Abstract: Background　The risk of falls increases with age-related gradual decline in physical functions，sleep quality and physical responsiveness as well as increase in frailty，which has become a focus of various scholars.Objective　To explore the chain mediating effect of frailty and sleep quality on the relationship between family support and fall risk of rural elderly people.Methods　From August 2019 to April 2020，the rural elderly in 15 villages of Xiaoji Town，Fengnan District，Tangshan City received a household survey with a questionnaire consisting of parts of self-designed demographics，PSS-Fa，Fried frailty index，PSQI and modified FROP-Com.The questionnaires were handed in immediately after being completed by older people with functional independence or by investigators based on the results of interviews with older people without abilities to complete independently.Pearson correlation analysis and mediation model were used to explore the chain mediating effect of frailty and sleep quality on the relationship between family support and fall risk.Results　The survey obtained a response rate of 96.6%（1 498/1 550）.The average scores of PSS-Fa，Fried frailty index，PSQI and modified FROP-Com were （9.0±2.0） （2.2±1.5） （7.1±4.0） （6.5±5.8），respectively.The average scores of PSS-Fa，Fried frailty index，or modified FROP-Com differed significantly by sex，age and education level as well as marital status （P<0.05）.The average scores of PSQI differed significantly by sex，age and education level（P<0.05）.The score of PSS-Fa was negatively correlated with that of Fried frailty index，PSQI or modified FROP-Com （r=-0.197，-0.113，-0.266，P<0.05）.The scores of Fried frailty index was positively correlated with that of PSQI or modified FROP-Com （r=0.284，0.577，P<0.05）.PSQI score was positively correlated with the score of modified FROP-Com （r=0.319，P<0.05）.Path analysis showed that family support had a negative impact on frailty （β=0.17，P<0.001） and sleep quality （β=0.11，P<0.001）.Good sleep quality had a positive impact on frailty（β=0.27，P<0.001） and risk of falls（β=0.53，P<0.001）.Frailty was associated with increased risk of falls （β=0.53，P<0.001）.Bias-corrected bootstrap revealed that the estimated effect size of frailty in the path of "family support → frailty→ fall risk" was -0.257〔95%CI（-0.340，-0.176）〕，indicating that frailty played a partial medicating role between family support and fall risk.The estimated effect size of sleep quality was -0.055〔95%CI（-0.089，-0.029）〕in the path of "family support → sleep quality → fall risk"，indicating that sleep quality played a partial medicating role between family support and fall risk.The estimated effect size of “sleep quality →frailty” was -0.046〔95%CI（-0.070，-0.020）〕in the path of "family support →sleep quality →frailty→ fall risk"，indicating that sleep quality and frailty played a chain mediating role in the relationship between family support and fall risk.Conclusion　Frailty and sleep quality may have chain mediating effect on the relationship between family support and fall risk in rural elderly people.Therefore，slowing down the process of frailty and improving sleep quality may be conducive to reducing the risk of falls and improving the quality of life.

Key words: Marasmus, Sleep, Accidental falls, Family support, Aged, Chain mediating effects

摘要： 背景　随着年龄的增大，老年人身体功能不断下降，衰弱发生率逐渐升高，睡眠质量越来越差，身体反应能力下降，从而增加老年人跌倒风险，已成为学界关注的重点。目的　探讨衰弱和睡眠质量对农村老年人家庭支持和跌倒风险的链式中介作用。方法　2019年8月—2020年4月，对唐山市丰南区小集镇15个村庄的农村老年人进行调查。采用调查问卷进行入户调查，能自行填写调查问卷的老年人独立完成，不能自行填写者由调查员就调查内容与其交谈，然后根据其意愿填写，问卷当场回收。调查问卷包括一般资料调查表、家庭支持量表（PSS-Fa）、Fried衰弱指数、匹兹堡睡眠质量指数（PSQI）、修订版社区老年人跌倒危险评估工具（修订版FROP-Com）。采用Pearson相关分析、中介模型探究衰弱和睡眠质量对农村老年人家庭支持和跌倒风险的链式中介作用。结果　共发放调查问卷1 550份，回收有效问卷1 498份，有效回收率为96.6%。农村老年人PSS-Fa、Fried衰弱指数、PSQI、修订版FROP-Com得分分别为（9.0±2.0）（2.2±1.5）（7.1±4.0）（6.5±5.8）分。不同性别、年龄、文化程度的农村老年人PSS-Fa、Fried衰弱指数、PSQI、修订版FROP-Com得分比较，差异有统计学意义（P<0.05）；不同婚姻状况的农村老年人PSS-Fa、Fried衰弱指数、修订版FROP-Com得分比较，差异有统计学意义（P<0.05）。农村老年人PSS-Fa得分与Fried衰弱指数、PSQI、修订版FROP-Com得分均呈负相关（r值分别为-0.197、-0.113、-0.266，P值均<0.05）；Fried衰弱指数得分与PSQI、修订版FROP-Com得分均呈正相关（r值分别为0.284、0.577，P值均<0.05）；PSQI得分与修订版FROP-Com得分呈正相关（r=0.319，P<0.05）。路径分析表明，农村老年人家庭支持对衰弱具有负向影响（β=-0.17，P<0.001），对睡眠质量具有负向影响（β=-0.11，P<0.001）；睡眠质量对衰弱具有正向影响（β=0.27，P<0.001），对跌倒风险具有正向影响（β=0.32，P<0.001）；衰弱对跌倒风险具有正向影响（β=0.53，P<0.001）。采用偏差矫正Bootstrap检验模型分析中介效应的有效性，结果显示，“家庭支持→衰弱→跌倒风险”路径中，衰弱的估计值为-0.257〔95%CI（-0.340，-0.176）〕，表明衰弱在家庭支持和跌倒风险的部分中介效应成立；“家庭支持→睡眠质量→跌倒风险”路径中，睡眠质量的估计值为-0.055〔95%CI（-0.089，-0.029）〕，表明睡眠质量在家庭支持和跌倒风险的部分中介效应成立；“家庭支持→睡眠质量→衰弱→跌倒风险”路径中，睡眠质量→衰弱的估计值为-0.046〔95%CI（-0.070，-0.020）〕，表明睡眠质量与衰弱在家庭支持和跌倒风险的链式中介效应成立。结论　衰弱和睡眠质量对农村老年人家庭支持和跌倒风险具有链式中介作用，因此减缓衰弱进程、提高睡眠质量有利于降低农村老年人跌倒风险，提高农村老年人生活质量。

关键词: 衰弱, 睡眠, 意外跌倒, 家庭支持, 老年人, 链式中介作用