Abstract: Frailty index has been widely used to study the speed of change in frailty among older adults, and to depict the dynamic process of frailty caused by aging in recent years. Taking life course perspective as theoretical background, this study emphasizes the implications of observing and understanding the frailty trajectory within cohort, and also assumes that a framework for understanding the intra-cohort pattern of frailty should have three essential properties: random variability, trajectory heterogeneity, and cumulative disadvantage. Furthermore, relating these three properties to the specific parameters for growth curve models, datasets from China Longevity and Heath Longitudinal Survey is applied to test them. The primary results indicate that frailty trajectory follows a Ushaped curve, but there is significant betweenperson variation, and withingroup rather than between-group cumulative disadvantage mainly explains how the frailty trajectory differentiates.

Keywords: Frailty Index, Growth Curve Model, Cumulative Disadvantage, Life Course Perspective

摘要： 虚弱指数近年来被广泛应用于研究老年人的健康和虚弱变化速度，以刻画老化引起的虚弱程度的动态过程。基于生命历程视角，文章强调从队列内认识和理解虚弱轨迹变化的意义，认为一个合适的理解队列内虚弱指数变化轨迹模式的框架应当满足3个重要属性：随机变异、轨迹分化与累积劣势。进一步，将此3个重要属性整合到增长曲线模型中，赋予参数具体含义，运用中国老年人健康长寿影响因素跟踪调查数据加以考察。初步分析结果表明：中国老年人虚弱程度随着年龄推移加速上升，但这种加速上升态势在超高龄老年人中消失了；中国老年人虚弱变化轨迹存在明显的分化，这种分化背后隐含着累积劣势机制，不过，其主要体现为组内而非组间累积劣势。

关键词: 虚弱指数, 增长曲线模型, 累积劣势, 生命历程视角