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

Zhao Y., Jiang Y., Tang P., Wang X., Guo Y., Tang L.

Abstract Background Intrinsic capacity refers to a broad range of health traits, including the physiological and psychological changes brought on by aging. Previous research has shown that intrinsic capacity, as an independent emerging construct, is a highly effective predictor of several health outcomes. Objective We aimed to summarise the predictive effect of intrinsic capacity at baseline on health outcomes among middle-aged and older adults. Design A systematic review and meta-analysis. Participants Middle-aged and older adults. Methods We systematically searched up to 3 April 2024 in 10 electronic databases. Studies investigating the predictive effect of baseline composite intrinsic capacity and health outcomes were included. Publications that had reported hazard ratios (HRs) or odd ratios (ORs) and 95% confidence intervals (CIs) as effect size were considered. Results A total of 23 publications were included. The sample size ranged from 100 to 17 031. The results of the meta-analysis showed statistically significant prediction of adverse health outcomes such as disability (OR = 1.84, 95% CI: 1.68–2.03, I2 = 41%, Pheterogeneity=.10), falls (OR = 1.38, 95% CI: 1.19–1.60, I2 = 45%, Pheterogeneity=.11), hospitalisation (OR = 2.25, 95% CI: 1.17–4.3, I2 = 68%, Pheterogeneity=.08), mortality (OR = 1.72, 95% CI: 1.54–1.91, I2 = 32%, Pheterogeneity=.12) and frailty (OR = 1.57, 95% CI: 1.45–1.70, I2 = 2%, Pheterogeneity=.31) by the baseline composite intrinsic capacity. Conclusions Declined intrinsic capacity has potential predictive value for adverse health outcomes, further high-quality study is needed to validate these findings and strengthen their cumulative impact. Attention to health outcomes should also focus on both breadth and category precision.

Beyene M.B., Visvanathan R., Ahmed M., Benyamin B., Beard J.R., Amare A.T.

AbstractBackground In 2015, the World Health Organization introduced the concept of intrinsic capacity (IC) to define the individual-level characteristics that enable an older person to be and do the things they value. This study developed an intrinsic capacity score for UK Biobank study participants and validated its use as a tool for health outcome prediction, understanding healthy aging trajectories, and genetic research. Methods Our analysis included data from 45,208 UK biobank participants who had a complete record of the ten variables included in the analysis. Factor adequacy was tested using Kaiser–Meyer–Olkin, Barthelt's, and the determinant of matrix tests, and the number of factors was determined by the parallel analysis method. Exploratory and confirmatory factor analyses were employed to determine the structure and dimensionality of indicators. Finally, the intrinsic capacity score was generated, and its construct and predictive validities as well as reliability were assessed. Results The factor analysis identified a multidimensional construct comprising one general factor (intrinsic capacity) and five specific factors (locomotor, vitality, cognitive, psychological, and sensory). The bifactor structure showed a better fit (comparative fit index = 0.995, Tucker Lewis index = 0.976, root mean square error of approximation = 0.025, root mean square residual = 0.009) than the conventional five-factor structure. The intrinsic capacity score generated using the bifactor confirmatory factor analysis has good construct validity, as demonstrated by an inverse association with age (lower intrinsic capacity in older age; beta = −0.035 (95%CI: −0.036, −0.034)), frailty (lower intrinsic capacity score in prefrail participants, beta = −0.104 (95%CI: (−0.114, −0.094)) and frail participants, beta = −0.227 (95%CI: −0.267, −0.186) than robust participants), and Charlson's comorbidity index for incident cases (a lower intrinsic capacity score associated with increased Charlson's comorbidity index, beta, =−0.019 (95%CI: −0.022, −0.015)). The intrinsic capacity score also predicted incident Charlson's comorbidity index (a one-unit increase in baseline intrinsic capacity score led to a lower Charlson's comorbidity index, beta = 0.147 (95%CI: −0.173, −0.121)) and mortality (a one-unit increase in baseline intrinsic capacity score led to 25 % lower risk of death, odds ratio = 0.75(95%CI: 0.663, 0.848)). Conclusion The bifactor structure showed a better fit in all goodness of fit tests. The intrinsic capacity construct has strong structural, construct, and predictive validities and is a promising tool for monitoring aging trajectories.

Tan F., Wei X., Zhang J., Zhao Y., Tong X., Michel J., Shao R., Gong E.

