Association Between the Cardiometabolic Index and Intrinsic Capacity and its domains in Older Adults: A Study Based on CHARLS Data

Background This study aims to investigate the association between the Cardiometabolic Index (CMI) and intrinsic capacity (IC) and its domains among older adults in China, using data from the CHARLS study. Methods Using data from 7,058 participants aged 60–80 in the 2011–2020 wave of the CHARLS cohort, this cross-sectional analysis concentrated on examining the association between CMI and IC and its domains. The total score was derived from five standardized domains: cognitive, psychological, vitality, locomotion, and sensory. The study utilized multiple linear regression model to investigate the link between CMI and IC as well as its domains. Stratified analyses by gender, age group, and chronic disease status were conducted to evaluate the robustness of the results. Bootstrap mediation analysis was used to test the mediating role of the vitality domain. Results In fully adjusted models, the CMI was not significantly associated with overall IC (β = − 0.011, P  = 0.344). However, domain-specific analyses revealed divergent associations: CMI exhibited significant positive correlations with the cognitive domain (β = +0.084, P  < 0.001) and the psychological domain (β = +0.036, P  = 0.002), but a pronounced negative association with the vitality domain (β = − 0.128, P  < 0.001). No statistically significant relationships were observed between CMI and either the locomotion or sensory domains. Mediation analysis further demonstrated that CMI exerted a significant negative indirect effect on IC through its detrimental impact on vitality (ACME = − 0.0676), while simultaneously showing a significant positive direct effect on IC (ADE = + 0.0570, P  < 0.001). These opposing pathways effectively offset one another, yielding a non-significant total effect. Subgroup analyses corroborated these findings, demonstrating robustness across strata. Conclusions The association between the CMI and IC in older adults demonstrates a nuanced, bidirectional relationship. Elevated CMI is linked to a reduction in overall functional reserve—particularly through diminished vitality—yet paradoxically shows a positive association with cognitive and psychological domains of IC. This duality highlights the limitations of relying on single composite metrics in geriatric health evaluation and underscores the necessity of adopting a multidimensional framework that accounts for the trade-offs and dynamic interplay among distinct components of IC.