Intrinsic Capacity: Validation of a New WHO Concept for Healthy Aging in a Longitudinal Chinese Study

Abstract

Background The World Health Organization has proposed a model of healthy aging built around the concept of functional ability, comprising an individual’s intrinsic capacity, the physical and social environment they occupy, and interactions between the two. However, these constructs have been poorly defined. We examined the structure of intrinsic capacity in a representative sample of the Chinese population aged 60 years and over and assessed its value in predicting declining performance in instrumental activities of daily living (IADLs) and activities of daily living (ADLs) using similar methods to a construct validation previously undertaken in an English cohort. Methods De-identified data were accessed on 7643 participants of the China Health and Retirement Longitudinal Study (CHARLS) 2011 and 2013 waves. Incrementally related structural equation modelling was applied, including exploratory and confirmatory factor analysis, and path analysis. Multiple linear regression tested construct validity, and simple and serial mediation models assessed predictive validity. Results Factor loadings for the models showed a clear structure for intrinsic capacity: one general factor with five subfactors - locomotor, cognitive, psychological and sensory capacities, and vitality (reflecting underlying physiologic changes). Intrinsic capacity predicted declining performance in both IADLs (Standardized Coefficient (SE) -0.324 (0.02), p<0.001) and ADLs (-0.227 (0.03), p<0.001), after accounting for age, sex, education, wealth and number of chronic diseases. Each characteristic was associated with intrinsic capacity, providing strong construct validity. Conclusions Assessment of intrinsic capacity provides valuable information on an individual’s subsequent functioning beyond that afforded by age, other personal factors and multimorbidity.

Development and Validation of a Multidimensional Population-Based Healthy Aging Scale: Results From the China Health and Retirement Longitudinal Study

“…Taken together, we conclude that both the general HAS and the subdomain factors need to be reported. Although different indicators were included to develop the HAS, our findings are consistent with previous studies that concluded healthy aging is a multidimensional concept (10,20).…”

“…According to the WHO's model, healthy aging is a multidimensional concept that includes both intrinsic capacity and functional ability ( 5 ), which was also confirmed by a previous study ( 10 ). Previous studies have demonstrated that intrinsic capacity is multidimensional, including psychological, sensory, cognitive, vitality, and locomotor components ( 11 , 20 ). In this study, we used data from a large national longitudinal study to firstly conceptualize healthy aging as a general factor and five subdomain factors, as identified by the EFA.…”

Intrinsic Capacity in Older Adults: Recent Advances

“…Similarly, Beard [ 8 ] assessed walking speed, chair-stand test, balance, grip strength, forced expiratory volume, blood assay, sensory, cognitive function, and sleep in the English Longitudinal Study on Ageing (ELSA) and found that five subfactors (psychological, sensory, cognitive, vitality, and locomotor) formed a structure to better predict future functioning, which is consistent with the findings of Cesari. A recent Chinese study also validated this structure using the same method as in ELSA [ 9 ]. Based on these studies, researchers from different countries have evaluated and verified the predictive value of the decline of IC and its domains in older adults.…”

“How are You Doing?” on the Healthy Aging of the Community-Dwelling Oldest-Old in the Shadow of the COVID-19 Pandemic

“…While life span and course can be influenced by multiple factors, not all of which can be controlled, the health of older people can be enhanced when they have full access to healthcare and services. Moreover, recent studies have shown that healthy aging is largely determined by the ability to maintain both physical and mental capacity, together known as intrinsic capacity ( Beard et al, 2021 ). With a rapidly growing aging population, all societies need to plan and invest adequately and in a timely manner in healthcare services and activity facilities for older people to extend their healthy years and strengthen their intrinsic capacities.…”

“…To date, only a few quantitative studies have been conducted to promote healthy aging ( Leung et al, 2020 ), validate the concept of intrinsic capacity ( Beard et al, 2021 ), or analyze factors related to healthy aging based on open databases ( Feng et al, 2019 ). Still unknown is how older people, especially the oldest-old, feel about their surrounding environment, and what their experience of healthy aging is, not only physically but also holistically.…”