<qa>  What is Fried index?Phenotype model: Fried et al in 2001 proposed a phenotype based model, in which she identified various clinical features that define frailty as a clinical syndrome. This criterion, known as Fried index, consists of 5 factors- shrinking, weakness, exhaustion, slowness, and low physical activity level. The Fried index is the most commonly used phenotype-based assessment tool to evaluate frailty. An advantage is its ease-of use during preoperative visits. Measurement of these factors in a perioperative setting was further characterized by Makary et al in 2010, and was the basis for the Hopkins Frailty Score HFS. 