Prognostic value of the cardiometabolic index for mortality in patients with cardiometabolic syndrome: A longitudinal analysis based on NHANES data

BACKGROUND AND OBJECTIVE: Cardiometabolic syndrome (CMS) is a major risk factor for cardiovascular diseases and type 2 diabetes mellitus, necessitating reliable mortality risk prediction tools. The Cardiometabolic Index (CMI), integrating waist-to-height ratio and triglyceride-to-high-density lipoprotein cholesterol ratio, correlates closely with metabolic dysregulation. This study evaluated CMI's prognostic value for all-cause and cause-specific mortality in CMS patients. METHODS AND RESULTS: A cohort of 5476 adult CMS patients from the 1999-2018 National Health and Nutrition Examination Survey (NHANES) was analyzed. CMI was calculated as waist-to-height ratio × (triglyceride/HDL-cholesterol) and log-transformed. Cox proportional hazards regression, restricted cubic spline analyses, sensitivity analyses, and subgroup assessments were applied. Over a median 95-month follow-up, 1376 all-cause, 474 cardiovascular, and 79 diabetes-related deaths were recorded. Fully adjusted models showed a positive association between CMI and all-cause mortality (per SD increase, HR = 1.02, P = 0.033) with a significant dose-response relationship (P = 0.001). CMI was nonlinearly linked to diabetes-related mortality (per unit increase, HR = 1.07, P = 0.034), with risk surging when CMI exceeded 1.67. No significant correlation emerged for cardiovascular mortality. Subgroup analysis confirmed enhanced CMI predictive performance in high-risk populations, and sensitivity analyses verified findings robustness. CONCLUSION: CMI acts as a novel biomarker for all-cause and diabetes-related mortality risk in CMS patients, reflecting gradient risks across metabolic dysregulation subgroups and supporting risk stratification. Further prospective studies are warranted to validate its clinical utility.