Yafei Si, Katja Hanewald, Shu Chen, Bingqin Li, Hazel Bateman and John R. Beard
Background: Maintaining and optimising intrinsic capacity (IC) across a person’s life course is a core component of the World Health Organization’s model of healthy ageing. However, the contribution of cumulative health inequalities over time to subtle changes in IC in late life is not well understood.
Methods: We included 21,783 participants aged 45+ from the China Health and Retirement Longitudinal Study and calculated a validated prognostic value of IC. We included eleven early-life factors to investigate their direct influence on IC over thirty years later and cumulative influence through four current socioeconomic factors. We used multivariable linear regression and concentration index decomposition to investigate the contributions of each determinant to IC inequalities. Mediation analysis identified the direct and cumulative contribution of early-life factors.
Results: Participants with an advantaged environment in childhood and a higher current socioeconomic position had a significantly higher IC score. This inequality was greatest for cognitive capacity and sensory capacity. Overall, early-life factors directly explained 13.92% (95% CI: 12.07% to 15.77%) of IC inequalities, while 28.57% (95% CI: 28.19% to 28.95%) of IC inequalities were explained through the cumulative effects of socioeconomic inequalities over a person’s life course.
Conclusion: In China, unfavourable early-life factors appear to directly decrease late-life health status, particularly cognitive and sensory capacities rather than locomotor functioning, psychological capacity or homeostasis, and these effects are exacerbated by the cumulative socioeconomic inequalities over a person’s life course. Interventions in early life and subsequently across the life course may be effective in reducing these disparities.
Keywords: intrinsic capacity, healthy ageing, life course inequality, cognition, China