Abstract Background Assessing and monitoring intrinsic capacity (IC) is an effective strategy to promote healthy ageing by intervening early in high-risk populations. This review systematically analyzed the global detection rates of IC deficits and explored variations across diverse populations and data collection methods. Methods This study was preregistered with PROSPERO, CRD42023477315. In this systematic review and meta-analysis, we systematically searched ten databases from January 2015 to October 2023, for peer-reviewed, observational studies or baseline survey of trials that assessed IC deficits among older adults aged 50 and above globally following the condition, context and population approach. The main outcome was intrinsic capacity deficits which could be assessed by any tools. Meta-analyses were performed by a random-effect model to pool the detection rates across studies and subgroup analyses were conducted by populations and data collection methods. Results Fifty-six studies conducted in 13 countries were included in the review and 44 studies with detection rates of IC were included in the meta-analysis. The pooled detection rate of IC deficits was 72.0% (65.2%-78.8%) and deficits were most detected in sensory (49.3%), followed by locomotion (40.0%), cognition (33.1%), psychology (21.9%), and vitality (20.1%). Variations in detection rates of IC deficits were observed across studies, with higher rates observed in low- and middle-income countries (74.0%) and hyper-aged societies (85.0%). Study population and measurement tools also explained the high heterogeneity across studies. Conclusion IC deficits are common among older adults, while heterogeneity exists across populations and by measurement. Early monitoring with standardized tools and early intervention on specific subdomains of IC deficits are greatly needed for effective strategies to promote healthy ageing.

Salinas-Rodríguez A., Fernández-Niño J.A., Rivera-Almaraz A., Manrique-Espinoza B.

Abstract Background Life-long health inequalities exert enduring impacts and are governed by social determinants crucial for achieving healthy aging. A fundamental aspect of healthy aging, intrinsic capacity, is the primary focus of this study. Our objective is to evaluate the social inequalities connected with the trajectories of intrinsic capacity, shedding light on the impacts of socioeconomic position, gender, and ethnicity. Methods Our dynamic cohort study was rooted in three waves (2009, 2014, 2017) of the World Health Organization’s Study on Global AGEing and Adult Health in Mexico. We incorporated a nationally representative sample comprising 2722 older Mexican adults aged 50 years and over. Baseline measurements of socioeconomic position, gender, and ethnicity acted as the exposure variables. We evaluated intrinsic capacity across five domains: cognition, psychological, sensory, vitality, and locomotion. The Relative Index of Inequality and Slope Index of Inequality were used to quantify socioeconomic disparities. Results We discerned three distinct intrinsic capacity trajectories: steep decline, moderate decline, and slight increase. Significant disparities based on wealth, educational level, gender, and ethnicity were observed. Older adults with higher wealth and education typically exhibited a trajectory of moderate decrease or slight increase in intrinsic capacity. In stark contrast, women and indigenous individuals were more likely to experience a steeply declining trajectory. Conclusions These findings underscore the pressing need to address social determinants, minimize gender and ethnic discrimination to ensure equal access to resources and opportunities across the lifespan. It is imperative for policies and interventions to prioritize these social determinants in order to promote healthy aging and alleviate health disparities. This approach will ensure that specific demographic groups receive customized support to sustain their intrinsic capacity during their elder years.

Huang Z., Lai E.T., Luo Y., Woo J.

The World Health Organization defined healthy ageing as the maintenance of functional ability with ageing. Intrinsic capacity is a measurement of healthy ageing, and can be shaped by social determinants. However, an overall understanding of how multiple social determinants contribute to intrinsic capacity remains unclear. We aim to summarize observational studies investigating the relationships between social determinants and intrinsic capacity among community-dwelling adults.A systematic search was conducted through Medline, Embase, PsycInfo, Web of Science, and CINAHL until August 14, 2023.After reviewing 813 articles, we included 21 studies from nine countries in Asia, Europe, and America. Seventeen studies used a cross-sectional design and the others were longitudinal studies. Social determinants related to intrinsic capacity can be classified into five domains, containing socioeconomic status (16, 76.2% of studies), lifestyles (14, 66.7%), psychosocial factors (9, 42.9%), material circumstances (4, 19.0%), and healthcare systems (1, 4.8%). Strong evidence supported that better intrinsic capacity was associated with higher education, higher wealth, more physical activities, no smoking, more social engagement, and being married or partnered. The relationships of intrinsic capacity with dietary patterns and alcohol drinking were contradictory across studies. Research on the associations of working status, housing environments, and healthcare accessibility with intrinsic capacity was insufficient to draw conclusions.These findings highlight roles of socioeconomic status, lifestyles, and psychosocial factors in improving intrinsic capacity thus promoting healthy ageing. Future research is needed to investigate causal relationships between social determinants and intrinsic capacity, especially material circumstances and healthcare systems.

