Anaemia: A risk factor for death and adverse outcomes following surgery for acute lower limb ischaemia

Acute limb ischaemia (ALI) forms a significant part of the vascular surgery workload and carries with it high rates of morbidity and mortality. Anaemia is also common amongst vascular surgical patients and has been linked with poor outcomes in some subgroups. We aimed to assess the frequency of anaemia in patients with ALI and its impact on survival and complications following revascularisation to help direct future efforts to optimise outcomes in this patient group.

A retrospective analysis of prospectively collected departmental data on patients undergoing surgical intervention for ALI between 2014 and 2018 was performed. Anaemia was defined as a pre-operative haemoglobin (Hb) of <120 g/L for women and <130 g/L for men. The primary outcome was overall survival, assessed with the Kaplan-Meier estimator, with application of Cox proportional hazard modelling to adjust for confounding covariates.

There were 158 patients who underwent treatment for ALI: 89 (56.3%) of these were non-anaemic with a mean Hb of 146 (SD = 18.4), and 69 (43.7%) were anaemic with a mean Hb of 106 (SD = 13.4). Anaemic patients had a significantly higher risk of death than their non-anaemic counterparts on univariate analysis (HR = 2.11, 95% CIs, 1.28-3.5, p = 0.0036). There was ongoing divergence in survival up to around 6 months between anaemic and non-anaemic groups. Under the Cox model, anaemia was similarly significant as a predictor of death (HR = 2.15, 95% CIs, 1.17-3.95, p = 0.013), accounting for recorded comorbidities, medication use and blood transfusion.

Anaemia is a significant and independent risk factor for death following revascularisation for ALI and can be potentially be modified. Vascular surgical centres should ensure they have robust pathways in place to identify and consider treating anaemia. There is scope for further work to assess how to best optimise a patient's levels of circulating haemoglobin.