- Sarcopenia describes the accelerated loss of skeletal muscle, manifesting as a combination of low strength and low muscle mass.
- Frailty can be described as a collective deterioration in multiple body systems, leading to a reduced ability to maintain homeostasis and respond to physiological stresses imposed on the body .
Sarcopenia and frailty are syndromes that become increasingly prevalent at older ages . Both conditions are important and are associated with adverse health care outcomes, including disability and mortality. Its evaluation in clinical practice is increasingly widespread and provides the opportunity to identify people at risk of poor health and begin relevant treatments.
| Diagnosis |
Several diagnostic criteria have been proposed for sarcopenia, based on the combination of low muscle strength and low muscle mass. A recent example is the revised consensus definition of the European Working Group on Sarcopenia in Older People (EWGSOP).
The first step is to identify possible cases of sarcopenia using the short SARC-F questionnaire, which asks about about 5 items, including climbing a flight of stairs. Any difficulty with these actions suggests the need for further evaluation, as do a range of clinical risk factors, including multimorbidity (the presence of ≥2 long-term conditions) and cognitive impairment.
The next step in defining EWGSOP is to assess muscle strength , with 2 methods recommended for clinical practice.
1. The first is grip strength , measured with a manual dynamometer, with 3 trials for each hand, at the maximum value being used. Grip strength correlates with strength in other areas of the body. There is low strength when the maximum grip strength is <16 kg in women and <27 kg in men.
2. The second method is to get up 5 times from the sitting position, as quickly as possible, without using your arms. A time of ≥15 seconds indicates poor muscle strength.
3. The next step to confirm sarcopenia in people with low strength is to assess muscle mass , specifically in the arms and legs (called appendicular lean mass). The most widely used available techniques are, in clinical practice, dual-energy
Frailty can be diagnosed using 3 main approaches :
- The phenotypic model
- The cumulative deficit model
- The clinical model, using the Frailty Scale (EF).
Fired et al. described a phenotypic model of 5 frailty criteria consisting of weight loss, weakness, little physical activity, slow gait and exhaustion . If a patient has ≥3 of these criteria, they are considered to have frailty; Compliance with 1 or 2 criteria corresponds to prefragility.
Rockwood described the cumulative deficit model , based on the proportion of a number of possible deficits and symptoms present, including physical, sensory and cognitive impairments, and medical and psychiatric conditions. He also created the Frailty Scale , a pictorial representation of levels of functional impairment corresponding to a frailty severity from 1 (very fit) to 8 (very severe frailty).
All 3 approaches to diagnosing frailty contain aspects of muscle strength or physical function, so there is a substantial degree of overlap between the definitions of sarcopenia and frailty.
| Epidemiology |
> Prevalence
Due to the overlapping characteristics of sarcopenia and frailty, it follows that the prevalence of these syndromes follows similar patterns.
Prevalence estimates vary with the exact definition used, as the prevalence of sarcopenia in a cohort with a mean age of 67 years was found to be 6.5%, increasing to 21% in another cohort aged 85 years. It was also found that the phenotypic model showed that the prevalence was 6.5% at the age of 60-69 years, rising to 31% in those aged 80-89 years.
The presence of ≥2 long-term conditions (multimorbidity) is a risk factor for sarcopenia and frailty syndromes, and may lead to them being observed at younger ages. One study found a similar prevalence of sarcopenia in individuals aged 40 to 49 years with ≥3 categories of long-term conditions. In people aged 60 to 70 years with only 1.
People with frailty are very likely to have multimorbidity : a previous meta-analysis found that 72% of people with frailty as defined by Fried had ≥2 long-term conditions. However, the opposite was not seen: only 16% of people with multimorbidity in the same study showed frailty.
| Associations with health outcomes |
Sarcopenia and frailty are associated with a range of negative health effects, including the development or progression of disability, admission to long-term care, increased risk of falls and decreased quality of life.
The most striking result associated with sarcopenia and frailty increases the risk of death .
Estimates based on the strength of these associations vary depending on the definition used and the population studied. Sarcopenia appears to lead to a nearly doubling of overall mortality risk. Frailty, based on Fried’s definition, has been linked to at least this level of increased risk, often the highest.
Insert Lower grip strength is associated with poor health outcomes: a poorly considered prognostic marker Grip strength is likely a marker of many factors that may predispose patients to illness, disability, and death. The primary role of skeletal muscle is to control body movements through force generation. Skeletal muscle is also the main protein store within the body and in chronic conditions, such as cancer, and can provide gluconeogenic precursors that are crucial for survival as such conditions progress. In addition to this, skeletal muscle is the main outlet for glucose in the body and is therefore important in metabolic conditions such as diabetes. Muscle mass is also decreased (cachexia) in many conditions, such as cancer, respiratory diseases, chronic kidney disease, and chronic infection and sepsis. With these physiological characteristics and functional roles, skeletal muscle plays a critical, but often underappreciated, role in health. Many studies have shown that lower muscle function is associated with higher mortality and morbidity. For example, in male adolescents (16-19 years of age) followed for 24 years, low muscle strength was associated with increased all-cause mortality and mortality from cardiovascular disease, but not cancer. Grip strength was inversely associated with all-cause mortality. Recent data from the Prospective Urban Rural Epidemiology (PURE) study (n = 139,691 adults aged 35-70 years followed for four years) showed that grip strength was inversely associated with all-cause mortality and with cardiovascular and mortality. non-cardiovascular, but no significant association was found with respiratory disease and chronic obstructive pulmonary disease. Furthermore, lower grip strength was found to be positively associated with incident cancer in high-income countries but not in middle- or low-income countries. The authors of this study concluded that although some data support an association between grip strength and mortality, more research is needed to confirm this association with other health outcomes. |
| Driving |
Patients with sarcopenia and frailty will benefit from treatments to improve strength and muscle mass. However, the strongest evidence is for the use of progressive resistance training.
In people with less mobility, the ability to participate in such exercise regimens may be limited. There is less evidence for the benefit of dietary interventions, but an increase in protein intake of 1.0 to 1.2 g/kg body weight/day is recommended in older adults.
There is also evidence that vitamin D replacement in women with low serum concentrations improves strength and physical functioning. There are currently no medications approved to treat sarcopenia and frailty.
The primary approach to managing a frail older person is an individualized and holistic process known as Comprehensive Geriatric Assessment (CGE). It is a multidisciplinary process that covers medical, functional, social and psychological aspects, to provide extensive and personalized care, with a care plan aimed at promoting health and independence. The application of EGI in people with frailty during acute hospitalization has been associated with lower risks of both death and institutionalization.
| Importance during acute hospital admission |
Sarcopenia is not usually evaluated during hospitalization, although there is increasing awareness of the risks of deconditioning (including muscle loss) during acute illness .
In comparison, assessment of frailty in older people, for example using the EGI, has become widespread at hospital admission. The Acute Frailty Network is a support network that has helped hospitals implement such tools. It is important to highlight that the identification of frailty should lead to a prompt Comprehensive Geriatric Evaluation (CGE); As described above, this has been shown to improve outcomes in hospitalized frail elderly.
| Prevention |
There is interest in whether sarcopenia and frailty could be prevented, or delayed, by interventions earlier in life. Regarding muscle strength , there is an increase in childhood and early adulthood, followed by extensive maintenance in middle age before loss in old age.
It follows that factors that influence muscle strength in old age include those that affect the maximum level achieved in the first years of life and the rate of loss in old age. For example, evidence from a British birth cohort study suggests that increased leisure-time physical activity throughout adulthood is associated with a stronger grip in old age and therefore lower odds of of sarcopenia and frailty.
