Intrinsic capacity: an under-researched concept in geriatrics

Umbrella review of nonpharmacological interventions for intrinsic capacity in older adults

PURPOSE

This study aims to synthesize existing evidence on the effectiveness of nonpharmacological interventions designed to increase the intrinsic capacity (IC) of community-dwelling older adults.

METHODS

An umbrella review of systematic reviews from 2015 to October 31, 2024, with no language restrictions, was conducted. The review included five databases, including Embase, Ovid MEDLINE, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), the Cochrane Central Register of Controlled Trials (CENTRAL), and the Joanna Briggs Institute (JBI) Library. Studies followed the preferred reporting items for overviews of reviews (PRIOR) statement. Eligible studies were systematic review and meta-analysis (SRMAs) that included any type of research aimed at enhancing IC in community-dwelling older adults (aged ≥60 years). The interventions covered seven domains: locomotion, vitality, cognitive function, psychological health, sensory function, sleep, and continence. Risk of bias and study quality were extracted via the AMSTAR tool, and GRADE approach was applied to assess the certainty of evidence.

FINDINGS

Out of 6407 initially identified articles, 29 SRMAs comprising 400 studies with a total sample size of 43,849 participants were included. Mobility-focused interventions were the most studied among the seven domains of IC. Moderate to low-quality evidence supports the effectiveness of intrinsic foot muscle strengthening and gait/muscle training for improving locomotor functions in older adults with frailty or acute functional decline. Nonpharmacological interventions targeting cognitive and psychological functions ranked second in the volume of available evidence. No effective sensory or continence interventions were identified. Overall, interventions have demonstrated varying effectiveness, with impacts ranging from moderate to very low across the domains of IC.

INTERPRETATIONS

This umbrella review provides a comprehensive assessment of nonpharmacological interventions for enhancing IC in older adults, highlighting the effectiveness of mobility/muscle strength training for improving locomotor function among frail older adult or those experiencing functional decline. However, the evidence for interventions targeting other IC domains remains limited, particularly for sensory function, and continence management. Future research should prioritize high-quality trials evaluating interventions in these areas to develop evidence-based guidelines for improving overall IC and promoting healthy aging in older adults.

The Longitudinal Aging Study Amsterdam: design and cohort update 2025

The Longitudinal Aging Study Amsterdam (LASA) is an ongoing prospective cohort study of older adults in the Netherlands, with data on multiple domains of functioning available over a period of more than 30 years of follow-up. The study started in 1992 with a nationally representative sample of older adults aged 55-84 years. Over the years, three refresher cohorts (two cohorts aged 55-64 years in 2002 and in 2012, and one cohort aged 60-86 years in 2024) were added. The main aim of LASA was to describe determinants, trajectories and consequences of (changes in) physical, cognitive, emotional and social functioning. LASA has multiple strengths, including its multidisciplinary character, the very long period of follow-up, and the cohort-sequential design which enables the study of longitudinal changes as well as historical time trends in functioning. So far, findings based on data from LASA have been reported in more than 800 scientific publications (see www.lasa-vu.nl ). In this article, we provide an update of the design and methods of LASA, including a description of several ancillary studies such as the Loneliness study and the COVID-19 study.

Intrinsic Capacity Trajectories: Implications for Subsequent Falls and Hospitalizations Among Older Adults

BACKGROUND

Intrinsic capacity (IC) is the composite of an individual's physical and mental capacities. However, the association between IC trajectories and falls and hospitalizations remains uncertain. This study aimed to determine the IC trajectories among older adults, investigating its association with subsequent risk of falls and hospitalizations.

METHODS

This study enrolled 3 902 older adults aged ≥65 from the National Health and Aging Trends Study (Wave 2015-2019). A bifactor model was used for repeated measurements of the 5 IC domains to generate IC scores for 4 time points (Wave 2015-2018). IC trajectories were identified using group-based trajectory modeling, and modified Poisson regression was used to analyze the associations between IC trajectories and subsequent fall and hospitalization risk.

RESULTS

The mean age of the participants was 76.70 years (standard deviation = 6.78), and the majority were female (57.3%). Three IC trajectories were identified, including persistently low (17.86%), persistently moderate (33.96%), and persistently high (48.18%). Compared with the persistently low class, the moderate and high classes have significantly lower fall and hospitalization risks. Multivariate-adjusted rate ratios fall occurrence were 0.87 (95% confidence interval [CI]: 0.78-0.98) and 0.74 (95% CI: 0.65-0.85), for multiple falls were 0.81 (95% CI: 0.68-0.96) and 0.52 (95% CI: 0.41-0.66), for hospitalization occurrence were 0.76 (95% CI: 0.66-0.87) and 0.48 (95% CI: 0.39-0.58), and for multiple hospitalizations were 0.65 (95% CI: 0.53-0.80) and 0.37 (95% CI: 0.28-0.48), respectively.

