Abstract
BACKGROUND: The dietary inflammatory index (DII) quantifies the inflammatory potential of an individual's diet and has been linked to various chronic diseases. However, the association between DII and the severity of cardiovascular-kidney-metabolic (CKM) syndrome, as well as its impact on long-term mortality, remains insufficiently understood. METHODS: We analyzed data from 17,412 adults enrolled in the National Health and Nutrition Examination Survey (NHANES) between 1999 and 2018. Dietary Inflammatory Index (DII) scores were derived from 24-hour dietary recall data, and CKM syndrome was categorized according to standardized staging criteria. Baseline characteristics were compared across DII quartiles and CKM stages. Multivariable logistic regression was used to assess the association between DII and advanced CKM (Stages 3-4), while Cox proportional hazards models estimated hazard ratios (HRs) for all-cause and cardiovascular mortality. Potential dose-response relationships were explored using restricted cubic spline analyses. RESULTS: Participants with higher DII scores demonstrated less favorable sociodemographic and metabolic characteristics. Each one-point increment in DII was associated with a 6% increase in the odds of advanced CKM syndrome (adjusted odds ratio [OR]: 1.06; 95% confidence interval [CI]: 1.02-1.11). Compared to individuals in the lowest DII quartile, those in the highest quartile had a 36% greater Likelihood of advanced CKM. Over a median follow-up of 118 months, elevated DII scores were significantly linked to increased risks of all-cause mortality (hazard ratio [HR]: 1.073; 95% CI: 1.046-1.100) and cardiovascular mortality (HR: 1.073; 95% CI: 1.023-1.124), with dose-response relationships consistent with linearity. Subgroup analyses revealed that these associations were particularly pronounced among women (in relation to CKM severity), former smokers and individuals without hypertension (for all-cause mortality), and participants with higher educational attainment (for cardiovascular mortality). CONCLUSIONS: A pro-inflammatory dietary pattern, as indicated by higher DII scores, is independently associated with greater severity of CKM syndrome and elevated long-term mortality. These findings highlight the potential of dietary inflammation as a modifiable target for CKM prevention and management.