What are the Fried Phenotype model and the Frailty Index (FI) criteria?

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    Louie Neri

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    Morgan Pfiffner, Rob Stenstrom
    Last Updated: April 23, 2025

    The Fried Phenotype model identifies frailty based on the presence of at least 3 of 5 criteria, including slow walking speed and poor grip strength. The Frailty Index quantifies frailty by calculating the ratio of an individual's accumulated health deficits to the total possible deficits; scores range from 0.1 to 1.0, and higher scores indicate greater frailty.

    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]

    What are the Fried Phenotype model and the Frailty Index (FI) criteria? - Examine