Frailty is a complex multisystem disorder associated with aging and poor functional reserve[1]. Frailty can be assessed clinically using several validated scoring systems, such as the Clinical Frailty Scale (CFS), which allows clinicians to apply a numeric score to a subjective report of a patient's functional state [2]. The CFS has been widely adopted in non-surgical specialties as a method of triaging patients to appropriate frailty services, however its use in surgical specialties remains heterogenous. The American Society of Anaesthesiology (ASA) score is widely used in surgical patients as a marker of fitness for surgical intervention and is largely based on assessment of physiological state and prior comorbidities. To date, composite scores incorporating functional and physiological states along with comorbidities have not been applied to vascular surgical populations. Frailty is known to be prevalent in vascular surgical populations, and is a risk factor for inferior outcome[3]. Studies assessing frailty in CLTI populations are largely retrospective, making accurate assessment of frailty challenging due to the subjective assessment of function required. This study aims to describe the prognostic value of CFS in a prospective cohort of patients presenting with CLTI, and to propose a composite prognostic score incorporating function and comorbidity.

This single centre study prospectively consecutive patients presenting acutely to a tertiary vascular surgical centre over a 12-month period. CFS was scored on admission, and baseline clinical characteristics recorded. Patients with CFS >4 were defined as frail, and patients with ASA > 2 were defined as high-risk. The primary outcome was all-cause mortality during the follow-up period. The effect of baseline parameters on survival was assessed using Kaplan-Meier analyses and Cox proportional hazards models. Covariates with p <0.10 on univariate analysis were incorporated into a multivariate backwards conditional model with the threshold for stepwise removal set at p <0.10. A novel score, the CFS-ASA score (0-2) was derived from subgroups of CFS>4 and ASA >2, with each being assigned an integer value which was then incorporated into the combined score. Statistical analyses were performed using IBM SPSS v28.0.

There were 249 patients included in this study of which 133 (53.4%) had a CFS > 4 and 202 (81.1%) had ASA>2. The mean (SD) age was 72.8 (11.3) years and 73 patients (29.6%) were over the age of 80. The median (IQR) follow-up time was 16.0 (5.0) months, and there were 93 deaths (37.3% mortality) during the follow-up period. The mean (95% CI) overall survival for the CFS > 4 cohort was 13.8 (11.8 - 15.7) months compared with 22.0 (20.3 - 23.6) months for the CFS ≤ 4 cohort (p < 0.001) (figure 1). Patients in the CFS > 4 cohort had a higher 30-day mortality (16.7% vs. 2.9%, p <0.001). On the multivariate backwards conditional model, CFS > 4 (HR 2.56, 95% CI 1.47 - 4.45, p < 0.001), Age > 80 (HR 2.11, 95% CI 1.37 - 3.26, p < 0.01), Diabetes (HR 0.60, 95% CI 0.39 - 0.93, p < 0.05), prior CVA (HR 1.85, 95% CI 1.16 - 2.96, p < 0.01), and Albumin <32 g/L (HR 2.40, 95% CI 1.52 - 3.79, p < 0.001) were significantly associated with mortality. Regarding the composite CFS-ASA score, there were 28 (11.9%) patients with CFS-ASA = 0, 81 (34.5%) patients with CFS-ASA = 1, and 126 (53.6%) patients with CFS-ASA = 2. Mean (95% CI) survival in the CFS-ASA 0 vs. 1 vs. 2 was 23.6 (21.0 - 26.2) vs. 20.8 (18.8- 22.9) vs. 13.7 (11.8 - 15.7) months (p < 0.001) (figure 2). Increasing CFS-ASA score was associated with inferior survival on univariate analysis (HR 2.84, 95% CI 1.89 - 4.26, p < 0.001). Patients with CFS > 4 and ASA >2 had significantly inferior survival compared to patients with CFS ≤ 4 and ASA ≤ 2 (p < 0.001) (table 1).

Frailty is endemic in CLTI populations and is an important risk factor for inferior early and mid-term outcomes. The CFS is a reproducible, reliable scoring system which can be effectively applied to CLTI patients. Composite scoring systems which combine comorbidities and functional state may offer superior prognostic value to existing scores in isolation. Assessment and management of frailty is an important strategy for patient selection and risk mitigation.

[1] Q. L. Xue, "The Frailty Syndrome: Definition and Natural History," Clin. Geriatr. Med., vol. 27, no. 1, p. 1, Feb. 2011. [2] K. Rockwood et al., "A global clinical measure of fitness and frailty in elderly people.," CMAJ, vol. 173, no. 5, pp. 489-95, Aug. 2005. [3] J. S. M. Houghton et al., "Frailty Factors and Outcomes in Vascular Surgery Patients: A Systematic Review and Meta-analysis," Ann. Surg., vol. 272, no. 2, pp. 266-276, Aug. 2020.