CONCLUSIONS

IC trajectories were associated with falls and hospitalizations. Strategies focusing on improving and maintaining IC at a higher level over time could help reduce the subsequent risk of falls and hospitalizations.

Understanding Individual Differences in Happiness Sources and Implications for Health Technology Design: Exploratory Analysis of an Open Dataset

BACKGROUND

Psychologists have developed frameworks to understand many constructs, which have subsequently informed the design of digital mental health interventions (DMHIs) aimed at improving mental health outcomes. The science of happiness is one such domain that holds significant applied importance due to its links to well-being and evidence that happiness can be cultivated through interventions. However, as with many constructs, the unique ways in which individuals experience happiness present major challenges for designing personalized DMHIs.

OBJECTIVE

This paper aims to (1) present an analysis of how sex may interact with age, marital status, and parental status to predict individual differences in sources of happiness, and (2) to present a preliminary discussion of how open datasets may contribute to the process of designing health-related technology innovations.

METHODS

The HappyDB is an open database of 100,535 statements of what people consider to have made them happy, with some people asking to consider the past 24 hours (49,831 statements) and some considering the last 3 months (50,704 statements). Demographic information is also provided. Binary logistic regression analyses are used to determine whether various groups differed in their likelihood of selecting or not selecting a category as a source of their happiness.

RESULTS

Sex and age interacted to influence what was selected as sources of happiness, with patterns being less consistent among female individuals in comparison with male individuals. For marital status, differences in sources of happiness were predominantly between married individuals and those who are divorced or separated, but these were the same for both sexes. Married, single, and widowed individuals were all largely similar in their likelihood of selecting each of the categories as a source of their happiness. However, there were some anomalies, and sex appeared to be important in these anomalies. Sex and parental status also interacted to influence what was selected as sources of happiness.

CONCLUSIONS

Sex interacts with age, marital status, and parental status in the likelihood of reporting affection, bonding, leisure, achievement, or enjoying the moment as sources of happiness. The contribution of an open dataset to understanding individual differences in sources of happiness is discussed in terms of its potential role in addressing the challenges of designing DMHIs that are ethical, responsible, evidence based, acceptable, engaging, inclusive, and effective for users. The discussion considers how the content design of DMHIs in general may benefit from exploring new methods informed by diverse data sources. It is proposed that examining the extent to which insights from nondigital settings can inform requirements gathering for DMHIs is warranted.

Sensitivity and Specificity of Three Measures of Intrinsic Capacity in Older People Aged 80 and Over in Nursing Homes

Purpose

Intrinsic capacity (IC), a crucial indicator for the United Nations Decade of Healthy Ageing 2021-2030, is defined by WHO as the foundation of functional ability, representing the composite of all physical and mental capacities of an individual. IC spans five function domains: Locomotor, psychological, cognitive, vitality, and sensory (including vision and hearing). Accurate IC assessment is vital for effective interventions, yet comparative analyses of these tools are scarce. Consequently, we evaluated the diagnostic accuracy of three IC assessment tools in individuals aged 80 and above-Integrated care for older people (ICOPE) Step 1, ICOPE Step 2, and the Lopez-Ortiz's IC scoring system.

Patients and Methods

This cross-sectional analysis included a total of 475 participants aged ≥80 years between July 2023 and January 2024 in 11 nursing homes in Ningbo, Zhejiang Province, China. To assess that included sociodemographic and health-related information alongside the three IC tools. Diagnostic efficacy was gauged using sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), accuracy, Youden index, and the area under the curve (AUC).

Results

The detection of IC decline exceeded 85% across all methods. Using ICOPE Step 2 as a benchmark, ICOPE Step 1 showed robust performance across four domains of locomotion, psychological, cognitive, and vitality, whereas the Lopez-Ortiz's IC scoring system was generally ineffective.

Conclusion

All three IC assessment methods have limitations. To save resources, ICOPE Step 1 can be considered for direct assessment in non-sensory domains. Conversely, the ICOPE Step 2 and Lopez-Ortiz's IC scoring systems exhibited overly stringent and lenient thresholds, respectively. At this stage, IC assessment tools cannot balance subjectivity and objectivity; thus, it is recommended that the appropriate tool be selected according to actual application scenarios. Continuous improvement of IC assessment tools remains a requirement for future studies.

The development of intrinsic capacity measures for longitudinal research: The Longitudinal Aging Study Amsterdam

BACKGROUND

The World Health Organization has introduced the construct of intrinsic capacity (IC) as an important component of healthy ageing and overall well-being in older adults The present study aimed to develop domain-specific and composite IC scores and to validate these scores by examining their longitudinal relation with functioning.

METHODS

We used prospective data on participants aged 57 to over 90 years, with a 10-year follow-up, from the Longitudinal Aging Study Amsterdam, an ongoing cohort study of older Dutch men and women Using a formative, stepwise approach, we identified indicators across the different domains of IC, i.e. vitality, sensory, cognition, psychology, and locomotion, using a combination of unidimensional factor analyses and Partial Least Squares Structural Equation Modelling (PLS-SEM). Next, domain-specific and composite IC scores were generated, and the construct validity (score across age groups) and criterion validity (relationship with change in functional limitations) were assessed.

