The Association Between Social Isolation And Frailty And Frailty Transitions

Background: Frailty has become a significant challenge faced by the global public health with the rapid growth of the elderly population.Frailty is a state characterized by increased vulnerability of the body systems due to internal or external stressors,and it is widely associated with an increased risk of adverse health outcomes in older adults.China,with the world’s largest older population,has seen limited representative studies on frailty and the transition characteristics of frailty states in Chinese older adults.Moreover,accumulating studies have indicated that frailty is not a steady state but a dynamic process where improvement is possible,particularly in its early stages.Although frailty appears to be reversible,a complete remission becomes an increasingly rare event in the absence of an intervention.Worsening in frailty is a common frailty transition,and older people who are frail at baseline are more likely to die.Identifying and targeting the prognostic factors which might speed or mitigate the passage from non-frail,pre-frail,frail,and to death could aid specific clinical and personal decision-making regarding timing and types of intervention to warrant the effectiveness in managing the frail old.However,research on the transitions of frailty status over time remains scarce.Additionally,previous frailty research predominantly focused on physical frailty,while emerging studies have shown that frailty induced by social factors significantly compromises the health of older populations.Social isolation is a crucial component of this,referring to a significant reduction in social connections based on indicators such as reduced social networks,low engagement in social activities,lack of social support,and living alone.Globally,up to 50% of older adults are at risk of social isolation,yet limited evidence suggests its association with subsequent increased risks of frailty and frailty-related mortality.Objectives: This study aimed to quantify the association between social isolation and different progressions and outcomes of frailty in a representative sample of Chinese older adults.Methods: The samples for this study were 8,134 older persons from the Hubei Memory and Aging Cohort Study(HMACS)and 12,936 aging individuals from the Chinese Longitudinal Healthy Longevity Survey(CLHLS),which were established by Wuhan University of Science and Technology and by Peking University,respectively.Frailty was defined using the frailty index(FI),analyzed continuously and as three categories of non-frail(≤0?08),pre-frail(>0?08 to <0?25),or frail(≥0?25 to 1·00).Social isolation index(SII)was screened by a complex scale that assessing social participating,relationship,and support of participants.Markov statetransition models were used to study annual transitions among non-frailty,prefrailty,frailty,and mortality.Multi-state model was used to analyze the impact of social isolation on different progressions of frailty.Cumulative transition probabilities of different stages of frailty under different frailty levels were estimated,adjusted for confounders.Results:(1)Of 8,134 participants from HMACS,58.1% had no frailty,38.0% were in a pre-frail state,and 3.7% were frail.Factors associated with increased risk of prefrailty and frailty included increasing age(Odds ratio [OR] = 1.046,95% CI: 1.037 ～1.054;OR = 1.082,95% CI: 1.061 ～ 1.103),female gender(OR = 2.441,95% CI:2.155 ～ 2.766;OR = 4.756,95% CI: 3.472 ～ 6.513),residing in rural areas(OR =1.235,95% CI: 1.081 ～ 1.411;OR = 1.569,95% CI: 1.111 ～ 2.215),illiteracy(OR =1.664,95% CI: 1.449 ～ 1.911;OR = 1.467,95% CI: 1.085 ～ 1.982),income instability(OR = 1.179,95% CI: 1.010 ～ 1.375;OR = 3.314,95% CI: 2.497 ～ 4.399),smoking(OR = 1.313,95% CI: 1.147 ～ 1.503;OR = 3.308,95% CI: 2.390 ～ 4.579),alcohol consumption(OR = 1.353,95% CI: 1.199 ～ 1.527;OR = 3.325,95% CI:2.493 ～ 4.433),physical inactivity(OR = 1.161,95% CI: 1.037 ～ 1.299;OR = 1.357,95% CI: 1.046 ～ 1.760),and social isolation(OR = 1.080,95% CI: 1.045 ～ 1.117;OR= 1.348,95% CI: 1.248 ～ 1.457).A positive correlation was observed between SII and FI(β = 0.006,95% CI: 0.005 ～ 0.007).There was a non-linear relationship between SII and FI,with higher SII associated with an increased risk of pre-frailty and frailty(OR = 1.080,95% CI: 1.045 ～ 1.117;OR = 1.348,95% CI: 1.248 ～ 1.457).(2)Among 12,936 participants from CLHLS followed up for a median of 10 years,we found that the likelihood of transitioning from frailty to death was 5.5 times that of transitioning from pre-frailty to death and 25.2 times that of transitioning from no frailty to death.Additionally,for individuals with no frailty,each one-point increase in SII was associated with a 5.4% increased risk of transitioning to pre-frailty(Hazard ratio [HR] = 1.054,95% CI: 1.004 ～ 1.107)and a 22.5% increased risk of transitioning to death(HR = 1.225,95% CI: 1.015 ～ 1.478).For individuals in a prefrail state,each one-point increase in SII was associated with a 4.7% increased risk of transitioning to frailty(HR = 1.047,95% CI: 1.002 ～ 1.094)and an 11.5% increased risk of transitioning to death(HR = 1.115,95% CI: 1.043 ～ 1.192).For frail individuals,each one-point increase in SII was associated with a 10.9% increased risk of transitioning to death(HR = 1.109,95% CI: 1.076 ～ 1.142).Conclusions: Frailty is a serious issue among Chinese elderly individuals,and the factors associated with frailty are numerous and complex.The study highlights a significant association between social isolation and an increased risk of pre-frailty and frailty in cross-sectional analysis.Moreover,longitudinal findings over a ten-year period emphasize the vital role of social isolation in the progression of frailty among the elderly.Overall,these research findings underscore the substantial impact of social factors on the frailty status of older adults,providing robust evidence for the development of relevant intervention measures.Assisting older adults in establishing stronger social connections and support systems may contribute to the prevention and alleviation of frailty,ultimately enhancing their quality of life and health.