Predictive Value of Remnant Cholesterol Inflammatory Index for Cardiovascular-Kidney-Metabolic Syndrome Progression: A Prospective Cohort Study

Background Remnant cholesterol (RC) is an established risk factor for cardiovascular-kidney-metabolic (CKM) syndrome progression. However, the combined effect of RC and high-sensitivity C-reactive protein (hs-CRP) remains unclear. This study evaluated the association between the remnant cholesterol inflammatory index (RCII) and CKM progression risk. Methods Data from the China Health and Retirement Longitudinal Study (CHARLS) were analyzed. Logistic regression models were employed to investigate the association between the baseline RCII and advanced CKM stages. Kaplan‒Meier analysis was conducted to assess the cumulative incidence of cardiovascular disease (CVD) across RCII quartiles in individuals with CKM stages 0–3. Cox regression models were used to examine the associations of the baseline and cumulative RCII with the risk of new-onset CVD among individuals with CKM stages 0–3. Results Each standard deviation (SD) increase in the RCII was associated with a 28% greater risk of advanced CKM stages (OR: 1.28, 95% CI: 1.21–1.35). The cumulative incidence of CVD progressively increased across RCII quartiles, from 17.02% in Q1 to 25.75% in Q4. After full adjustment, compared with that in RCII Q1, CVD risk was 19% greater in Q3 (HR: 1.19, 95% CI: 1.02–1.39) and 30% greater in RCII Q4 (HR: 1.30, 95% CI: 1.11–1.51). Participants with cumulative RCII levels that exceeded 36.14 had a significantly increased risk of new-onset CVD (HR: 1.462, 95% CI: 1.102–1.939). Conclusions Higher baseline and cumulative RCII were associated with increased CVD risk in participants with CKM stages 0 – 3. Early intervention in those with elevated RCII may help prevent CKM progression.