With the emergence of diseases, people become frailer and are expected to be less tolerant of adverse outcomes. Frailty was first described to explain the variability in life expectancy in individuals of the same age. Nowadays, it is described as a syndrome and as a state. It is used to explain the heterogeneity of people not only in their responses to biological ageing but also in their responses to illness. In this review, we explore the role of frailty both in age-related diseases, including dementia, cancer and cardiovascular disease, and in non-age-related diseases, such as Human Immunodeficiency Virus. We describe how high levels of frailty in such disorders predict worse outcomes and play a direct role in disease progression and in prognostic prediction. Overall, the potential for frailty to predict adverse health outcomes among young people as well as in non-age-related diseases is an evolving topic. Understanding how frailty contributes to poor health and how it can be modified to prevent or delay disease progression will ultimately enhance quality of life in affected individuals.

中文翻译：

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脆弱-一种评估疾病脆弱性的有前途的概念。

随着疾病的出现，人们变得虚弱，并且人们对不良后果的容忍度也降低了。首先描述了脆弱，以解释同一年龄个体的预期寿命的差异。如今，它被描述为一种综合症和一种状态。它不仅可以用来解释人们对生物衰老的反应，还可以解释人们对疾病的反应的异质性。在这篇综述中，我们探讨了衰弱在与年龄有关的疾病（包括痴呆症，癌症和心血管疾病）以及与年龄无关的疾病（如人类免疫缺陷病毒）中的作用。我们描述了在这种疾病中高水平的身体虚弱如何预测较差的结果，并在疾病进展和预后预测中起直接作用。总体，预测年轻人以及与年龄无关的疾病对健康不利的虚弱潜力是一个不断发展的话题。了解体弱如何导致健康不良以及如何对其进行预防或延缓疾病进展将最终提高受影响个体的生活质量。