Frailty in Pulmonary and Critical Care Medicine

Abstract

Conceptualized first in the field of geriatrics, frailty is a syndrome characterized by a generalized vulnerability to stressors resulting from an accumulation of physiologic deficits across multiple interrelated systems. This accumulation of deficits results in poorer functional status and disability. Frailty is a "state of risk" for subsequent disproportionate declines in health status following new exposure to a physiologic stressor. Two predominant models have emerged to operationalize the measurement of frailty. The phenotype model defines frailty as a distinct clinical syndrome that includes conceptual domains such as strength, activity, wasting, and mobility. The cumulative deficit model defines frailty by enumerating the number of age-related things wrong with a person. The biological pathways driving frailty include chronic systemic inflammation, sarcopenia, and neuroendocrine dysregulation, among others. In adults with chronic lung disease, frailty is independently associated with more frequent exacerbations of lung disease, all-cause hospitalization, declines in functional status, and all-cause mortality. In addition, frail adults who become critically ill are more likely develop chronic critical illness or severe disability and have higher in-hospital and long-term mortality rates. The evaluation of frailty appears to provide important prognostic information above and beyond routinely collected measures in adults with chronic lung disease and the critically ill. The study of frailty in these populations, however, requires multipronged efforts aimed at refining clinical assessments, understanding the mechanisms, and developing therapeutic interventions.

Keywords: body composition; disability; frailty; health-related quality of life; mortality.

Figure 1.

(A) Hypothetical trajectories of functional status for patients experiencing recurrent acute exacerbations of chronic lung disease who are frail (red line) and not frail (blue line). Frail patients are susceptible to more frequent exacerbations with less recovery in between, resulting in faster loss of functional status, earlier onset of disability, and a shorter lifespan. (B) Hypothetical trajectories for patients who are frail (red line) or not frail (blue line) prior to becoming critically ill. The thickness of the trajectory lines represents the proportion of patients in each trajectory. For a given insult, frail patients are susceptible to becoming critically ill sooner. Patients who are frail prior to critical illness are more likely to die in the hospital and more likely to develop chronic critical illness or severe disability leading to an early death. If they survive their critical illness, they are prone to recover functional status more slowly or develop permanent disability and a shorter lifespan than those who are not frail.

Figure 2.

Hypothesized genetic, molecular, and functional changes underlying the frailty phenotype. Adapted by permission from References , , and .