肌少症患者肌肉质量测评工具的研究进展

肌少症是肌肉质量和肌肉强度呈渐进性减少和下降的衰老综合征,可导致跌倒、骨折和失能等风险增高,对患者机体功能造成严重影响,极大降低了患者的生活质量,甚至导致死亡。为提高肌少症诊断和治疗效果,选择科学有效的测评工具十分重要。目前,各国际组织对肌少症的诊断标准仍未达成统一共识,尤其在肌肉质量测定部分存在较多争议。本文旨在通过复习总结相关国内外文献,阐述肌少症的筛查流程、诊断标准,重点探讨肌肉质量的测评工具及其优势与不足,以期为肌肉质量测评工具的选择及准确评估提供借鉴。     

肌肉减少症病因学研究现状与展望

肌肉减少症是一种与年龄有关的肌肉力量下降和躯体功能受限的老年综合征,老年人出现跌倒、身体残疾、住院和早逝等不良后果风险增加。人均寿命延长导致老龄化,肌肉减少症的发病率和患病率明显升高。2016年国际卫生组织将其纳入《国际疾病分类第十次修订版:临床修改》(ICD-10-CM),疾病编码为M62.84。目前肌肉减少症最常用的定义是欧洲老年人肌肉减少症工作组(EWGSOP)提出的,表示与增龄相关的进行性的全身肌肉量减少、肌肉强度下降或肌肉生理功能减退,2019年EWGSOP更新肌肉减少症定义。肌肉减少症被认为是晚年负面健康结果的相关决定因素,肌肉力量和活动能力的丧失导致躯体平衡障碍,老年人发生跌倒和骨折的比率升高,增加社会残疾率及医疗负担,明确病因十分重要。近年来国内外学者研究发现肌肉减少症与运动因素、内分泌因素、慢性炎症、营养状况、肠道菌群、遗传因素及社会心理素等相关,但具体病因尚不明确。本文通过查阅大量有关文献,对肌肉减少症病因学研究现状与进展作一综述。     

Sarcopenia

Sarcopenia is defined as a combination of low muscle mass with low muscle function. The term was first used to designate the loss of muscle mass and performance associated with aging. Now, recognized causes of sarcopenia also include chronic disease, a physically inactive lifestyle, loss of mobility, and malnutrition. Sarcopenia should be differentiated from cachexia, which is characterized not only by low muscle mass but also by weight loss and anorexia. Sarcopenia results from complex and interdependent pathophysiological mechanisms that include aging, physical inactivity, neuromuscular compromise, resistance to postprandial anabolism, insulin resistance, lipotoxicity, endocrine factors, oxidative stress, mitochondrial dysfunction, and inflammation. The prevalence of sarcopenia ranges from 3% to 24% depending on the diagnostic criteria used and increases with age. Among patients with rheumatoid arthritis 20% to 30% have sarcopenia, which correlates with disease severity. Sarcopenia exacts a heavy toll of functional impairment, metabolic disorders, morbidity, mortality, and healthcare costs. Thus, the consequences of sarcopenia include disability, quality of life impairments, falls, osteoporosis, dyslipidemia, an increased cardiovascular risk, metabolic syndrome, and immunosuppression. The adverse effects of sarcopenia are particularly great in patients with a high fat mass, a condition known as sarcopenic obesity. The diagnosis of sarcopenia rests on muscle mass measurements and on functional tests that evaluate either muscle strength or physical performance (walking, balance). No specific biomarkers have been identified to date. The management of sarcopenia requires a multimodal approach combining a sufficient intake of high-quality protein and fatty acids, physical exercise, and antiinflammatory medications. Selective androgen receptor modulators and anti-myostatin antibodies are being evaluated as potential stimulators of muscle anabolism.     

What’s in a name revisited: should osteoporosis and sarcopenia be considered components of “dysmobility syndrome?”

Sarcopenia and osteoporosis are age-related declines in the quantity and quality of muscle and bone respectively, with shared pathogeneses and adverse health consequences. Both absolute and relative fat excess, i.e., obesity and sarcopenic obesity, contribute to disability, falls, and fractures. Rather than focusing on a single component, i.e., osteoporosis, sarcopenia, or obesity, we realized that an opportunity exists to combine clinical factors, thereby potentially allowing improved identification of older adults at risk for disability, falls, and fractures. Such a combination could be termed dysmobility syndrome, analogous to the approach taken with metabolic syndrome. An arbitrary score-based approach to dysmobility syndrome diagnosis is proposed and explored in a small cohort of older adults. Further evaluation of such an approach in large population-based and prospective studies seems warranted.     