Zhao Y., Chen Y., Xiao L.D., Liu Q., Nan J., Li X., Feng H.

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. 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. 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. 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.

Wei X., Chen Y., Qin J., Yang Y., Yang T., Yan F., Zhang Z., Han L., Ma Y.

AbstractIntroductionIn 2015, the term ‘intrinsic capacity’ (IC) was proposed by the World Health Organisation to promote healthy aging. However, the factors associated with IC are still discrepant and uncertain.AimWe aim to synthesise the factors connected with IC.MethodsThis scoping review followed the five‐stage framework of Arksey and O'Malley and was reported using PRISMA‐ScR guidelines.ResultsIn all, 29 articles were included. IC of older adults is associated with demographic characteristics, socioeconomic factors, disease conditions, behavioural factors, and biomarkers. Age, sex, marital status, occupation status, education, income/wealth, chronic diseases, hypertension, diabetes, disability, smoking status, alcohol consumption, and physical activity were emerged as important factors related to the IC of older adults.ConclusionsThis review shows that IC is related to multiple factors. Understanding these factors can provide the healthcare personnel with the theoretical basis for intervening and managing IC in older adults.Relevance to Clinical PracticeThe influencing factors identified in the review help to guide older adults to maintain their own intrinsic capacity, thereby promoting their health and well‐being. The modifiable factors also provide evidence for healthcare personnel to develop targeted intervention strategies to delay IC decline.No Patient or Public ContributionAs this is a scoping review, no patient or public contributions are required.

Lu W., Guyonnet S., Martinez L.O., Lucas A., Parini A., Vellas B., de Souto Barreto P.

Intrinsic capacity (IC), the composite of physical and mental capacities, declines with age at different rates and patterns between individuals. We aimed to investigate the association between longitudinal IC trajectories and plasma biomarkers of two hallmarks of aging—chronic inflammation and mitochondrial dysfunction—in older adults. From the Multidomain Alzheimer Preventive Trial (MAPT), we included 1271 community-dwelling older people (mean [SD] age = 76.0 [4.3] years) with IC data over four years. Group-based multi-trajectory modeling was performed to identify clusters of the participants with similar longitudinal patterns across four IC domains: cognition, locomotion, psychology, and vitality. Five IC multi-trajectory groups were determined: low in all domains (8.4%), low locomotion (24.6%), low psychological domain (16.7%), robust (i.e., high in all domains except vitality; 28.3%), and robust with high vitality (22.0%). Compared to the best trajectory group (i.e., robust with high vitality), elevated levels of plasma interleukin-6 (IL-6), tumor necrosis factor receptor-1 (TNFR-1), and growth differentiation factor-15 (GDF-15) were associated with a higher risk of belonging to the “low in all domains” group (IL-6: relative risk ratio (RRR) [95% CI] = 1.42 [1.07 – 1.88]; TNFR-1: RRR = 1.46 [1.09 – 1.96]; GDF-15: RRR = 1.99 [1.45 – 2.73]). Higher IL-6 and GDF-15 also increased the risk of being in the “low locomotion” group. GDF-15 outperformed other biomarkers by showing the strongest associations with IC trajectory groups. Our findings found that plasma biomarkers reflecting inflammation and mitochondrial impairment distinguished older people with multi-impaired IC trajectories from those with high-stable IC.

Zhang N., Zhang H., Sun M., Zhu Y., Shi G., Wang Z., Wang J., Wang X.

