A Multidimensional Biomarker Model of Vitality and Its Associations With Intrinsic Capacity and Frailty

BackgroundThe World Health Organisation has identified intrinsic capacity (IC) as a key determinant of healthy ageing. Within the IC framework, vitality reflects physiological reserve arising from neuromuscular, metabolic and inflammatory/stress-response systems. However, this multidomain physiological construct has not been empirically validated, and vitality is often operationalised using nutritional assessments alone.ObjectivesWe evaluated a biomarker-derived vitality construct and examined its associations with IC domains and frailty, compared to nutritional measures.MethodsCross-sectional analysis of 300 community-dwelling, functionally-independent older adults (mean age 67.4±7.1; 69% female) was conducted using exploratory (EFA) and confirmatory factor analyses (CFA) to characterise the latent structure of biomarker-defined vitality. Factor scores were examined for associations with IC domains, composite IC and frailty using linear regression, compared with the Mini Nutritional Assessment–Short Form (MNA-SF).ResultsEFA supported a multidimensional structure with biomarkers clustering into neuromuscular, metabolic and inflammatory domains. CFA supported a correlated three-factor model for vitality; while a bifactor model showed superior global fit, general factor dominance was limited (ECV=0.28; ωH=0.26), with most variance at the domain level. Higher neuromuscular vitality was associated with greater composite IC (β=1.39, 95%CI 0.25 to 2.54) and cognitive capacity (β=1.74, 95%CI 0.52 to 2.95). A better metabolic vitality profile was associated with higher locomotor capacity (β=1.74, 95%CI 0.58 to 2.91), while a more favourable inflammatory vitality profile was associated with higher locomotor capacity (β=1.33, 95%CI 0.09 to 2.57) and reduced frailty (β = −0.11, 95%CI −0.22 to −0.022). In contrast, MNA-SF scores were associated only with lower frailty (β=−0.09, 95%CI −0.17 to −0.004), and not with IC.ConclusionsVitality is better represented as a multidimensional, physiological construct than by nutrition-based measures alone. Distinct biomarker-derived vitality domains were associated with IC and frailty, supporting its role in characterising physiological determinants of healthy ageing. Longitudinal research is required to establish its prognostic value.