Impact of cardiometabolic index on cardiovascular-kidney-metabolic syndrome stage progression: a nationwide prospective cohort study

Background The Cardiovascular-Kidney-Metabolic (CKM) syndrome is a newly defined concept introduced by the American Heart Association, underscoring the intricate interconnections among metabolic, renal and cardiovascular disease (CVD). Cardiometabolic index (CMI) is an indicator of insulin resistance and studies have shown a correlation between CMI and CVD. However, its impact on CKM staging and prognosis in populations of CMI remains unknown. Methods Participants with definite CKM stages from the China Health and Retirement Longitudinal Study (CHARLS) conducted in Mainland China were included for analysis. CMI was computed utilizing the following formula: CMI = [waist circumference (cm) / height (cm)] × [triglycerides (mg/dL) / high-density lipoprotein cholesterol (mg/dL)]. Outcomes were defined as the progression of CKM stages from Wave 1 to Wave 3 for participants in different CKM stages at baseline. Binary logistic regression and restricted cubic spline (RCS)regression analyses were conducted to evaluate the relationship between CMI and CKM stage progression. Results A total of 4,080 participants were analyzed, with an average age of 59.02 years and 46.30% male.Except for the CKM stage 0 cohort, an elevated CMI was significantly associated with the progression of CKM stages in the CKM stages 0-1, 0-2, and 0-3 populations. As a continuous variable, the adjusted OR for progression to CKM stages 2-4 was 1.40 (95% CI: 1.09-1.80) for those at baseline stages 0-1. For stages 3-4 among those at stages 0-2, OR was 1.17 (95% CI: 1.05-1.29), and for stage 4 among those at stages 0-3, OR was 1.17 (95% CI: 1.03-1.32). As a categorical variable, adjusted ORs for Q2, Q3, and Q4 compared to Q1 were 1.53 (95% CI: 0.99-2.38), 2.05 (95% CI: 1.34-3.18), and 1.76 (95% CI: 1.14-2.74) respectively for progression to CKM stages 2-4 among those at baseline stages 0-1. For stages 3-4 among those at stages 0-2, ORs were 1.35 (95% CI: 1.10-1.66), 1.30 (95% CI: 1.05-1.60), and 1.63 (95% CI: 1.33-2.00) respectively. For stage 4 among those at stages 0-3, ORs were 1.47 (95% CI: 1.14-1.91), 1.52 (95% CI: 1.18-1.97), and 1.70 (95% CI: 1.32-2.20) respectively.Significant positive non-linear associations were observed between elevated CMI levels and an increased risk of progression to advanced CKM stages in the CKM stages 0-1, 0-2, and 0-3 populations(all p-values for overall < 0.05, all p-values for non-linear > 0.05). Conclusions This cohort study demonstrated a positive linear association between CMI and increased risk of progression to advanced CKM stages. This finding suggests that enhanced assessment of CMI may provide a more convenient and effective tool for evaluating the progression of CKM stages.