Frailty for Perioperative Clinicians: A Narrative Review

Daniel I. McIsaac, MD, MPH, FRCPC; David B. MacDonald, MD, FRCPC; Sylvie D. Aucoin, MD, MSc, FRCPC


Anesth Analg. 2020;130(6):1450-1460. 

In This Article

What Is (or Isn't) Frailty?

Frailty is a multidimensional syndrome characterized by decreased reserves that leaves an individual vulnerable to adverse outcomes due to decreased tolerance of stressors (physical, physiologic, or psychosocial).[11–14] However, conceptualizing the specific features that underly frailty has eluded consensus. In general, experts agree that frailty is a multidimensional construct that includes deficits related to physical performance, nutritional status, mental health, and cognition.[14] Consensus has not been reached, however, on how to operationalize measurement of physical performance, nutrition, mental health, or cognition in clinical frailty assessments.

There is consensus, however, regarding what frailty isn't. First, although related, frailty is distinct from concepts such as disability and comorbidity.[11] Next, although investigators have occasionally defined frailty in research settings using single laboratory or diagnostic imaging values (eg, hypoalbuminemia, muscle cross-sectional area [a measure of sarcopenia]), these values on their own cannot allow direct measurement of an individual's frailty status.[14] Furthermore, although deficits will accumulate during the normal aging process, frailty is not directly synonymous with aging, but can instead be used to better identify individuals who are substantially more vulnerable relative to others of the same age.[13] Finally, the prevalence of frailty increases exponentially with increased age; however, frailty is not solely a geriatric syndrome. In fact, several studies in perioperative and critical care medicine have found that the presence of frailty at younger ages is associated with a greater relative risk of adverse outcome than frailty present in older individuals.[15,16]

In the perioperative setting, a useful definition is that frailty is an aggregate expression of risk that results from accumulation of age- and disease-related deficits across multiple domains.[17,18] This definition reflects the fact that frailty represents a global risk state (eg, it is not solely a risk factor for single organ complications), that frailty status can be impacted both by processes of aging (such as cellular and tissue breakdown) and disease-specific processes (eg, proinflammatory features of diabetes, or decreased cardiac function in coronary artery disease) and that frailty is a multidimensional entity that cannot be quantified by a single measurement.

Two leading frameworks are currently used to conceptualize frailty (Figure 1).[12] The first is the phenotype model,[17] where the presence of frailty is thought to be a primarily internal phenomenon occurring at the cellular level, caused by breakdown and dysregulation of energetics that are expressed phenotypically. This phenotype can then be identified through the measurement of gait speed, grip strength, energy levels, weight loss, and falls. The second conceptual framework is the accumulating deficits model.[13,19] In this approach, frailty is thought of as a measurement of the biologic (as opposed to chronologic) aging process; instead of counting calendar years, one counts the number of deficits present across multiple domains (≥30 deficits must be assessed).[20] The degree of frailty present can then be quantified by dividing the number of deficits present by the number of deficits assessed, which generates a score between 0 (no frailty) and 1 (completely frail). Regardless of the conceptual framework, however, it is crucial to recognize that frailty, although often described as being present or absent, is best used as a graded condition where higher levels of frailty equate to greater vulnerability and risk of adverse outcomes.

Figure 1.

The relationship between domains contributing to frailty, conceptual frameworks, and commonly used frailty instruments (CSHA, FRAIL, RAI). (Terms of Use: This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License. It is attributed to Daniel McIsaac.) CSHA indicates Canadian Study of Health and Ageing; FRAIL, Fatigue, Resistance, Ambulation, Illnesses, & Loss of weight; RAI, Risk Analysis Index.