Researchers then compared post-operative complication rates including respiratory problems, kidney issues, blood clots, infections and death rates.
From this review, researchers found a 37% reduction in mortality and a 24% reduction in morbidity (complications) in patients who were treated with iron infusions compared with those treated with blood transfusions.
This finding means that patients receiving iron infusions may recover more quickly and fully from their surgical procedures without any added complications that may arise from a blood transfusion.
“The Joint Commission and the American Medical Association named blood transfusion as the number one over-used procedure in 2012. For perspective, also on the list was antibiotic use to treat the common cold,” said Frank.
“Research shows reducing blood transfusions can improve patient outcomes, and giving patients preoperative iron infusions is an easy way to do so.”
The researchers hope the new study will encourage more widespread use of pre-operative iron infusions in surgical patients. They also hope to examine whether oral iron supplements garner the same outcomes as infusions.
Study details
Propensity-matched cohort study of intravenous iron versus red cell transfusions for preoperative iron-deficiency
Una Choi, Ryan Nicholson, Steven Frank et al.
Published in Anaesthesia & Analgesia on 22 July 2024
Abstract
Background
While preoperative anaemia 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 anaemia (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 three 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 haemoglobin split into low (<7 g/dL), medium (7–<12 g/dL), and high (≥12 g/dL) to account for anaemia severity. The primary outcome was 30-day postoperative mortality with the secondary outcomes being 30-day morbidity, postoperative haemoglobin 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 haemoglobin 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 with RBC transfusion was associated with a reduction in 30-day postoperative mortality and morbidity, a higher 30-day postoperative haemoglobin 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.
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