Background Cardiovascular-Kidney-Metabolic (CKM), introduced by the American Heart Association (AHA) in October 2023, is a progressive disorder, with individuals in stages 0-3 being the primary focus for early prevention. However, the association between CKM syndrome staging model and cardiovascular disease (CVD) risk remains unvalidated. Additionally, the cardiometabolic index (CMI) has emerged as a potential predictor of CVD, but large-scale cohort studies in CKM stages 0 to 3 are lacking. Methods This study utilized data from the China Health and Retirement Longitudinal Study (CHARLS), which established a baseline cohort between 2011 and 2012, with follow-ups through 2020 (n=7,196). Multivariable Cox models were used to assess the relationship between CMI quartiles and the incidence of CVD, as well as the relationship between CKM stages and CVD incidence. Additionally, restricted cubic splines (RCS) were employed to explore the non-linear association between CMI and CVD risk. To further investigate the associations of CMI quartiles and CKM stages (0–3) with CVD incidence, we conducted two sets of subgroup analyses. Sensitivity analyses excluded early CVD cases (2013) to minimize reverse causality. Results During the follow-up, 1,806 participants developed CVD, with an overall incidence rate of 25.10%. Five Cox models demonstrated a positive association between CMI quartiles and CVD risk, with the highest risk observed in the quartile 4 (Q4) group (HR: 1.287, 95% CI: 1.029-1.611). A non-linear relationship between CMI and CVD risk was identified (P-non-linear = 0.013). The highest incidence (29.57%) and risk (HR: 1.605, 95% CI: 1.230-2.094) were observed in stage 3 of CKM syndrome, with CVD risk progressively increasing with higher stages (P for trend < 0.05). Subgroup analyses revealed no significant interactions (P for interaction > 0.05). Sensitivity analyses confirmed the robustness of the primary findings. Conclusions In a population with CKM syndrome stages 0-3, CMI quartiles are significantly positively associated with the risk of CVD. CMI may serve as an important indicator for early detection of high CVD-risk individuals, enabling preventive intervention. Higher CKM stages are associated with greater CVD risk, supporting the validity of the AHA staging model.

Cardiovascular-Kidney-Metabolic Syndrome, Cardiovascular Disease, Cardiometabolic Index, Visceral Adipose Tissue, China Health and Retirement Longitudinal Study, Restricted Cubic Splines