Special Article
Asian Working Group for Sarcopenia: 2019 Consensus Update on Sarcopenia Diagnosis and Treatment

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Abstract

Clinical and research interest in sarcopenia has burgeoned internationally, Asia included. The Asian Working Group for Sarcopenia (AWGS) 2014 consensus defined sarcopenia as “age-related loss of muscle mass, plus low muscle strength, and/or low physical performance” and specified cutoffs for each diagnostic component; research in Asia consequently flourished, prompting this update. AWGS 2019 retains the previous definition of sarcopenia but revises the diagnostic algorithm, protocols, and some criteria: low muscle strength is defined as handgrip strength <28 kg for men and <18 kg for women; criteria for low physical performance are 6-m walk <1.0 m/s, Short Physical Performance Battery score ≤9, or 5-time chair stand test ≥12 seconds. AWGS 2019 retains the original cutoffs for height-adjusted muscle mass: dual-energy X-ray absorptiometry, <7.0 kg/m2 in men and <5.4 kg/m2 in women; and bioimpedance, <7.0 kg/m2 in men and <5.7 kg/m2 in women. In addition, the AWGS 2019 update proposes separate algorithms for community vs hospital settings, which both begin by screening either calf circumference (<34 cm in men, <33 cm in women), SARC-F (≥4), or SARC-CalF (≥11), to facilitate earlier identification of people at risk for sarcopenia. Although skeletal muscle strength and mass are both still considered fundamental to a definitive clinical diagnosis, AWGS 2019 also introduces “possible sarcopenia,” defined by either low muscle strength or low physical performance only, specifically for use in primary health care or community-based health promotion, to enable earlier lifestyle interventions. Although defining sarcopenia by body mass index–adjusted muscle mass instead of height-adjusted muscle mass may predict adverse outcomes better, more evidence is needed before changing current recommendations. Lifestyle interventions, especially exercise and nutritional supplementation, prevail as mainstays of treatment. Further research is needed to investigate potential long-term benefits of lifestyle interventions, nutritional supplements, or pharmacotherapy for sarcopenia in Asians.

Section snippets

Consensus Process

AWGS founding members (L. K. Chen, H. Arai, J. Woo, C. W. Won, and P. Assantachai) used PubMed searches to identify other researchers with pertinent expertise from Asian countries or regions, whom they invited to lead special interest groups on the topics of epidemiology, case-finding, diagnosis, muscle mass, muscle strength, physical performance, and treatment. Group leaders were appointed at face-to-face meetings in Nagoya, Japan, and tasked to recruit members to help them source and appraise

Definition of Sarcopenia

The definition and diagnosis of sarcopenia are still evolving as new findings challenge current understanding. Nevertheless, given limited Asian data and controversy about using the term sarcopenia where muscle wasting may predominantly be due to coexisting conditions such as cachexia or paralysis, the AWGS decided against following a recent trend to consider all muscle wasting as sarcopenia and therefore retains its original definition of “age-related loss of skeletal muscle mass plus loss of

Epidemiology

The review of epidemiology studies from Asian countries that used AWGS 2014 criteria discovered that the prevalence of sarcopenia ranged from 5.5% to 25.7%, with male predominance (5.1%-21.0% in men vs 4.1%-16.3% in women) (Supplementary Table 1)12, 13, 14,S1, S2, S3, S4, S5, S6, S7, S8, S9, S10; the prevalence became more consistent—7.3% to 12.0%—if only studies with more than 1000 male and female participants were included.12, 13, 14,S9 Older age may be the most important among numerous

Diagnosis of Sarcopenia

Figure 1 shows the AWGS 2019 algorithm for identifying and diagnosing older adults with or at-risk for sarcopenia, including case-finding, assessment, and diagnostic protocols for use in either hospital and research settings, or in community-based health care and screening.

The special interest group review of sarcopenia diagnosis discovered that most studies done in Asian countries had used the AWGS 2014 criteria. Following extensive deliberations, AWGS 2019 contends that diagnosing sarcopenia

Case-finding

The case-finding special interest group reviewed studies from East and Southeast Asia that used screening or assessment instruments to identify early signs of sarcopenia. Based on related validation reports, AWGS 2019 recommends using either calf circumference (CC) or the SARC-F or SARC-CalF questionnaires for case-finding.

The recommended protocol for CC measures the maximum value of both calves using a nonelastic tape, which has moderate-to-high sensitivity and specificity in predicting

Skeletal Muscle Mass Measurement

The special interest group review on muscle mass measurement focused on techniques, body-size adjustment methods, and determining cutoff values. Although magnetic resonance imaging, computed tomography, dual-energy X-ray absorptiometry (DXA), and BIA have all been used to estimate skeletal muscle mass, DXA and BIA were the most commonly used modalities in Asia, and the AWGS 2014 cutoffs were widely adopted. BIA measurement with a multifrequency device correlated more closely with DXA-measured

Muscle Strength

Almost all studies in East and Southeast Asia that focused on muscle strength, function, and sarcopenia had used handgrip strength to indicate skeletal muscle strength; therefore, AWGS 2019 retains the recommendation to use handgrip strength. Although handgrip strength was widely used, measurement protocols varied between studies. The devices used most often in Asia are the spring-type dynamometer (Smedley), followed by hydraulic-type (Jamar);42 AWGS 2019 recommends using either device to

Physical Performance

Published research used a wide range of physical performance tests, including the Short Physical Performance Battery (SPPB), usual gait speed, 6-minute walk test, stair-climb power test, timed-up-and-go test, and 5-time chair stand test.4, 5, 6 Usual gait speed was the most frequently used test and was strongly associated with the onset of disability, severe mobility limitation, and mortality (Table 2).23, 24, 25,33,46, 47, 48,S3, S5, S13, S25, S26, S27, S28, S29,S35, S36, S37, S39, S40, S41,

Treatment and Intervention

A systematic review of randomized controlled trials (RCTs) through 2016 examined the effects of exercise, nutrition, combined exercise and nutrition, and pharmacologic agents on sarcopenia.9 For people with sarcopenia as defined by EWGSOP 2010, AWGS 2014, or combined muscle mass and function and/or strength, exercise alone effectively increased ASM and gait speed. Meta-analysis of 12 RCTs (not exclusively using AWGS 2014 or EWGSOP 2010 criteria) showed variable effects of nutrition alone on

Implications for Practice, Policy, and Research

AWGS 2019 highlights the impact of sarcopenia in all health care settings and recommends individualized lifestyle intervention that may be implemented across the health care spectrum. To promote healthy aging, AWGS 2019 has defined a new entity of “possible sarcopenia” to facilitate timely lifestyle intervention in community health care and prevention settings, which will contribute to higher awareness of sarcopenia prevention and interventions in diverse health care settings. However, more

Acknowledgments

Dr David Neil, of Full Universe Integrated Marketing, Taipei, Taiwan, provided editorial assistance and his colleague Pei Chi Kuo assisted with manuscript preparation and project management; Taipei Veterans General Hospital and Ministry of Science and Technology, Taiwan (MOST-107-2634-F-010-001) supported these contributions.

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  • This research was supported by funding from the National Center for Geriatrics and Gerontology (NCGG), Research Funding for Longevity Sciences (28-30) Japan, the Hong Kong Geriatrics Society (HKGS) and the Taiwan Association of Integrated Care (TAIC). The NCGG, HKGS, and TAIC were not involved in designing the study, nor subject recruitment, acquiring or analyzing data, or preparing the article.

    The authors declare no conflicts of interest.

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