Table 4 Definition of frailty

General definition

Frailty is a multidimensional geriatric syndrome characterized by an increased vulnerability and a loss of adaptability to stress. This state is characterized by an increased risk of adverse outcomes, such as falls, delirium, disability, and mortality [55, 57, 71]. Two main models allow to assess the frailty status of patients: Fried’s phenotype model and Rockwood’s cumulative deficit model.

Fried’s phenotype model

A frailty phenotype is based on the five following features:

• Unintentional weight loss

• Self-reported exhaustion

• Low energy expenditure

• Slow gait speed

• Weak grip strength

Patients with none of these features are considered as not frail (or robust), those with one or two as pre-frail, and those with three or more as frail [13].

Rockwood’s cumulative deficit model

Frailty is defined as an accumulation of defined individual deficits, where the more of these deficits a person has, the higher the probability that this person is frail. Accordingly, a “frailty index” can be calculated from the addition of relevant age-related health variables such as symptoms, signs, abnormal laboratory values, disease states, and disabilities [72].