This article presents a contemporary snapshot of preoperative intravenous iron use in our hospital and data about associated patient outcomes. In this series of elective general surgical and colorectal patients, 43% of patients presenting for surgery were anaemic preoperatively. This is in line with prevalence reported elsewhere. Just over one third of our anaemic patients received a course of intravenous iron. This study is not restricted to tightly vetted trial participants, exclusion criteria or study protocols. While the ‘real world’ nature of this data may be considered beneficial, it also presents several challenges in drawing meaningful conclusions.
In our data, there is a marked difference in the male-to-female ratios of patients between the anaemic and non-anaemic groups, with females being over-represented in the anaemic group. This may be explained by the universal Hb threshold of 130 g/l used to define anaemia. This threshold is based on the AAGBI consensus statement – a change from more traditional practice of accepting a lower threshold in female patients, considering that women are just as likely to bleed similar amounts as their male counterparts and may even start with a lower circulating volume. This difference in male-to-female split observed here, however, may affect outcomes between the groups studied.
When comparing anaemic patients who received intravenous iron and those who did not, it is important to note that those who received intravenous iron had a lower mean starting haemoglobin. This may indicate differing characteristics between the groups such as comorbidity or frailty, and suggests that those who received intravenous iron were starting from a worse baseline health status. This, however, was not reflected in their ASA classification as there was a higher proportion of ASA 3 patients within the cohort who did not receive intravenous iron. Other differing characteristics, not captured within this data, may also have influenced decision making. While this makes it difficult to assess the impact of the intervention, it is reassuring to see that the outcomes between cohorts are similar.
Decision making around offering intravenous iron was at the discretion of the treating clinician. Where intravenous iron was not offered to a patient with IDA, the reason for this was not recorded. In addition to this, the CoVID-19 pandemic has presented significant challenges to maintaining services, with limited access to theatres and the redeployment of preoperative nurses to wards. This likely will have affected patient selection for surgery, decision making and prioritisation. Details regarding such external factors have not been recorded but will almost certainly have influenced outcomes. No immediately pre-surgery haemoglobin data are available for the group who didn’t receive intravenous iron, and so an assumption was made that their haemoglobin had remained stable in between the preoperative assessment clinic and the day of surgery – this of course may not have been the case, particularly in those with colorectal cancer.
The recently published PREVENTT trial suggested that administering a standard dose of intravenous iron in the 10 days prior to major open surgery had no effect on risk of blood transfusion or mortality, although there was an indication that it may reduce readmissions to hospital. The PREVENTT study protocol poorly reflects our local practice. In the PREVENTT trial, laparoscopic surgery was excluded, the dose of iron was limited to a single standardised dose; severely anaemic patients were excluded and in many cases the participant’s iron status was unknown.
Locally, our pathway offers individualised doses of intravenous iron to patients with proven iron deficiency anaemia of any severity presenting for open or laparoscopic surgery. This may mean that our intervention is better targeted to those patients who stand to receive the most benefit. Despite this, we did not observe any difference in the rates of blood transfusion, hospital length of stay, unplanned critical care admission or readmission to hospital following discharge in patients with IDA who received intravenous iron.
The use of intravenous iron was associated with a Hb increment in our patients. While we have failed to demonstrate significant outcome benefits of using preoperative intravenous iron in our analysis, there are too many potential confounders in our data to say why this was the case. It may also be that our threshold haemoglobin of 130 g/l is too high for this intervention. It is clear from Fig. 1 that those with a lower starting haemoglobin showed the best Hb response to intravenous iron.
Despite this, we strongly believe that we should continue to identify and treat IDA preoperatively, unless significant high quality evidence to the contrary is presented. As with any other medical comorbidity, our aim is to optimise our patients preoperatively. Investigating and treating IDA is considered an example of good medicine – indeed, in our centre we have referred several patients for investigation of IDA aetiology, with some revealing new diagnoses which have significantly altered their management. When compared with blood transfusion, intravenous iron is a safe and relatively cheap intervention. Aside from outcomes relating to blood transfusion, intravenous iron has been shown to improve quality of life indicators, which probably reflects the ubiquitous role of iron in physiology. In a recently published follow-up of the IVICA trial examining IDA in colorectal cancer, clinically significant improvements in multiple quality of life domains were observed following iron administration. It would be interesting to know if similar improvements were experienced by our patients.