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

Mean IC scores were lower in women than in men in both countries, with a larger sex difference observed in Brazil than in the United Kingdom.

• Difference in IC scores between women and men was 3.06 points (95% CI = 2.30–3.82) in the United Kingdom.
• Difference in IC scores between women and men was 8.14 points (95% CI = 7.40–8.90) in Brazil.
• Samples included community-dwelling older adults aged ≥60 years: n = 3392 from ELSA (UK) and n = 3580 from ELSA-Brasil (Brazil).
• IC was derived using bi-factor models comprising locomotor, cognition, psychological, sensory, and vitality measures, standardized to a 0–100 scale.

Older age, non-White race/ethnicity, less education, and lower wealth were associated with lower IC scores in both countries.

• These associations were found consistently across both the UK and Brazilian cohorts.
• Linear regressions were used to assess IC associations with sociodemographic factors.
• The study used nationally representative cohorts of community-dwelling older adults from the English Longitudinal Study of Ageing and the Brazilian Longitudinal Study of Ageing.

Higher IC was associated with lower odds of poor or fair self-rated health in both countries, with a stronger association in the United Kingdom than in Brazil.

• In the United Kingdom, higher IC was associated with an odds ratio of 0.32 (95% CI = 0.29–0.35) for poor/fair self-rated health.
• In Brazil, higher IC was associated with an odds ratio of 0.54 (95% CI = 0.48–0.61) for poor/fair self-rated health.
• Logistic regressions were used to examine IC associations with health outcomes.
• Both associations indicate that higher IC corresponded to lower odds of poor/fair self-rated health.

Higher IC was associated with lower odds of disability in both basic activities of daily living (ADL) and instrumental ADL (IADL) in both countries.

• Associations between IC and ADL and IADL disability were found in both the UK and Brazilian cohorts.
• Logistic regressions were used to examine these associations.
• Disability outcomes examined included both basic ADL and instrumental ADL.

Education and wealth did not significantly modify the associations between IC and health outcomes in either country.

• No significant interactions were found between education or wealth and IC in relation to health outcomes.
• Interaction testing was conducted in both the UK and Brazilian cohorts.
• This finding held for both self-rated health and ADL/IADL disability outcomes.

IC was operationalized using a bi-factor model harmonized across both countries, comprising five domains: locomotor, cognition, psychological, sensory, and vitality.

• IC scores were standardized to a 0–100 scale to allow cross-country comparison.
• The bi-factor model was used to derive IC from measures within each of the five WHO-defined IC domains.
• Harmonization of IC operationalization across culturally and socioeconomically diverse countries (UK and Brazil) was a key methodological objective of the study.