Identification and management of preoperative anaemia in adults: A British Society for Haematology Guideline update

The previous version of this guideline was published in 2015¹ and provided a comprehensive review of the available literature. Since then, a number of key clinical trials have reported findings relevant to the investigation and management of preoperative anaemia including those considering optimal dosing of oral iron^2, 3 and the use of intravenous iron for patients undergoing major surgery.^4, 5

The SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) pandemic has placed extra importance on the appropriate management of preoperative patients, with a now huge number of patients⁶ awaiting elective surgical procedures postponed by the pandemic. All UK nations have published recovery plans, which outline actions that will be undertaken to address the care backlog, including those affecting elective surgery.^7-10 A BSH Good Practice Paper published in 2021¹¹ made recommendations for best patient blood management (PBM) while working within the limitations imposed by the need to minimise hospital attendances to reduce the risk of SARS-CoV-2 infection. Many of the recommendations made at that time remain relevant and where appropriate have been incorporated into the current guideline.

While blood stocks are currently good, the blood supply has been challenging, with NHS Blood and Transplant declaring an Amber alert in October 2022.¹² This unprecedented event led to a rapid push to implement PBM wherever possible to reduce demand for blood. Managing the demand for blood in elective surgical patients by appropriately identifying and managing anaemia in the preoperative setting is therefore important not only at an individual patient level but also at a system-wide level to ensure blood is available for all who need it.

This updated guideline is cognisant of the role of Primary Care in the management of these patients, and this is reflected in the writing group membership as well as the recommendations made. The guideline writing group is pleased to have representation from all four UK nations to ensure this guidance is widely applicable. It sits alongside the recently published Centre for Perioperative Care guideline for the management of anaemia in the perioperative pathway.¹³ This BSH guideline provides an up-to-date literature review with recommendations. Implementation should be informed by local circumstances and integrated into exiting care pathways.

The association of preoperative anaemia with patient outcome after surgery

Anaemia is associated with an increased likelihood of requiring transfusion, as well as mortality and morbidity after major surgery. Preoperative anaemia is also, in principle, modifiable with appropriate treatment though it is unclear under what circumstances such modification translates to patient benefit. Definitions of PBM have evolved over the years since its inception, with the recent publication of a global definition as follows: ‘PBM is a patient-centred, systematic, evidence-based approach to improve patient outcomes by managing and preserving a patient's own blood, while promoting patient safety and empowerment’.¹⁴ Preoperative anaemia diagnosis and management therefore falls under the PBM umbrella. Patients requiring surgical intervention who present with anaemia are more likely to receive a transfusion of packed red cells. Preoperative anaemia and blood transfusion have been associated with increased morbidity and mortality as shown by several systematic reviews and observational studies.^15-17 Studies reviewing the prevalence of anaemia in the preoperative population vary but demonstrate up to 35%–50% of preoperative patients to be anaemic,^18-20 this being influenced by the presenting disease, that is, cancer population, the burden of comorbidities, age, gender and surgical procedure.

The severity of anaemia has also been linked to outcomes.¹⁶ Patients with a haemoglobin (Hb) concentration >100 g/L, classified as mildly anaemic, had a 30% increased relative risk of complications and death.

The identification of links between preoperative anaemia and adverse outcomes has led to further investigation by perioperative care teams into the causes of anaemia in the surgical patient. Hung et al. demonstrated by bone marrow sampling of anaemic patients presenting for cardiac surgery that most (80%) were iron deficient.²¹ This figure was corroborated in patients undergoing major abdominal surgery in the PREVENTT study where 82% had iron deficiency.²² Recent perioperative guidelines suggest identifying and managing the underlying cause of anaemia is essential in its management.¹³ Transfusing a patient for haematinic deficiencies without a significant symptom burden to justify it exposes patients to unnecessary risks associated with transfusion such as transfusion reactions, fluid overload, incorrect component transfusions and, more rarely, infection.²³ Transfusion for haematinic deficiency in the absence of symptoms is therefore reportable to Serious Hazards of Transfusion (SHOT) as an avoidable transfusion.²⁴ Transfusing without correcting the haematinic deficiency also leaves the patient at risk of the adverse effects of the deficiency itself and a relapse of the anaemia as the transfused red cells senesce.