Routine preoperative iron studies in adults without anaemia undergoing elective cardiac surgery are unnecessary as they do not improve surgical outcomes, Australian specialists say.

Writing in Lancet Haematology the team of surgeons, intensive care physicians and anaesthetists call for the revision of guidelines that advocate for iron studies in this setting, noting that “guidelines that base clinical decisions on the thresholds for iron deficiency on the basis that they worsen patient-centred outcomes should be contemplated.”

Lead author Associate Professor Lachlan Miles, a Staff Specialist and Deputy Head of Research in the Department of Anaesthesia at Austin Health, compared the outcomes of patients undergoing elective cardiac surgery who were iron replete (n=240; haemoglobin < 130 g/L for men and < 120 g/L for women) with iron deficient patients (n=240; serum ferritin < 100 μg/L or 100–300 μg/L if transferrin saturation < 20% or C-reactive protein >5 mg/L).

The analysis of the primary outcome of days alive and at home at postoperative day 30 showed no difference between patients who were iron replete or iron deficient (median 23·18 day vs 22·87 days respectively).

There was also no difference in the analysis of the secondary outcomes of ICU stay, readmission to hospital, health related quality of life scores, red blood cell transfusion, and postoperative complications.

“Our findings suggest that patients with iron deficiency do not have a reduction in days alive and at home at postoperative day 30 compared with patients who have a normal iron status. Routine preoperative investigation for iron deficiency in patients without anaemia undergoing elective cardiac surgery using the definitions we tested might be low-value care,” they concluded.

The implications of the findings were for: “revision of guidelines that advocate for routine preoperative iron studies in adults without anaemia undergoing elective cardiac surgery,” they concluded.

There is also a need to revisit guidelines that base clinical decisions on the thresholds for iron deficiency on the basis that they worsen patient-centred outcomes should be contemplated, they added.

An accompanying editorial suggested that ferritin levels and transferrin saturations used in the trial and by the majority of hospitals to diagnose iron deficiency might not be sufficient to diagnose iron deficiency in patients undergoing surgery, particularly in the context of inflammation.

“Current studies indicate that iron deficiency has no effect on surgical outcomes and that iron supplementation in patients with iron deficiency does not improve surgical outcomes in cardiac patients.

“The question we should consider is: are we addressing the essential outcomes of surgery or should we expand our focus regarding iron deficiency and its role during postoperative surgical recovery?” they wrote.