Models Definitions and Criteria of Frailty

David B. Hogan

This chapter will examine the current state of research on frailty. A number of competing and complementary models for its development will be described. This will be followed by a working definition of frailty. Finally, criteria for the identification of frailty in older individuals will be discussed. Promising future directions for research will be noted throughout the chapter. The aim is to provide useful background information about frailty for researchers interested in the field. It is an area of inquiry still early in its evolution.


In a radio broadcast on October 3, 1939, Sir Winston Churchill said about Russia that, ''It is a riddle, wrapped in a mystery, inside an enigma.'' The same can be said about frailty.

The term frail elderly is defined in the National Library of Medicine's MeSH database as ''Older adults or aged individuals who are lacking in general strength and are unusually susceptible to disease or to other infirmity.'' The concept that aging is associated with declining resiliency goes back to the dawn of western medicine, and likely, before. The Hippocratic tradition held that aging was caused by a progressive loss of the body's store of heat, which resulted in a depletion of vitality and increased vulnerability (Thane, 1993). At birth it was assumed that we were granted a finite supply of energy. During childhood it was used for growth. At maturity we were to maintain a balance with our environment, but in old age we decayed as our remaining energy was spent. Benjamin Rush, a signer of the Declaration of Independence, stated that the loss of vitality led to a ''predisposing debility.'' The older individual became unable to remain in balance with the world (Haber, 1986).

In this short overview of frailty I'll deal first with select models and mechanisms for the development of frailty. I'll then present a working definition followed by an examination of the currently favored criteria for the identification of frail older persons.

Models and Mechanisms

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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