Intrinsic Capacity of Indian Older Adults: Metrics, Covariates, and Health Outcomes from a Nationwide Population-Based Epidemiological Study

Background and Objective: Healthy ageing is a person-centered approach, defined as “the process of developing and maintaining the functional ability that enables wellbeing in older age.” Functional ability includes an individual’s intrinsic capacity (mind and body), environmental factors influencing an individual, and the interaction between intrinsic capacity and environments. In this study, we applied the concept of IC within a nationally representative study of older adults in India, to develop an operational approach to confirm its main components, measure and examine factors associated with it. Methods: Data from the baseline survey of the Longitudinal Ageing Study in India, 2017–2018 were used to study the concept of IC among older adults in India, the metrics of physical and mental capacities and their determinants, and other health and wellbeing outcomes associated with IC. A national sample of 65,562 adults aged 45 years and older, representative of India and of its 35 states and union territories (except Sikkim), including spouses, participated in the study. We assessed the IC of adults aged 45 years and older and scored its five domains of vitality, locomotor, cognition, psychologic and sensory capacities through performance tests or biomarkers, and an overall score. We further examined the concurrent validity of IC with self-reported limitations in activities of daily living and instrumental activities of daily living, self-reported health, and life satisfaction.Results: Our analysis documents a robust pattern of IC scores among older adults in India. On average, IC scores of older adults varied substantially by state, with median values ranging from 67.3 in Telangana to 77.1 in Chandigarh. Generally, lower overall IC and in each domain were associated with increasing age, being a female (β=-11.6; 95% CI: -11.8, -11.4), living in rural areas, lower than primary education, lowest quintile of household monthly per capita consumption, undernutrition (β=-3.06; 95% CI: -3.26, -2.85), and one or more chronic diseases (β=-4.06; 95% CI: -4.41, -3.71). Physical activity and the practice of yoga (β=2.76; 95% CI: 2.49, 3.03) were associated with higher IC scores. Older adults with lower IC scores had more limitations on activities of daily living and instrumental activities of daily living, poorer self-reported health, and lower life satisfaction compared with those with higher scores. These associations remained strong after full adjustment of covariates.Interpretation: Analysis of this large cross-sectional dataset covering a heterogeneous population established the validity of IC measures in five domains with strong cross-state patterning. Our analysis demonstrates that IC, as a concept and as a metric, offers a unifying framework that reflects both the mind and body of older persons unlike existing measures that focus on different aspects of clinical care or disease management. Findings of a consistent adverse association of low IC with health and wellbeing measures call for comprehensive strategies to prevent and mitigate losses in intrinsic capacities across the life course.Funding: The research reported in this paper was based on the Longitudinal Ageing Study in India (LASI), wave 1, 2017–2018. LASI was funded by the Ministry of Health and Family Welfare, Government of India, the National Institute of Ageing, USA, and the United Nations Population Fund, India.Declaration of Interests: The authors declare no competing interests.Ethics Approval Statement: Ethical approval was granted by all collaborating institutions and the Indian Council for Medical Research. Separate informed consent was administered for household, individual, and biomarker components of the survey.