老年人群中常见一种包括跌倒、失能、认知障碍、自主活动减少、非自主体重下降以及疲劳等系列临床症状的 综合状态，通常与特定疾病状态无关，被称为“虚弱症（frailty）”。虚弱症是营养不良的主要表现之一，又与肌肉减少症 有本质的不同，虚弱症是患者整体机能的减退，并不完全与骨骼肌的数量减少或功能减退有关。虚弱症患者的神经、肌肉、 代谢和免疫系统的生理储备下降，抗应激能力减退，其不良临床结局包括并发症增多、意外伤害（如跌倒或骨折）、残疾、 生活质量差甚至死亡等。虚弱症常见于老年人群、肿瘤、心血管和呼吸系统等疾病患者、营养不良人群等。不同报道显示 老年人群患病率为 4.0%~59.1%，且随年龄增加。虚弱症可通过核心症候群（表型）或虚弱指数进行诊断。虚弱评估可以提 供额外的有价值的预后判断指标，尽早评估并干预，对改善预后有重要意义。维持个体内在的稳态平衡比治疗某个疾病可 能获益更大，改善营养、加强锻炼、制定个体化多因素干预模式是预防虚弱症患者不良临床结局的最好方法。本文对虚弱 症的定义与诊断、流行病学、病因与病理机制以及干预措施等进行了综述。

A cluster of symptoms including falls, disability, cognitive impairment, decreased autonomic activity, unwilled weight loss and fatigue are common in older people, and together this “core symptom complex” defines frailty. Frailty is often related to malnutrition, but is distinguished by the presence of sarcopenia. Frailty embodies the decline in a patient’s overall function, which is not entirely explained by a loss of skeletal muscle mass or decreases in muscle function. Frailty occurs when the individual’s physiological reserve decreases in conjunction with internal dynamic balance disorders and physiological debility. Frailty is associated with adverse clinical outcomes including an increased risk of complications of other conditions and surgery, unintentional injury (falls and fractures), disability, a poor quality of life, and even death. Frailty is common not only in the elderly, but also in patients with cancer, cardiovascular diseases, respiratory diseases, and malnutrition. The prevalence of frailty has been reported to be between 4.0%~59.1% in different reports, and increases with age. Frailty can be diagnosed by the presence of the core symptom complex (frailty phenotype) or based on the frailty index (FI). Early assessment and treatment can significantly improve the health prognosis of patients. Treatments aimed at maintaining an individual's homeostasis can be more beneficial to preventing or resolving frailty than treating the underlying disease alone. Improving the patient’s nutritional status, implementing physical exercise, and developing individualized multidisciplinary interventions may be the best ways to prevent adverse clinical outcomes in patients with frailty. This article reviews the definitions, diagnosis, epidemiology, etiology and pathogenesis of frailty, as well as the interventions that can be used to combat frailty.