Overview of Sarcopenia

Overview of SarcopeniaBackgroundSarcopenia is age related disease with symptoms of sacking of musculus pickle, loudness and function. Elderly over the age of 65 days argon vulnerable to sarcopenia 6. It is estimated that approximated 5-13% of honest-to-god people aged 6070 years are suffered from sarcopenia 8. The counterpoise is about twice higher among sr. at the age of 80 or above 8. Studies also plunge that sarcopenia is more likely seen in older men than older women 16,26. Sarcopenia gains intensive attention from public and increasing researches indicated that it is a major clinical b separatewise for older people.Risk factors of sarcopeniaCurrent research ensnare that lifestyle factors, including tangible inactivity, smoking and alcohol consuming 3 and biological factors, including older age, gender, decreased endocrine level, travel unit remodeling and reduced protein synthesis 3,25, contri excepte to development of sarcopenia. labor unit remodeling comes up of age and scarpers to replacement of fast twitch motor neuron22,25 which results in less precise control of movements, less force outturn and s pocket-sizeing of tendon mechanics22,23,25 as remodeled motor unit are bittie in size and slower to contract. Therefore, loss of fast twitch fibers increases chance of infection of having sarcopenia.In addition, protein synthesis, growth hormone (GH), studyosterone (T) and insulin-like growth factor (IGF-1) are considered to be associated with sarcopenia as well 25. It is well known that protein is important in muscle repairmen. And GH, T and IGF-1 are involved in protein metabolism and maintenance 23. distinguishable studies agreed that protein synthesis rate decreases throughout the natural aging handle 24 and leads to loss of muscle mint candy. Thus, low protein synthesis rate, along with decrease in these hormones level provide possible occurrence of sarcopenia 25.Consequences of sarcopeniaSarcopenia causes serious consequences not notwithstanding at individual level but also at societal level. On the one hand, loss of muscle heap, stance and function lead to adverse health outcome in terms of frailty, disability, morbidity and mortality rate 8. Essentially, sarcopenia is about twice as common as frailty 9. Also, sarcopenia occurs with other morbidity in some times. Some of the co-morbidity are obesity 4,13, hypertension, osteoporosis 12 and typecast II diabetes 5,14,15. Moreover, research suggests that loss of skeletal muscle strength whitethorn predict future mortality in middle-aged and elderly 2. On the other hand, sarcopenia is linked with increased healthcare outgo. In United States, the estimated organize healthcare attributable to sarcopenia fend fored about 1.5% of total healthcare expenditure in 2000 21.Diagnosis of sarcopenia according to different consensus panelsAlthough research working in the area of sarcopenia is expanding exponentially, a universal definition is still under develo pment. On average, current definitions are including muscle flowerpot, muscle strength or blush sensual function.In 2010, the European Working Group on Sarcopenia in Older People (EWGSOP) published guidelines to help identify sarcopenia 1,9. According to the EWGSOP, a person will be classified as having sarcopenia when two of third follow criteria were statisfied (A) low muscle mass and (B) low muscle strength and/or (C) low personal performance 1. Low muscle mass is define as muscle mass 2 standard deviations downstairs the mean of reference state 8, calculating by equipment such as DEXA-scanners. Low somatic performance is defined as gait revive 0.8 m/s in the 4 meters walk test for two males and females 8.International Working Group on Sarcopenia (IWGS) suggested diagnosing sarcopenia when the following criteria are fulfilled (a) gait speed was 1 m/s and (b) low muscle mass (cut take value is similar to EWGSOP) 8.The European Society of parenteral and Enteral Nutriti on Special Interest Groups carried out that the cut off values for low muscle mass is defined as dower of muscle mass 2 SDs below the mean of reference individuals for walk speed is 0.8 m/s in the 4 meters walk test 1.Measurement of muscle mass and muscle strengthMuscle strength is mainly pass judgmented by handgrip. While physical performance can be measured using simple tests such as the short physical performance battery test, usual gait speed or the clock get-up-and-go test it is difficult to assess muscle mass in practice. Dual-energy X-ray absorptiometry (DEXA) is recently proposed as the gold standard for muscle mass measurement. Other methods include bioelectrical impedance, computed tomography, magnetic resonance imaging, urinary excretion of creatinine, anthropometrical assessments, and neutron activation assessments can be used for measurement of muscle mass as well 8. The process is complicated and need participation of professionals. prevalence of sarcopenia varie s as use of cut-off points relies on different instruments used for assessing muscle mass and strength and function.SARC-F, a newly developed simple questionnaire, has been regarded as quick diagnosis test for sarcopenia. It contains five components strength, assistance in walking, elevator from a chair, climb stairs and falls. A question will be asked to assess each component variable. Scores range from 0-10, with 0-2 for each component 7. details of SARC-F are shown in table 1. Cut-off scoreA research conducted in Hong Kong tests the validation of SARC-F as a screening tool for sarcopenia in community. It found that SARC-F is able to predict future adverse outcomes with comparable power to other criteria. It also found that SARC-F has excellent specificity (94.4%) and negative predictive value but poor sensitivity. With high specificity, SARC-F is useful for screening out older adults with sarcopenia. hapless sensitivity may due to the number of participants classified as havi ng sarcopenia represent only a small proportion of the total population analyze 10.Another research applied SARC-F in mainland China to screen sarcopenia and physical disability. It published that poor physical performance and grip strength were associated with SARC-F defined sarcopenia. But there was a very weak correlation to muscle mass in physically active outpatients. It pointed out potential chronicle that the weak correlation may partly due to only small sample measured by DXA or BIA 11.Relevance to Public wellnessSarcopenia is coming of age. Elderly population is expected to remain on a rising trend in most of developed countries. In Hong Kong the proportion of the population aged 65 and over is projected to rise markedly from 13% in 2012 to 30% in 2041 . It means that increasing population will suffer from sarcopenia.It is not surprise that sarcopenia increase the risk of physical disability. The risk of disability is 1.5 to 4.6 times higher in older persons with sarcopenia than in older persons with normal muscle. Men are at greater risk of sarcopenia related disability than women 16. Recent estimates indicate that approximately 45% of the older U.S. population is sarcopenic and that approximately 20% of the older U.S. population is functionally change 21. It is important to note that physical disability is associated with an increased risk of nurse home placement, home healthcare and hospital use 21. And these healthcare operate need extra healthcare expenditure to support. To sum up with cultivation above, sarcopenia is becoming big challenge in public along with the rise of older population. It is cause serious health consequences in persons and make economic burden in countries.