Special ArticleSarcopenia: An Undiagnosed Condition in Older Adults. Current Consensus Definition: Prevalence, Etiology, and Consequences. International Working Group on Sarcopenia
Section snippets
Current Consensus Definition
A meeting was convened on November 18, 2009, in Rome, Italy, with the express purpose of arriving at a consensus definition of sarcopenia. Because there has been no true consensus of the appropriate criteria for when an individual may be said to be sarcopenic, recognition of this treatable condition has been lacking. The following definition was the current consensus of the group of scientists and geriatricians who were present at the meeting. In addition, this definition was reviewed by a
Muscle Aging
Over the age span from 20 to 80 years of age, there is approximately a 30% reduction in muscle mass and a decline in cross-sectional area of about 20%.14 This is because of a decline in both muscle fiber size and number.10 There is no consensus on whether there is a selective loss of specific muscle fiber types. Early cross-sectional studies demonstrated a shift in muscle fiber composition with a higher type I/type II fiber ratio with advancing age.11 Larsson12 suggested a preferential loss of
Etiology and Biochemical Basis for Sarcopenia
Sarcopenia is a universal phenomenon with a complex, multifactorial etiology. Many of the potential causes vary by the age of the individual and are summarized in Table 3. The major factors considered to be involved include genetic heritability,41, 42, 43 nutritional status (protein intake, energy intake, and vitamin D status),30, 44, 45, 46, 47, 48 physical activity,49, 50, 51, 52 hormonal changes (declines in serum testosterone and growth hormone),31, 53 insulin resistance,54, 55, 56
Epidemiology
The measurement of muscle mass in humans is difficult, with most of the available methods requiring assumptions that may not always be valid and with variable degrees of accuracy and difficulty. The most direct measurement currently available is urinary creatinine measured over 24-hour periods.67 Other, more indirect, measures include anthropometry,68 bioelectrical impedance, DXA,69 imaging techniques (eg, computed tomography and magnetic resonance imaging), ultrasound, total body potassium,
Sarcopenia and Disability
Sarcopenia is correlated with functional decline and disability.5, 16, 80, 85, 90 Findings are often stronger in men than in women, depending on the indexing method used. Sarcopenia has also been associated with increased mortality,91 although92 weakness has been demonstrated to be a more powerful predictor of mortality in elderly people than muscle mass. In the longitudinal Rancho Bernardo study, sarcopenia was shown to be predictive of falls.81 Janssen93 examined 5036 men and women older than
Conclusion
Sarcopenia represents a major cause of disability and increased health costs in older persons. It is very common, but like most geriatric syndromes, seldom recognized by physicians. Identification of sarcopenic patients at greatest risk can be performed using an easy-to-perform assessment of mobility, such as gait speed and commonly obtained measures of body composition.101 DXA instruments are used to assess bone density for the identification of those at greatest risk for the development of
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Partial support for this meeting, in the form of travel costs, was provided by GlaxoSmithKline and Abbott, Chiesi, Danone, Merck, Nestlé, Novartis, and Sanofi Aventis.
From the International Sarcopenia Consensus Conference Working Group Meeting, Rome, Italy, November 18, 2009.