Aging and Deficit Accumulation : Clinical Implications

Overview of Frailty

Geriatricians have an affinity for frail older people, or should. The complex care of older adults who are frail is the very stuff of geriatric medicine. This chapter argues that the formal assessment of complexity can be used to understand the scientific basis of the analyses of frailty, with insights for the practice of geriatric medicine. It takes the view that aging can be understood as the process of deficit accumulation, from subcellular to tissue to organ levels, becoming manifest clinically along the way. Although everyone, as they grow older, has a greater risk of death, not everyone of the same age has the same risk. People at an increased risk are frail for their age; those at lower risk are fit. Although related to age, there is some level of risk that conveniently defines everyone at that level as frail; a corollary is that there is likely some age at which everyone can be considered frail.

The basis for the variable risk of adverse outcomes of people of the same age lies in the variable rates at which people accumulate deficits. In essence, people with the greatest number of health deficits are at the greatest risk of death. The reason that the risk of death, on average, rises with age is because, on average, health deficits accumulate, and this occurs, in general because recovery times increase. In short, frail older adults are at an increased risk, compared with others of the same chronologic age, as a consequence of having multiple, interacting, age-related physiologic impairments, some of which cross clinical thresholds to be recognized as diseases and others as disabilities. These impairments, diseases, and disabilities typically interact with various social vulnerability factors, which commonly travel with the frail to increase the risk of adverse health outcomes further.

The view of frailty as a multiple-determined, at-risk state is reasonably noncontroversial. By contrast, how best to operationalize frailty consumes a lot of discussion. As outlined in Chapter 14 , the “phenotypic” definition of frailty used in the Cardiovascular Health Study is popular. So too is the view of frailty as deficit accumulation, the focus of this chapter.