Abstract
BACKGROUND: Intrinsic capacity (IC) is vital to the World Health Organization's healthy ageing framework. This study aims to develop an IC assessment model, and identify its longitudinal trajectories and related factors in old persons. METHODS: This was a 15-year three-wave prospective cohort study of the 10/66 dementia series researches in Beijing, China. Totally 2 156 community-dwelling old persons aged 65 years and over were included at baseline to develop an IC assessment model, with 474 completing follow-up surveys for IC trajectory identification. IC was assessed using 11 items of the five domains and bifactor-multidimensional item response theory model. The group-based trajectory model and multivariate logistic regression model were employed to identify longitudinal trajectories and related factors of IC. RESULTS: Three IC trajectories were identified as low baseline IC with rapid descending trajectory (11.39%), medium baseline IC with moderate descending trajectory (75.53%), and high baseline IC with slight descending trajectory (13.08%). Compared to the "slight descending trajectory", aged 75 years and over (aOR: 9.48), female (aOR: 4.75), and unmarried/non-cohabiting (aOR: 4.73) were positively associated with the "rapid descending trajectory". Completed secondary school/higher education (aOR: 0.08; aOR: 0.27), more vegetables/fruits intake (aOR: 0.91; aOR: 0.94), and private restricted support network (aOR: 0.17; aOR: 0.37) were negatively associated with the "rapid descending trajectory" and "moderate descending trajectory". CONCLUSIONS: Community-dwelling old persons in Beijing exhibit three IC trajectories, with the majority showing moderate descending trajectory. Interventions should address gender or education inequities and modifiable factors like diet and social support to mitigate IC decline.