The Fried Phenotype model classifies an individual as frail if they meet at least three of the following five criteria [1]:
- Slow walking speed
- Poor grip strength
- Unintentional weight loss of >10 pounds in the past year
- Decreased physical activity
- Self-reported exhaustion
The Frailty Index (FI) describes frailty as the accumulation of health deficits (any symptom, disease, or abnormal laboratory findings), resulting in decreased physiological reserve. The sum of an individual's accumulated health deficits is divided by the total amount of possible health deficits within a population sample. The FI score ranges from 0.1–1.0. The higher the score, the more frail the individual.[2]