How does social support interact with intrinsic capacity to affect the trajectory of functional ability among older adults? Findings of a population-based longitudinal study

Trajectories of intrinsic capacity decline and related factors in old persons: A 15-year community-based cohort study in Beijing

BACKGROUND

Intrinsic capacity (IC) is vital to the World Health Organization's healthy ageing framework. This study aims to develop an IC assessment model, and identify its longitudinal trajectories and related factors in old persons.

METHODS

This was a 15-year three-wave prospective cohort study of the 10/66 dementia series researches in Beijing, China. Totally 2 156 community-dwelling old persons aged 65 years and over were included at baseline to develop an IC assessment model, with 474 completing follow-up surveys for IC trajectory identification. IC was assessed using 11 items of the five domains and bifactor-multidimensional item response theory model. The group-based trajectory model and multivariate logistic regression model were employed to identify longitudinal trajectories and related factors of IC.

RESULTS

Three IC trajectories were identified as low baseline IC with rapid descending trajectory (11.39%), medium baseline IC with moderate descending trajectory (75.53%), and high baseline IC with slight descending trajectory (13.08%). Compared to the "slight descending trajectory", aged 75 years and over (aOR: 9.48), female (aOR: 4.75), and unmarried/non-cohabiting (aOR: 4.73) were positively associated with the "rapid descending trajectory". Completed secondary school/higher education (aOR: 0.08; aOR: 0.27), more vegetables/fruits intake (aOR: 0.91; aOR: 0.94), and private restricted support network (aOR: 0.17; aOR: 0.37) were negatively associated with the "rapid descending trajectory" and "moderate descending trajectory".

CONCLUSIONS

Community-dwelling old persons in Beijing exhibit three IC trajectories, with the majority showing moderate descending trajectory. Interventions should address gender or education inequities and modifiable factors like diet and social support to mitigate IC decline.

Implications of intrinsic capacity subtypes for post-PCI patients older than 45

We aim to explore the contributing factors to intrinsic capacity (IC) in middle-aged and older patients after percutaneous coronary intervention (PCI). Intrinsic capacity comprises six core domains: cognition, locomotion, vitality, psychology, vision, and hearing. Each domain was assessed in detail using different scales, based on which the composite IC score was calculated. The study employed latent class analysis (LCA) to identify the various IC subtypes. Logistic regression analyses were used to determine the effect variables of IC subtypes. 318 middle-aged and older post-PCI patients filled out the assessments. Three distinct IC subtypes were found: 47.8% poor audition-vision group (class 1), 38% high cognition-psychology group (class 2), and 14.2% low locomotion-vitality group (class 3). The IC subtype classification may be impacted by factors such as cTnI, NT proBNP, cardiac function, exercise frequency, and comorbidities. Examining IC subtypes may be helpful for focused intervention, and further empirical research is still needed to determine their drivers.

Intrinsic Capacity and Instrumental Activity of Daily Living Among Community Dwelling Elderly in China: The Mediating Effect of Two-Way Social Support and Sense of Coherence

OBJECTIVES

To explore the influence of intrinsic capacity (IC) on instrumental activities of daily living (IADL) among community-dwelling elderly and to analyze the chain-mediated effects of two-way social support, and sense of coherence (SOC).

DESIGN

This study was a cross-sectional research design. Participants were recruited from September 2023 to December 2023 from Hangzhou City, Zhejiang Province, China, using a multistage sampling method.

SAMPLE

Participants in this study were at least 60 years old and had been currently living in the community for at least 1 year (n = 458).

MEASUREMENTS

The Integrated Care for Older People screening tool, the Brief Two-Way Social Support Scale, the Sense of Coherence Scale-13, and the Functional Activities Questionnaire were used to collect relevant data, which were statistically tested using structural equation modeling and multiple mediation effects.

RESULTS

There were correlations between IC, two-way social support, SOC and IADL in community-dwelling elderly (all p < 0.01). IC predicted two-way social support (β = 0.570, p < 0.001), SOC (β = 0.544, p < 0.001) and IADL (β = -0.492, p < 0.001); two-way social support had a positive predictive effect on SOC (β = 0.363, p < 0.001) but a negative predictive effect on IADL (β = -0.193, p < 0.001); SOC negatively predicted IADL (β = -0.150, p < 0.05).

