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...