Incidence and Risk Factors for Delirium in Elderly Patients with Critical Limb Ischaemia

Delirium is associated with adverse outcomes, such as increased mortality and prolonged hospital stay. Information on the risk factors for delirium in elderly patients with critical limb ischaemia (CLI) is scarce. The aim of this study was to analyse the incidence of delirium and to identify risk factors for delirium in elderly patients undergoing surgical or endovascular treatment.

A retrospective cohort study was conducted including patients aged ≥ 65 years undergoing surgical or endovascular treatment for CLI between January 2013 and June 2018. Delirium was scored using the DOSS (Delirium Observation Screening Scale) and the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) criteria. Risk factors for delirium were analysed using logistic regression. The discriminative ability of the model was calculated using the area under the receiver operating characteristics (AUROC) curve.

In total, 392 patients were included, of which 70 (17.9%) developed delirium. Factors associated with an increased risk of delirium were: age, odds ratio (OR) 1.05 (95% confidence interval (CI) 1.0-1.1), history of femoral endarterectomy, OR 4.7 (95% CI 1.5-15), physical impairment, OR 2.2 (95% CI 1.1-4.5), history of delirium, OR 2.7 (95% CI 1.4-5.3), general anaesthesia, OR 2.6 (95% CI 1.2-5.7) and pre-operative anaemia, OR 5.9 (95% CI 2.3-15). The AUROC was .82 (95% CI 0.76-0.87, p < .001). Delirium was associated with more respiratory, renal and surgical complications, as well as a prolonged hospital stay and a more frequent discharge to a nursing home.

Delirium occurs frequently in patients with critical limb ischaemia undergoing any type of invasive treatment. This study identified multiple risk factors for delirium that may be helpful to delineate patients susceptible to its development.