| Frailty syndrome | |
|---|---|
| Specialty | Geriatrics |
A walker in the apartment of a senior woman
Frailty is a common geriatric syndrome that embodies an elevated risk of catastrophic declines in health and function among older adults. Frailty is a condition associated with ageing, and it has been recognized for centuries. As described by Shakespeare in As You Like It,
"the sixth age shifts into the lean and slipper’d pantaloon, with
spectacles on nose and pouch on side, his youthful hose well sav’d, a
world too wide, for his shrunk shank…". The shrunk shank is a result of
loss of muscle with aging. It is also a marker of a more widespread
syndrome of frailty, with associated weakness, slowing, decreased
energy, lower activity, and, when severe, unintended weight loss.
As a population ages, a central focus of geriatricians and public
health practitioners is to understand, and then beneficially intervene
on, the factors and processes that put elders at such risk, especially
the increased vulnerability to stressors (e.g. extremes of heat and
cold, infection, injury, or even changes in medication) that
characterizes many older adults.
Epidemiology
Frailty
is a common geriatric syndrome. Estimates of frailty's prevalence in
older populations may vary according to a number of factors, including
the setting in which the prevalence is being estimated – e.g., nursing
home (higher prevalence) vs. community (lower prevalence), and the
operational definition used for defining frailty. Using the widely used
frailty phenotype framework proposed by Fried et al. (2001), prevalence estimates of 7–16% have been reported in non-institutionalized, community-dwelling older adults.
The occurrence of frailty increases incrementally with advancing
age, and is more common in older women than men, and among those of
lower socio-economic status. Frail older adults are at high risk for
major adverse health outcomes, including disability, falls,
institutionalization, hospitalization, and mortality.
Epidemiologic research to date has led to the identification of a
number of risk factors for frailty, including: (a) chronic diseases,
such as cardiovascular disease, diabetes, chronic kidney disease,
depression, and cognitive impairment; (b) physiologic impairments, such as activation of inflammation and coagulation systems, anemia, atherosclerosis, autonomic dysfunction, hormonal abnormalities, obesity, hypovitaminosis D in men, and environment-related factors such as life space and neighborhood characteristics.
Advances about potentially modifiable risk factors for frailty now
offer the basis for translational research effort aimed at prevention
and treatment of frailty in older adults. A recent systematic review
found that exercise interventions can increase muscle strength and
improve physical function; however, results are inconsistent in frail
older adults living in the community.
Theoretical understanding
Recent
work on frailty has sought to characterize both the underlying changes
in the body and the manifestations that make frailty recognizable. It
is well-agreed upon that declines in physiologic reserves and resilience
is the essence of being frail.
Similarly, scientists agree that the risk of frailty increases with
age and with the incidence of diseases. Beyond that, there is now strong
evidence to support the theory that the development of frailty involves
declines in energy production, energy utilization and repair systems in
the body, resulting in declines in the function of many different
physiological systems. This decline in multiple systems affects the
normal complex adaptive behavior that is essential to health
and eventually results in frailty typically manifesting as a syndrome
of a constellation of weakness, slowness, reduced activity, low energy
and unintended weight loss. When most severe, i.e. when 3 or more of these manifestations are present, the individual is at a high risk of death.
Assessment of geriatric frailty
The
syndrome of geriatric frailty is hypothesized to reflect impairments in
the regulation of multiple physiologic systems, embodying a lack of
resilience to physiologic challenges and thus elevated risk for a range
of deleterious endpoints. Generally speaking, the empirical assessment
of geriatric frailty in individuals seeks ultimately to capture this or
related features, though distinct approaches to such assessment have
been developed in the literature (see de Vries et al., 2011 for a
comprehensive review).
Two key approaches are discussed below:
Linda Fried / Johns Hopkins Frailty Criteria
A
popular approach to the assessment of geriatric frailty encompasses the
assessment of five dimensions that are hypothesized to reflect systems
whose impaired regulation underlies the syndrome. These five dimensions
are:
- unintentional weight loss,
- exhaustion,
- muscle weakness,
- slowness while walking, and
- low levels of activity.
