Aging's double trouble: Frailty and social isolation deepen health risks

By Hugo Francisco de SouzaReviewed by Susha Cheriyedath, M.Sc.Mar 6 2024

In a recent review published in the journal The Lancet Healthy Longevity, researchers collated the outcomes of 130 observational studies exploring the bi-directional associations between frailty and social vulnerability, rising concerns in today’s unnaturally long-lived human society.

Their findings present that both frailty (reduced physiological reserve) and social vulnerability (insufficient social interactions, support, or connections) worsen with increasing age and are independently associated with adverse outcomes, including heightened risk or intensity of the other. When present together, these conditions result in a significantly increased decline in physical and cognitive function and mortality risk. This review aims to inform clinicians and public health policymakers to account for both frailty and social vulnerability when attempting to manage either.

Study: The relationship between frailty and social vulnerability: a systematic review. Image Credit: Paul Maguire / Shutterstock

What is frailty, and how is it related to social vulnerability?

Frailty is theoretically defined as a clinically recognizable state of increased vulnerability resulting from aging-associated declines in physiological reserve and function across multiple systems. This compromises the ability to cope with everyday or acute stressors. Frailty is a common condition among older individuals and is a growing global clinical and public health concern. Advances in modern medicine have substantially improved human life expectancy beyond natural limits—1.5 billion people are expected to be 65 years or older by 2050, resulting in a corresponding increase in frailty prevalence.

Research has shown that frailty can significantly increase risks of mortality, functional decline (including loss of independence), and associated medical expenses. Alarmingly, frailty is being increasingly observed as comorbidity alongside social vulnerability, the deficiency of adequate social interaction, connection, or support. Like frailty, social vulnerability is age-associated, conferring upon the latter the same longevity-related demerits that plague the former.

Unfortunately, despite frailty and social vulnerability representing distinct constructs with differing pathologies, most conventional diagnostic models (e.g., the frailty index, the Fried frailty phenotype, and the social vulnerability index) operationalize both conditions, confounding research into the associations between these comorbidities. Reviews aimed at interpreting these results suffer from the shared con of only focusing on a single social vulnerability concept (e.g., loneliness or social isolation) and its association with frailty, thereby reducing their holistic outlook and generalizability.

About the study

The present review has three main aims: 1. To investigate the prevalence of social vulnerability in individuals displaying frailty and vice versa; 2. To evaluate the longitudinal, potentially bidirectional association between frailty and social vulnerability; and 3. To estimate the impacts and outcomes of the combinations of these conditions. The review is registered under the International Prospective Register of Systematic Reviews (PROSPERO, CRD42023425870), and its methodology was designed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Data (publications) for the study were obtained from six online scientific repositories (MEDLINE, Scopus, Web of Science Core Collection, PsycINFO, and the Cumulative Index to Nursing and Allied Health Literature) from January 1, 2021 (due to being the year wherein frailty was first qualitatively described) to April 28, 2023. Of the 4,083 articles initially identified, 1,413 were found to be duplicates, and 2,189 were removed during title and abstract screening, resulting in a full-text screening set of 481 publications. Applying study inclusion criteria (participant age >18 years; measures both frailty and social vulnerability; was of either longitudinal or cross-sectional study design) resulted in the further exclusion of 359 publications, leaving a final dataset of 130 included studies.

A piloted template was used for publication data extraction, and five independent reviewers manually conducted the Joanna Briggs Institute critical appraisal checklist for risk of bias assessment and quality assessment. Results were generated and discussed in the form of a narrative synthesis, with harvest plots used for descriptive data presentation.

Study findings

The 130 included studies comprised 100 sample datasets, with some sample cohorts like the Survey for Health, Ageing, and Retirement in Europe (SHARE), the China Health and Retirement Longitudinal Study (CHARLS), and the English Longitudinal Study of Ageing (ELSA) cohorts analyses in multiple independent studies. Study-specific sample cohorts were found to range in size from 70 to 27,468 individuals, representing individuals from 27 countries between the ages of 40 and 85 years.

“Of the selected studies, 90 assessed the cross-sectional relationship between frailty and social vulnerability, 36 assessed longitudinal changes in these constructs, and 23 assessed the relationship between these constructs and clinical outcomes.”

While quality assessment revealed a generally high publication quality, some studies required substantial adjustments for confounding variables due to standardized variables not being reported. Analyses of cross-sectional associations revealed that frailty may be more commonly associated with social vulnerability than expected – 23 out of 24 studies associated frailty with increased loneliness, nine of 10 with reduced social participation, and all eight included studies with increased social vulnerability index values.

The adverse outcomes of frailty extend beyond just these, with 20 of 23 studies finding frailty associated with increased social isolation, 19 of 28 with reduced perceived social support, and 12 of 14 with social frailty. Alarmingly, some studies found an association between social and physical frailty (11 of 14).

Social vulnerability assessments painted a similar picture, with each individual social vulnerability component associated with a heightened risk of frailty and hastening of condition progression in individuals with pre-existent frailty. Assessing the outcomes of the combined effects of frailty and social vulnerability revealed that when present in combination, these conditions substantially increase patients’ mortality risk and observable declines in their physical and cognitive functionality.

Conclusion

The present review collates and discusses data and results from 130 publications investigating the associations between frailty and social vulnerability. Their findings highlight that these conditions, while distinct in their symptoms and pathologies, are closely interrelated. The presence of either condition dramatically increases the risk of acquiring the other. In individuals displaying both frailty and social vulnerability, the persistence of either condition is observed to hasten the progression of the other. Alarmingly, individuals presenting booth conditions were found to depict significantly higher mortality risks and physical and cognitive functional declines than those with only one of the conditions under study.

These findings will help clinicians and policymakers make more informed decisions when attempting to target frailty or social vulnerability. Simultaneous interventions against both are expected to produce the best outcomes for either.