Frailty in elderly people

Abstract

Frailty is the most problematic expression of population ageing. It is a state of vulnerability to poor resolution of homoeostasis after a stressor event and is a consequence of cumulative decline in many physiological systems during a lifetime. This cumulative decline depletes homoeostatic reserves until minor stressor events trigger disproportionate changes in health status. In landmark studies, investigators have developed valid models of frailty and these models have allowed epidemiological investigations that show the association between frailty and adverse health outcomes. We need to develop more efficient methods to detect frailty and measure its severity in routine clinical practice, especially methods that are useful for primary care. Such progress would greatly inform the appropriate selection of elderly people for invasive procedures or drug treatments and would be the basis for a shift in the care of frail elderly people towards more appropriate goal-directed care.

Figure 1

Vulnerability of frail older people to a sudden change in health status following a minor illness. The green line represents a fit older person who, following a minor stress such as an infection, experiences a relatively small deterioration in function and then returns to homeostasis. The red line represents a frail older person who, following a similar stress, experiences a larger deterioration which may manifest as functional dependency and who does not return to baseline homeostasis. Key: UTI: Urinary tract infection

Figure 2

A schematic representation of the pathophysiology of frailty. Ageing is considered to result from the lifelong accumulation of molecular and cellular damage caused by multiple mechanisms regulated by a complex maintenance and repair network under the influence of genetic, environmental and epigenetic mechanisms. There is uncertainty regarding the precise level of cellular damage required to cause impaired organ physiology but, importantly, many organ systems exhibit considerable redundancy, which provides the physiological reserve required to compensate for age and disease-related changes. The brain, endocrine system, immune system and skeletal muscle are intrinsically inter-related and are currently the organ systems best studied in the development of frailty. Loss of physiological reserve in other systems including the cardiovascular, respiratory and renal systems also contributes. Influenced by level of physical activity and nutritional factors, cumulative loss of physiological reserve in these organ systems can lead to frailty, which is characterised by increased vulnerability to poor resolution of homeostasis following a stress, increasing the risk of adverse outcomes including falls, delirium and disability. These are common clinical presentations of frailty, are common reasons for admission to hospital and can accelerate further decline. Both frailty itself and these common clinical presentations identify those at increased risk of requiring care at home and long-term care admission.