The prognostic value of clinical frailty and American Society of Anesthesiology score in patients with chronic limb threatening ischaemia

Background: Frailty is a complex multisystem syndrome associated with increased comorbidity and decreased physiological reserve. There are associations between frailty and adverse outcome in surgical patients. Chronic limb threatening ischemia (CLTI) is increasingly prevalent, with a typically frail patient population. Existing frailty scoring systems focus on functional measures and do not reliably assess comorbidities. The present study aims to describe the prognostic value of multimodal frailty assessment in patients with CLTI. Patients and methods: Patients >50 years old admitted as an emergency with CLTI between May 2020 to June 2021 were included. Frailty was measured using Clinical Frailty Score (CFS), and comorbidities with American Society of Anesthiologists score (ASA). A composite score combining CFS and ASA was derived and the prognostic value compared with each component score. The primary outcome was overall survival. Results: There were 249 eligible patients, 53.4% (n=133) had CFS>4. The mean (95% CI) overall survival for the CFS>4 cohort was 15.9 (13.6-18.3) months vs. 28.5 (26.1-30.9) months for CFS similar to 4 cohort (p<0.001). Increasing CFS-ASA score was associated with inferior survival on univariate (HR=2.84, 95% CI [1.96-4.11], p<0.001) and multivariate (HR=1.78, 95% CI [1.20-2.64], p<0.01) analyses. ROC-analysis showed comparable prognostic value of CFS and CFS-ASA to predict one-year survival. Conclusions: Frailty is highly prevalent and a poor prognostic indicator in patients with CLTI admitted as an emergency. Our results suggest that incorporating assessment of comorbidities into frailty assessment may offer prognostic value, but comparable to existing clinical frailty assessment. Further work to identify patients with inferior prognosis is required.