Corresponding to these dimensions are five specific criteria
indicating adverse functioning, which are implemented using a
combination of self-reported and performance-based measures. Those who
meet at least three of the criteria are defined as “frail”, while those
not matching any of the five criteria are defined as “robust”.
Additional work on the construct is done by Bandeen-Roche et al. (2006),
though some of the exact criteria and measures differ (see Table 1 in
the paper for this contrast). Other studies in the literature have also
adopted the general approach of Linda P. Fried et al. (2001)
though, again, the exact criteria and their particular measures may
vary. This assessment approach was developed and refined by Fried and
colleagues at the Johns Hopkins University’s Center on Aging and Health. This Center is home to Johns Hopkins Claude D. Pepper Older Americans Independence Center, which focuses on frailty research.
Rockwood Frailty Index
Another
notable approach to the assessment of geriatric frailty (if not also to
some degree its conceptualization) is that of Rockwood and Mitnitski
(2007)
in which frailty is viewed in terms of the number of health "deficits"
that are manifest in the individual, leading to a continuous measure of
frailty (see Rockwood, Andrew, and Mitnitski (2007) for a contrast of the two approaches). This approach was developed by Dr. Rockwood and colleagues at Dalhousie University.
Four domains of frailty
A four domains of frailty model was proposed in response to an article in the BMJ.
This conceptualisation could be viewed as blending the phenotypic and
index models. Researchers tested this model for signal in routinely
collected hospital data, and then used this signal in the development of a frailty model, finding even predictive capability across 3 outcomes of care.
In the care home setting, one study indicated that not all four domains
of frailty were routinely assessed in residents, giving evidence to
suggest that frailty may still primarily be viewed only in terms of
physical health.
SHARE Frailty Index
The SHARE-Frailty Index (SHARE-FI) was originally developed by Romero-Ortuno (2010) (https://bmcgeriatr.biomedcentral.com/articles/10.1186/1471-2318-10-57)
and researchers as part of the Survey of Healthy Ageing and Retirement
in Europe. It consists of five domains of the frailty phenotype:
•Fatigue
•Loss of appetite
•Grip strength
•Functional difficulties
•Physical activity.
The SHARE-FI calculator is freely available to use online.
The calculator classifies individuals as 1) frail; 2) pre-frail; and 3)
non-frail / robust.
The SHARE-FI has good clinical utility as it provides relatively quick
assessment of frailty in often time-poor healthcare settings.
Biological underpinnings
It
has been suggested that the biological underpinnings of frailty are
multifactorial, involving dysregulation across many physiological
systems. A proinflammatory state, sarcopenia, anemia, relative deficiencies in anabolic hormones (androgens and growth hormone) and excess exposure to catabolic hormones (cortisol), insulin resistance, glucose levels, compromised altered immune function, micronutrient deficiencies and oxidative stress
are each individually associated with a higher likelihood of frailty.
Additional findings show that the risk of frailty increases with the
number of dysregulated physiological systems in a nonlinear pattern,
independent of chronic diseases and chronologic age, suggesting
synergistic effects of individual abnormalities that on their own may be
relatively mild.
The clinical implication of this finding is that interventions that
affect multiple systems may yield greater, synergistic benefits in
prevention and treatment of frailty than interventions that affect only
one system.
Associations between specific disease states are also associated
with and frailty have also been observed, including cardiovascular
disease, diabetes mellitus, chronic kidney disease
and other diseases in which inflammation is prominent. To the extent
that dysregulation across several physiologic systems underlie the
pathogenesis of the frailty, specific disease states are likely
concurrent manifestations of the underlying impaired physiologic
function and regulation. It is possible that clinically measurable
disease states can manifest themselves or be captured prior to the onset
of frailty. No single disease state is necessary and sufficient for the
pathogenesis of frailty, since many individuals with chronic diseases
are not frail. Therefore, rather than being dependent on the presence of
measurable diseases, frailty is an expression of a critical mass of
physiologic impairments.
