Cross-sectoral inter-rater reliability of the clinical frailty scale – a Danish translation and validation study

Background Focus on frailty status has become increasingly important when determining care plans within and across health care sectors. A standardized frailty measure applicable for both primary and secondary health care sectors is needed to provide a common reference point. The aim of this study was to translate the Clinical Frailty Scale (CFS) into Danish (CFS-DK) and test inter-rater reliability for key health care professionals in the primary and secondary sectors using the CFS-DK. Methods The Clinical Frailty Scale was translated into Danish using the ISPOR principles for translation and cultural adaptation that included forward and back translation, review by the original developer, and cognitive debriefing. For the validation exercise, 40 participants were asked to rate 15 clinical case vignettes using the CFS-DK. The raters were distributed across several health care professions: primary care physicians ( n = 10), community nurses (n = 10), hospital doctors from internal medicine ( n = 10) and intensive care ( n = 10). Inter-rater reliability was assessed using intraclass correlation coefficients (ICC), and sensitivity analysis was performed using multilevel random effects linear regression. Results The Clinical Frailty Scale was translated and culturally adapted into Danish and is presented in this paper in its final form. Inter-rater reliability in the four professional groups ranged from ICC 0.81 to 0.90. Sensitivity analysis showed no significant impact of professional group or length of clinical experience. The health care professionals considered the CFS-DK to be relevant for their own area of work and for cross-sectoral collaboration. Conclusion The Clinical Frailty Scale was translated and culturally adapted into Danish. The inter-rater reliability was high in all four groups of health care professionals involved in cross-sectoral collaborations. However, the use of case vignettes may reduce the generalizability of the reliability findings to real-life settings. The CFS has the potential to serve as a common reference tool when treating and rehabilitating older patients.