CONCLUSIONS

To mitigate the impact of declining IC on IADL among community-dwelling elderly, to sustain independent living, and to reduce the risk of progression to illness and disability, this study proposes two-way social support and SOC as potential effective intervention targets. This conclusion holds implications for the assessment and intervention of elderly health, as well as the formulation of public health policies.

The effect of the interaction between intrinsic capacity and social support on the trajectories of activities of daily living in older adults

OBJECTIVES

This study explored the effect of the interaction between intrinsic capacity and social support on the activities of daily living in the older adults.

METHODS

A total of 3,124 older adults participated in the study. Data on the assessment of intrinsic capacity as well as activities of daily living (ADL) and social support were collected. The latent growth curve model (LGCM) was used to examine the effect of the interaction between social support and intrinsic capacity on the activities of daily living in the older adults.

RESULTS

A total of 3,730 older adults were included at baseline, and 3,124 older adults completed the 4-year follow-up. The ADL score of the older adults showed a significant downward trend with time over 4 years (β=-0.115, P<0.05). In the elderly population with high intrinsic capacity, the ADL of individuals with low levels of social participation decreased significantly over time (β=-0.114, P=0.012). In the elderly group with low intrinsic capacity, the ADL of individuals with low levels of social participation (β=-0.245, P=0.005) and high levels of life care (β=-0.167, P=0.001) decreased significantly over time.

CONCLUSION

This is the first longitudinal study to explore the effects of interactions among intrinsic capacity, social participation and family support on the trajectory of ADL in the older adults from the perspective of the life course. Social participation can effectively improve functional ability of older adults with low intrinsic capacity. Life care is beneficial for maintaining the functional ability of older adults with intact intrinsic capacity, but it accelerates the deterioration of the functional ability of older adults with low intrinsic capacity.

Does Social Support Moderate the Relationship Between Frailty and Functional Ability Trajectory Among Community-Dwelling Older Adults?

BACKGROUND

Functional ability is the important prerequisite to live independently and achieve aging in place, which depends on the complex interaction of intrinsic and extrinsic factors. Identifying the trends and influencing factors of functional ability would contribute to the accurate assessment and intervention of geriatric health. This study aimed to disentangle the moderating effect of 3 types of social support, namely objective support, subjective support, and support utilization, on the relationship between frailty and functional ability trajectories.

METHODS

This was a secondary analysis using data from a prospective 3-wave study with a sample of 777 Chinese community-dwelling older adults. Social support was assessed using the Social Support Rating scale. Frailty was assessed using the FRAIL scale. Functional ability was measured by the Lawton Instrumental Activities of Daily Living scale. Latent growth curve models were implemented to test their relationships.

RESULTS

Objective support but not subjective support or support utilization moderated on the relationship between frailty and functional ability slope. Functional ability decline over time was buffered by objective support among robust individuals but exacerbated among (pre)frail individuals.

CONCLUSIONS

The moderating effect of social support on the relationship between frailty and functional ability trajectory varies by support types, which reminded that social support may be a promising intervention target to maintain functional independence for frail individuals, opening up a new perspective on social support in the field of disability prevention. Effective interventions should particularly address objective support in conjunction with empowering the frail older population to optimize the trajectory of functional ability.

Association of intrinsic capacity with functional decline and mortality in older adults: a systematic review and meta-analysis of longitudinal studies

BACKGROUND

Together with environmental factors, intrinsic capacity (the composite of all the physical and mental capacities of an individual) has been proposed as a marker of healthy ageing. However, whether intrinsic capacity predicts major clinical outcomes is unclear. We aimed to explore the association of intrinsic capacity with functional decline and mortality in older adults.

METHODS

In this systematic review and meta-analysis, we conducted a systematic search in MEDLINE (via PubMed), Scopus, and Web of Science from database inception to Feb 14, 2024, of observational longitudinal studies conducted in older adults (age ≥60 years) assessing the association of intrinsic capacity with impairment in basic activities of daily living (BADL) or instrumental activities of daily living (IADL) or risk of mortality. Estimates were extracted by two reviewers (JLS-S and W-HL) and were pooled using three-level meta-analytic models. The quality of each study was independently assessed by two authors (JLS-S and PLV) using the Newcastle-Ottawa Scale for longitudinal studies. Heterogeneity was evaluated using the I2 indicator at two levels: within-study (level 2) and between-study (level 3) variation. For associations between intrinsic capacity and IADL and BADL, we transformed data (standardised β coefficients and odds ratios [ORs]) into Pearson product moment correlation coefficients (r) using Pearson and Digby formulas to allow comparability across studies. For associations between intrinsic capacity and risk of mortality, hazard ratios (HRs) with 95% CIs were extracted from survival analyses. This study is registered with PROSPERO, CRD42023460482.