RESULTS

The multiple unidimensional factor analyses and PLS-SEM identified a total of 18 indicators, covering the five domains of IC. The mean composite IC score was 70.9 (SD = 0.9) in men and 69.7 (0.8) in women. The domain-specific and composite IC scores all showed good construct validity, with known-group validation results indicating age-related declines. A higher composite IC score was associated with less functional limitations over time (B = 0.20, 95%CI [0.19, 0.22]).

CONCLUSION

The developed domain-specific IC scores and the composite IC score effectively discriminated age-related declines in IC. Additionally, the composite IC score was longitudinally associated with functional limitations. By creating this comprehensive and reliable tool for tracking IC, we aim to provide valuable insights into the dynamics of ageing and support more effective strategies for promoting health and well-being throughout later life. These scores establish a foundation for future research to track longitudinal changes across various IC domains and relate these changes to key age-related outcomes.

Intrinsic capacity loss rates and protective factors among individuals aged 80 years and older in Chinese nursing homes: A latent class analysis

Prior to this cross-sectional study, the intrinsic capacity (IC) loss rates and protective factors in nursing homes for individuals aged 80 and older remained unexplored. Analysing 434 participants, this study found 86.9 % of individuals experienced the loss of at least one IC domain, with detailed losses in locomotion, vision, vitality, hearing, psychological, and cognitive capacities at rates of 83.2 %, 52.8 %, 50.9 %, 46.5 %, 44.9 %, and 44.0 %, respectively. Following latent class analysis (LCA), five distinct IC impairment patterns were noted, with locomotor impairment emerging as a central component across most classes. IC protective factors for persons aged 80 years and older included financial stability, being male or younger within the cohort, junior high school or higher education, being married, no smoking history, manageable comorbidity levels, minimal medication use, good sleep, and not using assistive devices. Based on these five classes, this study provides a potential practical framework alongside recommendations for IC care strategies in the oldest-old, emphasising the importance of locomotor function in maintaining the overall IC.

Intrinsic capacity and recent falls in adults 80 years and older living in the community: results from the ilSIRENTE Study

BACKGROUND

Falls in older adults significantly impact overall health and healthcare costs. Intrinsic capacity (IC) reflects functional reserve and is an indicator of healthy aging.

AIMS

To explore the association between IC and recent falls (≤ 90 days) in community-dwelling octogenarians from the Aging and Longevity in the Sirente geographic area (IlSIRENTE) study.

METHODS

The Minimum Data Set for Home Care (MDS-HC) and supplementary questionnaires and tests were used to assess the five IC domains: locomotion, cognition, vitality, psychology, and sensory. Scores in each domain were rescaled using the percent of maximum possible score method and averaged to obtain an overall IC score (range 0-100).

RESULTS

The study included 319 participants (mean age 85.5 ± 4.8 years, 67.1% women). Mean IC score was 80.5 ± 14.2. The optimal IC score cut-off for predicting the two-year risk of incident loss of at least one activity of daily living (ADL) was determined and validated in a subset of 240 individuals without ADL disability at baseline (mean age 84.7 ± 4.4 years, 67.1% women). Participants were then stratified into low (< 77.6) and high (≥ 77.6) IC categories. Those with high IC (63.9%) were younger, more often males, and had lower prevalence of recent falls, disability, multimorbidity, and polypharmacy. Logistic regression models including IC as a continuous variable revealed a significant association between higher IC and lower odds of falls. This association was significant in the unadjusted (odds ratio [OR] 0.96, 95% confidence interval [CI] 0.94-0.98, p < 0.001), age- and sex-adjusted (OR 0.96, 95% CI 0.94-0.98, p < 0.001), and fully adjusted models (OR 0.96, 95% CI 0.93-0.99, p = 0.003). When considering IC as a categorical variable, unadjusted logistic regression showed a strong association between high IC and lower odds of falls (OR 0.31, 95% CI 0.16-0.60, p < 0.001). This association remained significant in both the age- and sex-adjusted (OR 0.30, 95% CI 0.15-0.59, p < 0.001) and fully adjusted models (OR 0.33, 95% CI 0.16-0.82, p = 0.007). The locomotion domain was independently associated with falls in the unadjusted (OR 0.98, 95% CI 0.97-0.99, p < 0.001), age- and sex-adjusted (OR 0.97, 95% CI 0.96-0.99, p < 0.001), and fully adjusted model (OR 0.98, 95% CI 0.96-0.99, p < 0.001).

DISCUSSION

This is the first study using an MDS-HC-derived instrument to assess IC. Individuals with higher IC were less likely to report recent falls, with locomotion being an independently associated domain.

CONCLUSIONS

Lower IC is linked to increased odds of falls. Interventions to maintain and improve IC, especially the locomotion domain, may reduce fall risk in community-dwelling octogenarians.

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.