Contents lists available at ScienceDirect European Journal of Internal Medicine journal homepage: www.elsevier.com/locate/ejim Review Article The essence of frailty: A systematic review and qualitative synthesis on frailty concepts and definitions Ulrike Junius-Walker a, ⁎ , Graziano Onder b , Dagmar Soleymani c , Birgitt Wiese a , Olatz Albaina d , Roberto Bernabei b , Emanuele Marzetti b , on behalf of ADVANTAGE JA WP4 group 1 a Institute of General Practice, Hannover Medical School, Carl-Neuberg Str. 1, 30625 Hannover, Germany b Department of Geriatrics, Neurosciences and Orthopaedics, Teaching Hospital “Agostino Gemelli”, L.go A. Gemelli 8, 00168 Rome, Italy c Santé publique France, 14 rue du Val d'Osne, 94140 Saint-Maurice, France d Association Centre of International Excellence on Research in Chronicity (Kronikgune), Bilbao Exhibition Centre, Ronda de Azkue 1, Barakaldo 48902, Basque Country, Spain ARTICLE INFO Keywords: Frail elderly Public health Health policy Qualitative methods ABSTRACT 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. 1. Introduction Frailty is regarded as a health condition of decreased functional reserves leading to a vulnerable state with the inherent risks of a multitude of adverse outcomes. These include, but are not limited to, disability, increased health care use, and premature death [1]. As a considerable and growing share of older people qualify to be labelled as frail, the condition has become a major concern for ageing societies and their health care systems [2]. On the one hand, frailty interferes with the way old people like to live and feel, on the other hand, it sub- stantially adds to the rise of health care costs [3]. Therefore, appropriate diagnostic and therapeutic strategies are needed to coun- teract frailty and to impede the occurrence of its negative health-related outcomes. An ineluctable requisite for efficiently managing frailty is a common understanding of what frailty is. Unfortunately, a consensus on the definition and concept of frailty has not yet been reached [4]. This uncertainty is rooted in the intrinsic characteristics of frailty. Indeed, the condition can neither be classified as a corollary of the ageing process nor as a disease. It is heterogeneous in its manifestation and defies clinical staging, e.g., clear definition of onset. These character- istics indicate that frailty does not fit into the traditional medical mind- https://doi.org/10.1016/j.ejim.2018.04.023 Received 28 March 2018; Received in revised form 25 April 2018; Accepted 27 April 2018 ⁎ Corresponding author. 1 Under acknowledgement all the names are of the group are listed. E-mail addresses: junius-walker.ulrike@mh-hannover.de (U. Junius-Walker), graziano.onder@unicatt.it (G. Onder), dagmar.soleymani@santepubliquefrance.fr (D. Soleymani), wiese.birgitt@mh-hannover.de (B. Wiese), oalbaina@kronikgune.org (O. Albaina), roberto.bernabei@unicatt.it (R. Bernabei), emanuele.marzetti@policlinicogemelli.it (E. Marzetti). European Journal of Internal Medicine xxx (xxxx) xxx–xxx 0953-6205/ © 2018 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved. Please cite this article as: Ulrike, J.-W., European Journal of Internal Medicine (2018), https://doi.org/10.1016/j.ejim.2018.04.023