Association between the cardiometabolic index and intrinsic capacity and its domains in older adults: a study based on CHARLS data

BACKGROUND: This study aimed to examine the association between the cardiometabolic index (CMI) and intrinsic capacity (IC) and its domains among older adults in China using data from the China Health and Retirement Longitudinal Study (CHARLS). METHODS: Using data from 7,058 participants aged 60-80 years from the 2011-2020 waves of CHARLS, this cross-sectional study examined the association between CMI and IC and its domains. The total IC score was derived from five standardized domains: cognitive, psychological, vitality, locomotion, and sensory. Multiple linear regression models were used to assess the associations between CMI and IC_total as well as its domains. Stratified analyses by sex, age group, and chronic disease status were conducted to examine the robustness of the findings. In addition, an exploratory mediation analysis was performed to assess whether the observed association between CMI and IC was statistically consistent with an indirect association through vitality. RESULTS: In the crude model, higher CMI was significantly associated with lower IC_total scores (β = -0.049, P < 0.001). In the age- and sex-adjusted model, CMI was positively associated with the cognitive domain (β = 0.084, P < 0.001) and the psychological domain (β = 0.036, P = 0.002), and inversely associated with vitality (β = -0.128, P < 0.001), while no significant association was observed with IC_total. After further adjustment for available sociodemographic and health-related covariates, higher CMI was significantly associated with lower IC_total (β = -0.060, 95% CI: -0.084 to -0.037, P < 0.001) and lower vitality (β = -0.144, 95% CI: -0.167 to -0.121, P < 0.001), whereas the associations with the cognitive, psychological, locomotion, and sensory domains were no longer statistically significant. Mediation analysis suggested that the observed association between CMI and IC was statistically consistent with an indirect association through vitality; however, this finding should be interpreted cautiously given the cross-sectional design. CONCLUSIONS: Among older Chinese adults, higher CMI was independently associated with lower overall intrinsic capacity and lower vitality after adjustment for available covariates. The positive associations with the cognitive and psychological domains observed in simpler models were attenuated after fuller adjustment, suggesting that these associations may be partly explained by confounding. Overall, vitality appears to be the IC domain most consistently associated with cardiometabolic burden in later life.