Intrinsic capacity and healthy aging in the United Kingdom and Brazil: a coordinated analysis of 2 population-based cohort studies.

Abstract

Background: Although intrinsic capacity (IC) is a multidimensional marker of healthy aging, cross-country validation in diverse cultural and socioeconomic contexts remains limited. We study aimed to harmonize the operationalization of IC and examine its associations with sociodemographic characteristics and health outcomes in the United Kingdom and Brazil.

Methods: Nationally representative cohorts of community-dwelling older adults in both countries, aged ≥60 years from the English Longitudinal Study of Ageing (n = 3392) and Brazilian Longitudinal Study of Ageing (n = 3580). IC was derived using bi-factor models comprising locomotor, cognition, psychological, sensory, and vitality measures, standardized to a 0-100 scale. Linear regressions assessed IC associations with sociodemographic factors. Logistic regressions examined IC associations with poor/fair self-rated health and disability in basic activities of daily living (ADL) and instrumental ADL (IADL). We tested whether education and wealth modified these associations.

Results: Mean IC scores were lower in women than in men, with differences of 3.06 points (95% confidence interval [CI] = 2.30-3.82) in the United Kingdom and 8.14 (95% CI = 7.40-8.90) in Brazil. Older age, non-White race/ethnicity, less education, and lower wealth were also linked to lower IC scores. Higher IC was associated with lower odds of poor/fair self-rated health in the United Kingdom (odds ratio [OR] = 0.32; 95% CI = 0.29-0.35) and Brazil (OR = 0.54; 95% CI = 0.48-0.61). Higher IC was also linked to lower odds of ADL and IADL disability in both cohorts. No significant interactions were found.

Conclusions: IC showed consistent associations with sociodemographic factors and health outcomes both countries. IC may inform equitable, person-cent red healthy aging policies for older adults in diverse contexts.