Kihon Checklist validation in patients with rheumatoid arthritis: Italian translation, cross-cultural adaptation, and evaluation of the validity in comparison to two frailty screening tools based on the Fried phenotype and deficit accumulation model

Objectives: To compare the diagnostic test accuracy in terms of discriminant validity of the Kihon Checklist (KCL), Italian version, with respect to the Comprehensive Rheumatologic Assessment of Frailty (CRAF), and the Survey of Health, Ageing and Retirement in Europe Frailty Instrument (SHARE-FI) in identifying the presence of frailty in rheumatoid arthritis (RA) patients. Methods: An Italian version of the KCL was obtained by a consensus of experts. Then, adult RA patients underwent a cross-sectional evaluation inclusive of KCL, CRAF, and SHARE-FI. The performance of the tools was determined in terms of differences in areas under the receiver operating characteristic curves (AUC-ROCs) considering the Cardiovascular Health Study (CHS) criteria has external gold standard. For KCL, the optimal cut-point was determined at the Youden index. Results: The study included 219 RA patients. The three tools provided varying frailty prevalence percentages, from 16.0% (SHARE-FI) to 35.6% (CRAF). No scale performed better than others, according to AUC-ROCs comparisons, and when compared to the CHS criteria, all scales have an accuracy rate >80%. A KCL cut-off point of 7 resulted the optimum trade-off for sensitivity (93.3%), specificity (90.8%), with a positive likelihood ratio of 10.15. Conclusions: All the tools examined were useful and reflected the definition of frailty, however, the KCL was the most suitable since it is self-administered and might enable interventions in RA patients.