Operational definitions of sarcopenia and their associations with 5-year changes in falls risk in community-dwelling middle-aged and older adults

Summary

Sarcopenia may be diagnosed in the clinic using operational definitions based on low muscle mass or function. This prospective, population-based study revealed that sex-specific associations may exist between operational definitions of sarcopenia and falls in community-dwelling middle-aged and older adults.

Introduction

The objective of this study is to verify associations between sarcopenia and falls risk and to determine changes in sarcopenia prevalence over 5 years in middle-aged and older men and women according to different anthropometric and performance-based operational definitions.

Methods

N?=?681 volunteers (48 % female; mean?±?SD age 61.4?±?7.0 years) participated in baseline and follow-up assessments (mean 5.1?±?0.5 years later). Appendicular lean mass (ALM) was assessed by dual-energy X-ray absorptiometry, hand grip (HGS) and lower-limb (LLS) strength were assessed by dynamometry, and falls risk was determined using the physiological profile assessment. Anthropometric definitions (ALM/height squared [ALM–H], ALM/weight × 100 and a residuals method [ALM–R]) and performance-based definitions (HGS, LLS and upper- and lower-limb muscle quality [LMQ]) of sarcopenia were examined. The lowest 20 % of the sex-specific distribution for each definition at baseline was classified as sarcopenia.

Results

Sarcopenia prevalence increased after 5 years for all operational definitions except ALM–H (men: ?4.0 %; women: ?5.5 %). Men classified with sarcopenia according to anthropometric definitions, and women classified with sarcopenia according to performance-based definitions, had significant increases in falls risk over 5 years (all P?<?0.05) compared to individuals without sarcopenia. Significant sex interactions were observed for ALM-R, LLS and LMQ (all P?<?0.05) definitions.

Conclusions

Sarcopenia prevalence generally increases at a higher rate when assessed using performance-based definitions. Sarcopenia is associated with increases in falls risk over 5 years in community-dwelling middle-aged and older adults, but sex-specific differences may exist according to different anthropometric or performance-based definitions.     

Tools in the Assessment of Sarcopenia

This review provides a framework for the development of an operational definition of sarcopenia and of the potential end points that might be adopted in clinical trials among older adults. While the clinical relevance of sarcopenia is widely recognized, there is currently no universally accepted definition of the disorder. The development of interventions to alter the natural history of sarcopenia also requires consensus on the most appropriate end points for determining outcomes of clinical importance which might be utilized in intervention studies. We review current approaches to the definition of sarcopenia and the methods used for the assessment of various aspects of physical function in older people. The potential end points of muscle mass, muscle strength, muscle power, and muscle fatigue, as well as the relationships between them, are explored with reference to the availability and practicality of the available methods for measuring these end points in clinical trials. Based on current evidence, none of the four potential outcomes in question is sufficiently comprehensive to recommend as a uniform single outcome in randomized clinical trials. We propose that sarcopenia may be optimally defined (for the purposes of clinical trial inclusion criteria as well as epidemiological studies) using a combination of measures of muscle mass and physical performance. The choice of outcome measures for clinical trials in sarcopenia is more difficult; co-primary outcomes, tailored to the specific intervention in question, may be the best way forward in this difficult but clinically important area.     

肌少症、骨质疏松症的关系及研究进展

随着人均寿命的延长,与肌肉骨骼系统相关疾病的发病率随之增长,国内外学者对肌少症、骨质疏松症的关注度也越来越高。肌少症是指与增龄相关的进行性、全身肌量减少和/或肌强度下降或肌肉生理功能减退。骨质疏松症是以骨量减少、骨组织显微结构退化为特征,以至骨的脆性增高及骨折危险性增加的一种全身性骨病。肌少症、骨质疏松症是危害老年人健康的病理状态,使得老年人的生活质量大打折扣,患有肌少症的人群免疫功能、日常生活能力较常人降低,感染风险、跌倒风险、致残率、死亡风险较常人增加,患有骨质疏松症的人群跌倒风险、骨折风险、致残率也较常人高很多。肌少症与骨质疏松症相互影响、紧密关联的机制比较复杂,包括肌肉收缩力学负荷对骨骼机械力的影响,以及肌肉与骨骼间复杂精密内分泌调控的生物学机制。针对两者之间存在的许多共同危险因素及发病机制,进行运动干预、营养指导、药物治疗,有助于延缓肌少症、骨质疏松症的进展,改善不良预后。本文将结合国内外研究对两者概念、发病机制、临床表现、评估标准、干预及治疗等之间的相关关系及研究进展进行一一综述。     

