[Association of sleep duration and risk of frailty among the elderly over 80 years old in China: a prospective cohort study].

Objective: To explore the association between sleep duration and the risk of frailty among the elderly over 80 years old in China. Methods: Using the data from five surveys of the China Elderly Health Influencing Factors Follow-up Survey (CLHLS) (2005, 2008-2009, 2011-2012, 2014, and 2017-2018), 7 024 elderly people aged 80 years and above were selected as the study subjects. Questionnaires and physical examinations were used to collect information on sleep time, general demographic characteristics, functional status, physical signs, and illness. The frailty state was evaluated based on a frailty index that included 39 variables. The Cox proportional risk regression model was used to analyze the correlation between sleep time and the risk of frailty occurrence. A restricted cubic spline function was used to analyze the dose-response relationship between sleep time and the risk of frailty occurrence. The likelihood ratio test was used to analyze the interaction between age, gender, sleep quality, cognitive impairment, and sleep duration. Results: The age M (Q1, Q3) of 7 024 subjects was 87 (82, 92) years old, with a total of 3 435 (48.9%) patients experiencing frailty. The results of restricted cubic spline function analysis showed that there was an approximate U-shaped relationship between sleep time and the risk of frailty. When sleep time was 6.5-8.5 hours, the elderly had the lowest risk of frailty; Multivariate Cox proportional risk regression model analysis showed that compared to 6.5-8.5 hours of sleep, long sleep duration (>8.5 hours) increased the risk of frailty by 13% (HR: 1.13; 95%CI: 1.04-1.22). Conclusion: There is a nonlinear association between sleep time and the risk of frailty in the elderly.目的： 探讨中国80岁及以上高龄老人睡眠时间与虚弱发生风险间的关联。 方法： 采用中国老年健康影响因素跟踪调查（CLHLS）五次（2005、2008—2009、2011—2012、2014和2017—2018年）调查数据，以年龄80岁及以上的7 024名高龄老人为研究对象。采用问卷调查和体格检查收集睡眠时间、一般人口学特征、功能状态、体征、患病情况等信息，基于包括39个变量的虚弱指数评估虚弱状态，Cox比例风险回归模型分析睡眠时间与虚弱发生风险的关联，采用限制性立方样条函数分析睡眠时间与虚弱发生风险的剂量-反应关联，采用似然比检验分析年龄、性别、睡眠质量、认知功能受损与睡眠时间的交互作用。 结果： 7 024名研究对象年龄M（Q1，Q3）为87（82，92）岁，共计3 435人（48.9%）发生虚弱。限制性立方样条函数分析结果显示，睡眠时间与虚弱发生风险呈近似“U”型关系，在睡眠时间为6.5~8.5 h时，高龄老人的虚弱发生风险最低；多因素Cox比例风险回归模型分析结果显示，与6.5~8.5 h睡眠时间相比，长睡眠时间（>8.5 h）将增加13%的虚弱发生风险（HR：1.13；95%CI：1.04~1.22）。 结论： 高龄老人睡眠时间与虚弱发生呈非线性关联。.