Intrinsic capacity trajectory and hip fracture risk in Chinese middle-aged and older adults: a 10-year retrospective cohort study

Abstract Hip fracture is a key global health challenge with an estimated incidence of 26 million new cases by 2050. Although the World Health Organization 's Intrinsic capacity (IC) framework provides a comprehensive approach to healthy ageing assessment, its relationship with hip fracture risk remains explored. To investigate the longitudinal association between intrinsic capacity trajectories and hip fracture risk in middle-aged and elderly Chinese. This retrospective cohort study used data from the China Health and Retirement Longitudinal Study (CHARLS) to follow 10,272 subjects aged ≥ 45 years over a 10-year period (2011–2020). We assessed intrinsic capacity in five domains: Locomotion, Sensory, Vitality, Psychological capacity, Cognitive function, scored from 0 to 10. Group-based trajectory modeling identified different intrinsic capacity patterns from 2011–2015. Cox regression models estimated hazard ratios (HR) for hip fracture risk. During the follow-up period, 408 participants (4.0%) developed hip fractures. Each 1-point increase in baseline Intrinsic capacity score was associated with a 14% reduction in the risk of hip fracture (HR = 0.86, 95% CI: 0.81 – 0.91). Four different intrinsic capacity trajectories were identified: High-stable (15.1%), Moderate-stable (47.0%), Moderate-declining (33.8%), and Low-declining (3.9%). In the fully adjusted model (Model III), Moderate-stable, Moderate-declining, and Low-declining showed a significantly higher risk of hip fracture compared with the High-stable trajectory group (HR = 2.48, 95% CI: 1.13–5.48; HR = 3.52, 95% CI: 1.60–7.74; and HR = 3.43, 95% CI: 1.32–8.94, respectively). Intrinsic capacity showed strong predictive value for hip fracture risk, with trajectory decline significantly increasing fracture susceptibility. These findings support the implementation of Intrinsic capacity based personalized fracture prevention screening strategies in the elderly population.