Knowledge of how intrinsic capacity (IC) shape functional ability (FA) trajectories in later life remains unclear. We investigated the changes in IC and their impact on 5-years FA trajectories in the Chinese older population. A total of 1640 older adults from the Rugao Longitudinal Ageing Study were included and analyzed. FA was assessed by The Lawton Instrumental Activities of Daily Living Scale (IADLs). We used cognition, psychology, locomotion, sensory capacity, and vitality to capture the multiple domains of IC according to the ICOPE method. The IC was derived retrospectively from variables collected before this was described by WHO. At baseline, a higher IC was associated with higher IADLs (β = 0.98, 95% CI 0.90, 1.06, P < 0.001). Individuals with declines in IC between wave1 and wave2 experienced a faster decline in IADLs over time (β = − 0.28, 95% CI − 0.40, − 0.16, P < 0.001) after considering covariates. One or more impairment IC scores at baseline strongly predicted death (HR = 1.20, 95% CI 1.11, 1.30, P < 0.001). In addition, according to the IC scores at baseline, we stratify IC in low, middle, and high, compared with those in the high IC score, those in the low were associated with a 2.56-fold (95% CI 1.64, 4.01, P < 0.001) higher risk of mortality, after adjustment for variables. Changes in IC shape FA trajectories. IC impairment is associated with an increased risk of death. Assessing intrinsic capacity would facilitate early identification of older adults at high risk of adverse outcomes and prompt targeted interventions.

Sano J., Hirazawa Y., Komamura K., Okamoto S.

AbstractAs longevity occurs, people encounter various risks associated with ageing, including economic uncertainty and health issues. Therefore, in addition to extending healthy life expectancy, it is crucial to create an environment where older people can live better even when their intrinsic capacity declines. Additionally, integrated and comprehensive care for older adults is needed to maintain their functional ability and well-being at higher levels. This review provides an overview of the systems and initiatives in Japan, a forerunner of population ageing that supports the quality of life of older people and summarises their remaining challenges. In Japan, with support for access to necessary care available from social welfare councils and community comprehensive support centres, various health and welfare services are provided to respond to the needs of people with different levels of intrinsic capacity, including medical care, preventive care, long-term care, adult guardianship systems, pensions, and social assistance. Nevertheless, there are challenges for the systems, including the gap between life and healthy life expectancy, moderate accumulation and decumulation of retirement assets, lack of human and financial resources for care, and user-unfriendliness and non-covered needs of the current system. Therefore, integrated and comprehensive care beyond health and long-term care is needed to maintain the well-being of older adults, even with their intrinsic capacity declining.

Yu J., Jin Y., Si H., Bian Y., Liu Q., Qiao X., Ji L., Wang W., Wang C.

Background The ecological model of health and ageing has proposed that functional ability (FA) is determined by the interaction between intrinsic capacity (IC) and environmental characteristics. This study empirically examined how social support, as an important social environmental resource, interacts with IC to affect FA trajectories among older adults. Methods This was a prospective three-wave cohort study with a sample of 775 community-dwelling older adults. Social support, IC and FA were assessed using the Social Support Rating Scale, the revised Integrated Care for Older People screening tool and the Lawton Instrumental Activities of Daily Living Scale, respectively. Latent growth curve models (LGCM) were implemented to test their relationships. Results FA significantly declined over 3 years, and the detrimental effect of impaired IC on the deterioration rate of FA was buffered by subjective support but was aggravated by support utilization and was not changed by objective support. FA decline among older adults with impaired IC was observed in those with low subjective support or with high support utilization but not in those with high subjective support or with low support utilization. Among older adults with intact IC, FA decline was observed in those with low support utilization but not in those with high support utilization or with low or high subjective support. Conclusions Subjective support may prevent FA decline among older adults with impaired IC, while support utilization may benefit older adults with intact IC but may be detrimental for those with impaired IC. Social support interventions to optimize FA trajectories should improve older adults' perceptions of support and bridge the gap in support utilization among older adults with impaired IC.

Liang Y., Shang S., Gao Y., Zhai J., Cheng X., Yang C., Zhang R.

AbstractObjectives This review summarizes the measurements of intrinsic capacity in 5 domains across different studies and evaluates the quality of research papers. Design Scoping review of papers written in English and Chinese published in peer-reviewed journals. Setting and Participants The intrinsic capacity of older adults was assessed using the multidomain structure (Cognition, Locomotion, Psychological, Sensory and Vitality) proposed by the World Health Organization. Methods We searched PubMed, MEDLINE, and Web of Science for papers in English, and CNKI, CBM for papers written in Chinese published until September 13, 2022. Both cross-sectional and cohort studies of multidomain measurements of intrinsic capacity were included. Three independent reviewers appraised the quality of studies, and Cohen's kappa was calculated to determine interrater reliability. Data were listed by author, year, setting, country, age range and number of participants, measurement and calculation of intrinsic capacity, and data acquisition method. Results We included 53 studies. Twenty-one studies were of high quality, 31 studies were of moderate quality, and 1 study was of low quality. Measurements of intrinsic capacity and derivation of the summative index score were heterogeneous. Intrinsic capacity was usually assessed in 4 or 5 domains. Sensory was the most frequently overlooked domain or subdivided into vision and hearing in some studies. Indicators of vitality were the most heterogeneous. We also found consistency in heterogeneous measurements. The most common measurements of cognition, locomotion, and psychological capacity were the Mini-Mental State Examination, Short Physical Performance Battery, and Geriatric Depression Scale respectively. Self-reported questionnaires were commonly adopted in sensory domain. The Mini-Nutritional Assessment and grip strength were the most measured indicators of vitality. Conclusions and Implications The focus on capacity and disease should be balanced to better promote healthy aging in older adults. Heterogeneity of intrinsic capacity measurements underscores the need for consensus about standardized measurements and calculation procedures.

