Multi-Trajectories of Intrinsic Capacity Decline and Their Impact on Age-Related Outcomes: A 20-Year National Longitudinal Cohort Study

The existence of intrinsic capacity (IC) subtypes and their distinct impacts on age-related outcomes remain unexplored. This study sought to investigate IC impairment trajectories across domains and their associations with the risk of age-related outcomes, including falls, functional limitations, reduced quality of life (QoL) and mortality at 4- and 8-year follow-ups. The study sample comprised 1,782 older adults residing in the community from the Taiwan Longitudinal Study on Ageing (TLSA). Utilizing group-based multitrajectory modeling, distinct subtypes of IC decline trajectories across various domains were identified. Cox proportional hazard models and multivariable logistic regression analyses were employed to assess the associations between the identified subtypes and age-related outcomes. We identified four subtypes of IC decline: robust with mild decline (n=902), hearing loss with cognitive decline (n=197), physio-cognitive decline (PCD) with depression (n=373), and severe IC decline (n=310). Over the 4-year study period, compared to the robust with mild decline group, hearing loss with cognitive decline group exhibited a significantly higher risk of diminished QoL (OR=2.53 [1.66-3.86], p<0.01), whereas those in the PCD with depression group experienced an elevated risk of falls (OR=1.62 [1.18-2.23], p<0.01), as well as functional limitation (OR=2.61 [1.81-3.75], p<.01). Individuals in the severe IC decline group faced a substantially increased risk of all outcomes of interest. Distinct subtypes of IC decline across different domains have varying impacts on age-related outcomes, highlighting the need for a personalized approach to promote healthy ageing at the population level, while further investigation into specific pathophysiological mechanisms is warranted as well.