The essence of frailty: A systematic review and qualitative synthesis on frailty concepts and definitions.

Background: One of the major threats looming over the growing older population is frailty. It is a distinctive health state characterised by increased vulnerability to internal and external stressors. Although the presence of frailty is well acknowledged, its concept and operationalisation are hampered by the extraordinary phenotypical and biological complexity. Yet, a widely accepted conception is needed to offer tailored policies and approaches. The ADVANTAGE Group aims to analyse the diverse frailty concepts to uncover the essence of frailty as a basis for a shared understanding.

Method: A systematic literature review was performed on frailty concepts and definitions from 2010 onwards. Eligible publications were reviewed using concept analysis that led to the extraction of text data for the themes "definition", "attributes", "antecedents", "consequences", and "related concepts". Qualitative description was used to further analyse the extracted text passages, leading to inductively developed categories on the essence of frailty.

Results: 78 publications were included in the review, and 996 relevant text passages were extracted for analysis. Five components constituted a comprehensive definition: vulnerability, genesis, features, characteristics, and adverse outcomes. Each component is described in more detail by a set of defining and explanatory criteria. An underlying functional perspective of health or its impairments is most compatible with the entity of frailty.

Discussion: The recent findings facilitate a focus on the relevant building blocks that define frailty. They point to the commonalities of the diverse frailty concepts and definitions. Based on these components, a widely accepted broad definition of frailty comes into range.