Yu R., Lai D., Leung G., Woo J.

Intrinsic capacity (IC) declines progressively with age, thereby increasing the risk of disability. However, it is less known whether IC trajectories are associated with disability. This study aims to identify the different patterns of IC trajectories in older people, and examine their determinants and associations with Instrumental Activities of Daily Living (IADL). Cohort study. Community centres in different regions in Hong Kong. Longitudinal data from community-dwelling older people aged 60 years or above (n = 1371) collected between 2016 and 2021 was analysed. Their mean age was 74.5 years, and 78.7% of them were female. Repeated measurements of a set of 14 self-reported items were used to generate IC scores at four time points using a bi-factor model. Latent class growth analysis was performed to identify classes with distinct IC trajectories. The association between class membership and IADL disability was then examined using logistic regression. Three distinct IC trajectories were identified. The 1st class included those with the highest level of baseline IC and the least declining trajectory, whereas the 3rd class was composed by those with the lowest level of baseline IC and the most declining trajectory. Older age, female gender, lower perceived financial adequacy, living in public or subsidized housing, and chronic diseases were associated with the 3rd class. After adjusting for demographic factors, socioeconomic status, and the number of chronic diseases, the 1st class was more likely to preserve IADL when compared against the 2nd class, with OR being 3.179 (95% CI: 2.152–4.793), whereas for the 3rd class, the OR was 0.253 (95% CI: 0.178–0.359). Monitoring IC trajectories is of relevance to clinical practice, as it helps shift the focus from treating acute episodes of illness to preserving the functional ability of older people.

Campbell C.L., Cadar D., McMunn A., Zaninotto P.

Abstract Background Intrinsic capacity (IC) is a new concept in the healthy ageing field and has many operationalised definitions. In this study, we operationalised IC using item response theory in the English Longitudinal Study of Ageing (ELSA) and tested the predictive value of the scale using subsequent functional ability, mortality, and hospital admission. Methods IC was measured at baseline (2004, Wave 2) using 14 dichotomous indicators: word recall, orientation in time, balance, chair rises, walking speed, upper mobility, lower mobility, eyesight, hearing, grip strength, BMI, waist circumference, depressive symptoms, life satisfaction. A two-parameter item response theory model was used to generate a scale of IC at baseline. Logistic regression was used for the prediction of subsequent difficulties, measured by difficulties with ≥1 activities of daily living (ADLs) and ≥1 instrumental activities of daily living (IADLs) at 4 and 8 years after baseline. Competing risk and cox regressions were employed to test prediction of hospital admission and mortality, respectively, over a 14-year follow-up. Results Intrinsic capacity scores were generated for 4,545 individuals aged on average 70.8 years (SD 7.93). Better baseline IC scores were associated with reduced risk of subsequent difficulties with ADLs and IADLs, hospital admission (SHR=0.99, 95%CI 0.98-0.99) and mortality (HR=0.98, 95%CI 0.98–0.99), when adjusted for sociodemographic and health-related covariates. Conclusions These results suggest the utility of this IC score as a measure of risk for future adverse outcomes in older people, potentially above that indicated by other sociodemographic and health-related factors.

Pot A.M., Oliveira D., Hoffman J.

As we embark on the UN Decade of Healthy Ageing (2021–30),1 countries and regions around the globe have started to establish their plans to promote healthy ageing across the life span, enabling people to not only live longer, but to also have healthier lives.2,3 The Path to Healthy Ageing in China: A Peking University–Lancet Commission4 is an example of such an initiative. We consider this Commission's report to be an important step towards improving the lives of millions of older people. The report places a strong emphasis on the economic burden of ageing, health service development, and the health management and control of chronic conditions.