Reliability and validity of a frailty assessment tool in specialized burn care, a retrospective multicentre cohort study

Frailty is a predictor of adverse outcomes in elderly patients. The Canadian Study of Health and Aging Clinical Frailty Scale (CFS) is an often-used frailty assessment instrument. However, the CFS’s reliability and validity in patients with burn injuries are unknown. This study aimed to assess the CFS’s inter-rater reliability and validity (predictive validity, known group validity and convergent validity) in patients with burn injuries treated to specialized burn care. A retrospective multicentre cohort study was conducted in all three Dutch burn centres. Patients aged ≥ 50 years with burn injuries, with a primary admission in 2015–2018, were included. Based on information in the electronic patient files, a research team member scored the CFS retrospectively. Inter-rater reliability was calculated using Krippendorff’s α. Validity was assessed using logistic regression analysis. Patients with a CFS ≥ 5 were considered frail. In total, 540 patients were included, with a mean age of 65.8 years (SD 11.5) and a Total Body Surface Area (TBSA) burned of 8.5%. The CFS was used to assess frailty in 540 patients and the reliability of the CFS was scored for 212 patients. Mean CFS was 3.4(SD 2.0). Inter-rater reliability was adequate, Krippendorff’s α 0.69 (95%CI 0.62–0.74). A positive frailty screening was predictive of a non-home discharge location (OR 3.57, 95%CI 2.16–5.93), a higher in-hospital mortality rate (OR 1.06–8.77), and a higher mortality rate within 12 months after discharge (OR 4.61, 95%CI 1.99–10.65) after adjustment for age, TBSA, and inhalation injury. Frail patients were more likely to be older (for