FRAILKT: an observational cohort study comparing frailty assessment tools in adult waitlisted kidney transplant candidates

Background The 2020 KDIGO ‘Clinical Practice Guideline on Evaluation and Management of Candidates for Kidney Transplantation’ suggests frailty is measured when assessing a candidate’s suitability to be waitlisted for a kidney transplant. However, the optimal method of frailty assessment is not clear. There are numerous frailty assessment tools, but it is uncertain if these instruments are capturing the same cohort of frail candidates or whether they are measuring different constructs. This study investigated frailty prevalence in a cohort of waitlisted kidney transplant candidates from the United Kingdom and Ireland, described factors associated with frailty and explored agreement between different frailty assessment tools. Methods FRAILKT is a single-region observational cohort study of adult waitlisted kidney transplant candidates who had transplant procedures in Northern Ireland. Frailty was assessed in all candidates using four frailty assessment tools. Correlations were analysed using Spearman’s test. Agreement between frailty classifications was analysed using Cohen’s kappa. Results 190 participants were recruited. Frailty prevalence was measured by each of the tools (14.7% by Fried Frailty Phenotype, 16.8% by Edmonton Frail Scale, 9.5% by FRAIL scale and 11.0% by Clinical Frailty Scale). Factors associated with frailty depended on the tool used to measure it. Agreement between frailty assessment tools on a candidate’s frailty status was limited. Fifty participants were classified as frail using the frailty assessment tools however only three participants were classified as frail by all four frailty instruments. Conclusions Frailty prevalence in waitlisted kidney transplant candidates varies depending on the measurement tool used. The limited agreement between assessment tools suggests that they may be capturing different constructs. Establishing the optimal tool for assessing frailty in waitlisted kidney transplant candidates remains challenging.