Introduction

Perioperative anaemia is a frequent finding among patients undergoing major surgical intervention. In the major surgery population, preoperative anaemia is particularly prevalent, affecting an estimated 20-40% of patients, and is established as a potent, independent risk factor for adverse clinical outcomes [1]. In response, standardised strategies for preoperative haemoglobin (Hb) optimisation, such as patient blood management (PBM) pathways, have been widely integrated into clinical practice [2]. However, a significant proportion of patients continue to experience profound postoperative anaemia due to patient comorbidities, the high-risk nature of vascular procedures, and intraoperative blood loss, which preoperative optimisation strategies alone cannot fully mitigate [1].

While preoperative anaemia is a significant concern, postoperative anaemia is ubiquitous, with a prevalence up to 90% following major surgery according to World Health Organisation (WHO) criteria [1,3]. Historically, postoperative anaemia has been dismissed as an inevitable physiologic sequela of surgical trauma rather than a distinct, modifiable clinical condition [2,3]. Consequently, its independent prognostic significance has remained poorly defined compared to its preoperative counterpart. However, emerging evidence suggests that a depleted postoperative Hb mass may drive a cascade of adverse short-term outcomes, including prolonged hospitalisation, increased susceptibility to sepsis, higher readmission rates, and elevated mortality [1,4].

In vascular surgery, both the clinical impact of postoperative anaemia depth and the effectiveness of targeted postoperative management strategies remain insufficiently characterised and limited in the literature, as existing studies have focused predominantly on preoperative optimisation or on general surgical cohorts, leaving this high-risk subspecialty underrepresented in the literature.

Aim and hypothesis

The primary aim was to evaluate the association between the severity of postoperative anaemia and the incidence of short-term adverse outcomes, defined as a composite of prolonged hospital stay (seven or more days), 30-day readmission, and 30-day mortality among adult patients undergoing inpatient vascular surgical procedures at a UK tertiary referral centre.

The secondary aims were twofold: first, to assess the comparative predictive utility of postoperative anaemia severity against preoperative and persistent perioperative anaemia models; and second, to explore whether the strength of these prognostic associations varies across patient gender, composite comorbidities, or surgical approaches (open vs. minimally invasive interventions).

We hypothesised that postoperative anaemia severity would demonstrate a significant dose-dependent relationship with adverse outcomes and provide superior predictive accuracy to preoperative or persistent anaemia models alone.