Components
Sarcopenia
Sarcopenia (from the Greek meaning "poverty of flesh") is the degenerative loss of skeletal muscle mass, quality, and strength associated with aging. The rate of muscle loss is dependent on exercise level, co-morbidities, nutrition and other factors. Sarcopenia
can lead to reduction in functional status and cause significant
disability from increased weakness. The muscle loss is related to
changes in muscle synthesis signalling pathways although is incompletely
understood. The cellular mechanisms are distinct from other types of
muscle atrophy such as cachexia, in which muscle is degraded through cytokine-mediated degradation although both conditions may co-exist.
Osteoporosis
Osteoporosis causes a hunched-over appearance in some people.
Osteoporosis is an age-related disease of bone that leads to an increased risk of fracture. In osteoporosis the bone mineral density
(BMD) is reduced, bone microarchitecture is disrupted, and the amount
and variety of proteins in bone is altered. Osteoporosis is defined by
the World Health Organization (WHO) in women as a bone mineral density 2.5 standard deviations below peak bone mass (20-year-old healthy female average) as measured by DXA; the term "established osteoporosis" includes the presence of a fragility fracture.
Osteoporosis is most common in women after menopause, when it is called postmenopausal osteoporosis, but may also develop in men, and may occur in anyone in the presence of particular hormonal disorders and other chronic diseases or as a result of medications, specifically glucocorticoids, when the disease is called steroid- or glucocorticoid-induced osteoporosis (SIOP or GIOP). Given its influence in the risk of fragility fracture, osteoporosis may significantly affect life expectancy and quality of life.
Muscle weakness
Muscle weakness, also known as muscle fatigue, (or "lack of strength") refers to the inability to exert force with one's skeletal muscles. Weakness often follows muscle atrophy
and a decrease in activity, such as after a long bout of bedrest as a
result of an illness. There is also a gradual onset of muscle weakness
as a result of sarcopenia - the age-related loss of skeletal muscle.
Muscle weakness makes it difficult to perform everyday activities, like getting into a bathtub.
A test of strength is often used during a diagnosis of a muscular disorder before the etiology
can be identified. Such etiology depends on the type of muscle
weakness, which can be true or perceived as well as variable topically.
True weakness is substantial, while perceived rather is a sensation of
having to put more effort to do the same task.
On the other hand, various topic locations for muscle weakness are
central, neural and peripheral. Central muscle weakness is an overall
exhaustion of the whole body, while peripheral weakness is an exhaustion
of individual muscles. Neural weakness is somewhere between.
Healing power
Physical injuries heal slower and are more likely to leave permanent scars in older people.
Aged people recover slower and are lesser likely to completely recover from physical injuries and accidents.
Surgical outcomes
Frail
elderly people are at significant risk of post-surgical complications
and the need for extended care. Frailty more than doubles the risk of
morbidity and mortality from surgery and cardiovascular conditions. Assessment of older patients before elective surgeries can accurately predict the patients' recovery trajectories.
The most widely used frailty scale consists of five items:
- unintentional weight loss >4.5 kg in the past year
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- self-reported exhaustion
- low physical activity such that persons would only rarely undertake a short walk
- slowed walking speed, defined as lowest population quartile on 4 minute walking test.
A healthy person scores 0; a very frail person scores 5. Compared to
non-frail elderly people, people with intermediate frailty scores (2 or
3) are twice as likely to have post-surgical complications, spend 50%
more time in the hospital, and are three times as likely to be
discharged to a skilled nursing facility instead of to their own homes.
Frail elderly patients (score of 4 or 5) have even worse outcomes,
with the risk of being discharged to a nursing home rising to twenty
times the rate for non-frail elderly people.
