Linking Frailty Instruments to the International Classification of Functioning, Disability, and Health: A Systematic Review

To date, the major dilemma concerning frailty is the lack of a standardized language regarding its operationalization. Considering the demographic challenge that the world is facing, standardization of frailty identification is indeed the first step in tackling the burdensome consequences of frailty. To demonstrate this diversity in frailty assessment, the available frailty instruments have been linked to the International Classification of Functioning, Disability, and Health (ICF): a standardized and hierarchically coded language developed by World Health Organization regarding health conditions and their positive (functioning) and negative (disability) consequences. A systematic review on frailty instruments was carried out in PubMed, Web of Knowledge, and PsycINFO. The items of the identified frailty instruments were then linked to the ICF codes. 79 original or adapted frailty instruments were identified and categorized into single (n = 25) and multidomain (n = 54) groups. Only 5 frailty instruments (indexes) were linked to all 5 ICF components. Whereas the ICF components Body Functions and Activities and Participation were frequently linked to the frailty instruments, Body Structures, Environmental and Personal factors were sparingly represented mainly in the multidomain frailty instruments. This review highlights the heterogeneity in frailty operationalization. Environmental and personal factors should be given more thought in future frailty assessments. Being unambiguous, structured, and neutral, the ICF language allows comparing observations made with different frailty instruments. In conclusion, this systematic overview and ICF translation can be a cornerstone for future standardization of frailty assessment.