FINDINGS

We included 37 studies (206 693 participants; average age range 65·3-85·9 years) in the systematic review, of which 31 were included in the meta-analysis on the association between intrinsic capacity and outcomes; three studies (2935 participants) were included in the meta-analysis on the association between intrinsic capacity trajectories and longitudinal changes in BADL or IADL. Intrinsic capacity was inversely associated with longitudinal impairments in BADL (Pearson's r -0·12 [95% CI -0·19 to -0·04]) and IADL (-0·24 [-0·35 to -0·13]), as well as with mortality risk (hazard ratio 0·57 [95% CI 0·51 to 0·63]). An association was also found between intrinsic capacity trajectories and impairment in IADL (but not in BADL), with maintained or improved intrinsic capacity over time associated with a lower impairment in IADL (odds ratio 0·37 [95% CI 0·19 to 0·71]). There was no evidence of publication bias (Egger's test p>0·05) and there was low between-study heterogeneity (I2=18·4%), though within-study (I2=63·2%) heterogeneity was substantial.

INTERPRETATION

Intrinsic capacity is inversely associated with functional decline and mortality risk in older adults. These findings could support the use of intrinsic capacity as a marker of healthy ageing, although further research is needed to refine the structure and operationalisation of this construct across settings and populations.

FUNDING

None.

TRANSLATIONS

For the Spanish and French translations of the abstract see Supplementary Materials section.

Intrinsic capacity trajectories, predictors and associations with care dependence in community-dwelling older adults: A social determinant of health perspective

AIMS

To identify intrinsic capacity trajectories, predictors of intrinsic capacity trajectories and associations between intrinsic capacity trajectories and care dependence in community-dwelling older adults in China.

METHODS

A retrospective longitudinal study was conducted, and the data were obtained from a five-year national longitudinal cohort study of older adults in China between 2011 and 2015. The social determinants of health framework informed the data analysis and interpretation.

RESULTS

A total of 3893 older adults met the selection criteria and were included in the study. Three intrinsic capacity trajectories were identified: high trajectory (15.7 %), stable trajectory (52.7 %) and declining trajectory (31.6 %). Social determinants contribute to intrinsic capacity decline in older adults. Decreased cognitive function, psychological status, and locomotion at baseline were associated with care dependence.

CONCLUSION

Approximately thirty percent of the older adults in this cohort study experienced a decline in intrinsic capacity within a 5-year period. Social determinants contributed to this decline in older adults.

Intrinsic Capacity and Its Biological Basis: A Scoping Review

BACKGROUND

In 2015, the World Health Organization (WHO) introduced the concept of intrinsic capacity (IC) to define healthy aging based on functional capacity. In this scoping review, we summarized available evidence on the development and validation of IC index scores, the association of IC with health-related factors, and its biological basis. The review specifically focused on identifying current research gaps, proposed strategies to leverage biobank datasets, and opportunities to study the genetic mechanisms and gene-environment interactions underlying IC.

METHODS

The literature search was conducted across six databases, including PubMed, CINAHL, Web of Science, Scopus, AgeLine, and PsycINFO, using keywords related to IC.

RESULTS

This review included 84 articles, and most of them (n=38) adopted the 5-domains approach to operationalize IC, utilizing correlated five factors or bifactor structures. Intrinsic capacity has consistently shown significant associations with socio-demographic and health-related outcomes, including age, sex, wealth index, nutrition, exercise, smoking, alcohol use, ADL, IADL, frailty, multimorbidity, and mortality. While studies on the biological basis of the composite IC are limited, with only one study finding a significant association with the ApoE gene variants, studies on specific IC domains - locomotor, vitality, cognitive, psychological, and sensory suggest a heritability of 20-85% of IC and several genetic variants associated with these subdomains have been identified. However, evidence on how genetic and environmental factors influence IC is still lacking, with no available study to date.

CONCLUSION

Our review found that there was inconsistency in the use of standardized IC measurement tools and indicators, but the IC indices had shown good construct and predictive validity. Research into the genetic and gene-to-environment interactions underlying IC is still lacking, which calls for the use of resources from large biobank datasets in the future.