Comparative Analysis of Intrinsic Capacity Impairments, Determinants, and Clinical Consequences in Older Community-Dwellers in Japan and Taiwan: Longitudinal Studies Showing Shared Traits and Distinct Presentations

Objectives: Despite the recognized impact of intrinsic capacity (IC) impairment on healthy aging, international comparisons in different sociocultural contexts are scarce. This study aimed to compare IC impairment among community-dwelling older adults in Japan and Taiwan to explore the context of healthy aging in different countries. Design: Comparative observational study. Setting: National Institute for Longevity Sciences-Longitudinal Study of Aging (NILS-LSA) in Japan and Longitudinal Aging Study of Taipei (LAST) in Taiwan. Participants: 794 individuals (age range, 60.0–86.5 years) from NILS-LSA and 1,358 (60.0–96.7 years) from LAST. Measurements: IC impairment was evaluated across the domains of locomotion, cognition, vitality, sensory capacity, and psychological well-being. Participants were categorized as having impaired IC or healthy. We investigated associations between IC impairment, falls, and all-cause mortality. Results: IC impairment was present in 54.9% and 37.3% of participants in the NILS-LSA and LAST cohorts, respectively. Male NILS-LSA participants with impaired IC (odds ratio [OR]:1.50, 95% confidence interval [CI]:1.03–2.20), with hearing loss (OR:1.98, 95% CI:1.00–3.90) were more likely to fall. In LAST, impaired locomotion (OR:2.14, 95% CI:1.46–3.14) increased the risk of falls. Men with impaired IC (hazard ratio [HR]; 2.14, 95% CI.10–4.15) and visual impairment (HR:2.21, 95% CI:1.15–4.25) and women with impaired psychological well-being (HR:4.94, 95% CI:1.28–18.97) in the NILS-LSA cohort had greater risk for all-cause mortality; however, this was not shown for LAST participants. Conclusion: The prevalence and distribution of IC impairment and associated biomarkers differed significantly between participants in Japan and Taiwan. However, the associations with adverse outcomes remained similar, emphasizing the need for tailored interventions for healthy aging.