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 .
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 .