POSTVenTT RCT - Post-operative variability in anaemia treatment: a pilot randomised controlled trial.

Anaemia affects nearly a quarter of the world, and is common in surgical patients with a third of patients presenting with preoperative anaemia and three quarters of patients discharged from hospital with anaemia. The World Health Organisation defines anaemia as an insufficient circulating red cell mass, with a haemoglobin (Hb) concentration of < 130 g.l-1 for men and < 120 g.l-1 for women. Peri-operative anaemia is associated with increased postoperative complications and delayed patient recovery leading to increased post-operative morbidity and mortality. Anaemia also leads to an increased use of allogenic blood transfusions, which is an independent risk for poorer patient outcomes. The most common cause of preoperative anaemia is iron deficiency, which can be caused by reduced or impaired dietary iron absorption, chronic blood loss, or disruption of normal iron metabolism due to co-morbidities or inflammation, aetiologies commonly seen in patients undergoing major abdominal surgery, which causes an increase in hepcidin production resulting in functional iron deficiency, and reduced red cell production. Surgical anaemia can be due to chronic disease, blood loss at operation or secondary to surgical inflammation. Cytokines (particularly IL-6) upregulate hepcidin, the master regulator of iron homeostasis, which prevents iron transport leading to failure of dietary iron absorption, and sequestration of iron within macrophages. This leads to functional iron deficiency and subsequently anaemia of chronic disease. The efficacy of intravenous iron therapy may be impacted by the balance between the inflammatory modulation of iron sequestration and bone marrow suppression with the hypoxic drive for erythrogenesis. Although efficacy of intravenous iron was shown in the IRONMAN trial - performed in patients following ICU admission - and the PREVENTT trial in preoperative patients, the one size all approach may not be precise. Consequently, in the surgical pathway, the optimal timing and modality is unknown. The outcome of this research will provide evidence on the efficacy of post-operative iron administration to treat anaemia in surgical patients. The study will also provide feasibility data to help support a larger future trial.