Background: Intrinsic capacity (IC) is a core component of the World Health Organization’s healthy ageing framework. Yet, despite multiple validations of IC across various settings, there is still a lack of longitudinal cross-national analysis. We used data from the Survey of Health, Ageing, and Retirement in Europe (SHARE) to validate the IC concept, describe variance between key demographic groups, and create population centile curves across 15 countries.

Methods: We analysed data from 64,872 participants from SHARE Wave 5 (2013) and determined subsequent care dependence in Wave 6 (2015). The methodologies employed included Structural Equation Modelling, bifactor analysis, and path analysis. Construct validity was tested through multiple linear regression, while predictive validity was assessed using mediation analysis. Centile curves were established using the GAMLSS method.

Findings: Our analysis revealed IC's structure as one general factor and five subdomains. Regression linked IC to age, gender, education, multimorbidity, and socio-economic status. Mediation analysis indicated that IC predicts subsequent declining performance in daily activities. We observed significant variations in IC scores between genders and across countries, allowing us to construct centile curves for IC by gender and country. Lower socio-economic status was correlated with lower scores in both males and females.

Interpretation: IC is a valid, reliable measure that effectively captures individual-level aspects of the functional ability of older adults. The centile curves we have developed show that IC has the potential to serve as a benchmark for health status in older populations.