Cardiometabolic index (CMI) and sarcopenia as predictors of all-cause and cardiovascular mortality in chronic kidney disease: a NHANES-based cohort study

The Cardiometabolic Index (CMI) reflects visceral adiposity and lipid dysregulation, while sarcopenia indicates skeletal muscle depletion, both representing metabolic and functional decline in chronic kidney disease (CKD). This study aimed to investigate the impact of CMI and sarcopenia, as well as their integration into a metabolico-muscular composite risk model, on all-cause and cardiovascular mortality in CKD patients. Based on data from the National Health and Nutrition Examination Survey spanning 1999-2006 and 2011-2018, a total of 1,886 CKD patients were included. Kaplan-Meier survival analysis, multivariable Cox proportional hazards models, restricted cubic spline regression, and subgroup analyses were employed for assessment, while time-dependent receiver operating characteristic analysis was used to evaluate predictive performance. Results showed that patients with both high CMI and sarcopenia had the lowest survival rate. After multivariable adjustment, Cox regression demonstrated that patients in the highest CMI quartile had significantly increased risks of all-cause mortality (HR = 2.25, 95% CI: 1.35-3.73) and cardiovascular mortality (HR = 4.03, 95% CI: 1.52-10.70). Sarcopenia was also associated with increased risks of both mortality types (all-cause: HR = 1.27, 95% CI: 1.10-2.49; cardiovascular: HR = 1.12, 95% CI: 1.06-2.21). Further analysis identified nonlinear relationships between CMI and both all-cause and cardiovascular mortality, regardless of sarcopenia status. This longitudinal cohort study demonstrates that elevated CMI and sarcopenia are independently associated with increased mortality risk in CKD patients, with the highest risk observed when both conditions coexist. Therefore, this study positions CMI and sarcopenia as prognostic biomarkers for mortality risk stratification in CKD.