绝经后女性肌少症

肌少症为老龄化进展过程中以骨骼肌质量及力量下降为特征的临床综合征，并伴有残疾、生活质量降低甚至死亡，在老年人群中广泛存在，严重影响老年人的生活质量，是当今社会重要的公共健康问题。目前国际上关于肌少症的诊断及筛查方法尚未统一，多个组织先后制定了肌少症共识，提出肌少症的诊断切点，临床实践中使用握力、步速等方法来评估老年人肌肉情况。绝经是一种与年龄相关的生理状况，与自然衰退的雌激素水平相关，易导致肌肉质量和力量的降低，增加肌少症患病率。绝经后女性肌肉组织的质量、功能以及肌肉组织的成分发生变化与雌激素水平降低有关，还受营养、运动、环境、遗传等其他多种复杂因素影响，目前尚没有明确关于肌少症的治疗药物，但现有证据认为阻抗运动、膳食营养、性激素替代治疗等对于改善老年绝经后女性肌肉的质量及力量具有重要作用。目前绝经与肌少症的关系还处于探索阶段，仍有许多值得进一步研究的问题，本文就肌少症的诊断及绝经后激素变化和增龄与肌少症的关系等进行综述。     

Sarcopenia and osteopenia among 70–80-year-old home-dwelling Finnish women: prevalence and association with functional performance

Summary

This study showed that the prevalence of sarcopenia (low muscle mass and performance) among 70–80-year-old home-dwelling Finnish women is very low, while every third woman has WHO-based osteopenia (low bone mass). Muscle mass and derived indices of sarcopenia were not significantly related to measures of functional ability.

Introduction

This study aims to determine the prevalence of sarcopenia and osteopenia among four hundred nine 70–80-year-old independently living Finnish women. The study compared consensus diagnostic criteria for age-related sarcopenia recently published by the European Working Group on Sarcopenia in Older People (EWGSOP) and the International Working Group on Sarcopenia (IWG) and assessed their associations with functional ability.

Methods

Femoral bone mineral density and body composition were measured with dual-energy X-ray absorptiometry. Skeletal muscle mass index (SMI), gait speed, and handgrip strength were used for sarcopenia diagnosis. Independent samples t tests determined group differences in body composition and functional ability according to recommended diagnostic cutpoints. Scatter plots were used to illustrate the correlations between the outcome measures used for diagnosis.

Results

Prevalence of sarcopenia was 0.9 and 2.7 % according to the EWGSOP and IWG, respectively. Thirty-six percent of the women had WHO-based osteopenia. Women with higher gait speed had significantly lower body weight and fat mass percentage, higher lean mass percentage, and better functional ability. Women with a low SMI weighed significantly less, with no significant differences in other outcome measures. SMI, gait speed, and grip strength were significantly correlated.

Conclusions

Our study suggests that when using consensus definitions, sarcopenia is infrequent among older home-dwelling women while every third woman has osteopenia. In clinical practice, attention should be paid to the decline in functional ability rather than focusing on low muscle mass alone.     

肌少-骨质疏松症专家共识

肌少-骨质疏松症已成为全球性的公共健康问题和前沿研究难题。目前仍存在对肌少-骨质疏松症的临床知晓率低、重视不够、诊断治疗方法单一、管理不完善等实际问题。中国健康促进基金会组织专家编写《肌少-骨质疏松症专家共识》,为肌少-骨质疏松症的临床诊疗和科学研究提供参考。共识论述了肌少-骨质疏松症是肌少症和骨质疏松症并存的退行性代谢综合征,有共同的发病基础,诊断标准应是骨质疏松症与肌少症并存,预防比治疗更重要。肌少-骨质疏松症的治疗目标是改善肌量、肌力、身体平衡、骨量和骨质量,避免出现跌倒和骨折。肌少-骨质疏松症的管理应肌骨并重,综合诊断、规范治疗,医患合作,建立科学评估、定期随访机制。