Association Between Socioeconomic Status and Mortality Risk in CKM Stage 0–3 Patients: Analysis of Inflammatory Mediation

Objective This study aimed to investigate whether socioeconomic status (SES) influences the risk of all‐cause and cardiovascular mortality among patients with cardiovascular–kidney–metabolic (CKM) syndrome stages 0–3 through the systemic inflammation response index (SIRI). The investigation utilized a nationally representative sample from the U.S. National Health and Nutrition Examination Survey (NHANES) database and employed mediation analysis for systematic assessment. Methods Data were derived from NHANES surveys conducted between 1999 and 2018, enrolling adults who met the classification criteria for CKM stages 0–3. SES was defined by the stratified family income‐to‐poverty ratio (PIR), with SIRI serving as the mediator. The primary outcomes were all‐cause and cardiovascular mortality. Methodological approaches included weighted multivariable Cox regression, subgroup analyses, sensitivity analyses, and bootstrap‐based mediation analysis. Results The study included 15,623 participants who were followed for a mean duration of 115 months, during which 1788 all‐cause deaths and 405 cardiovascular deaths were recorded. After comprehensive adjustment for potential confounders, each unit increase in PIR was associated with a significantly reduced risk of all‐cause mortality (HR = 0.88, 95% CI: 0.84–0.92) and cardiovascular mortality (HR = 0.85, 95% CI: 0.77–0.95). Participants in the high SES group demonstrated substantially lower risks for both all‐cause mortality (HR = 0.57, 95% CI: 0.47–0.69) and cardiovascular mortality (HR = 0.50, 95% CI: 0.34–0.73) compared to their low SES counterparts. Notably, mediation analysis revealed that SIRI accounted for 63.67% of the association between SES and all‐cause mortality, and 60.45% of the association between SES and cardiovascular mortality after full adjustment for confounding variables. Conclusion SES significantly impacts the risk of all‐cause and cardiovascular mortality among patients with CKM stages 0–3, with a substantial portion of this effect mediated through systemic inflammation as measured by SIRI. These findings suggest that comprehensive interventions targeting both socioeconomic conditions and chronic inflammation may effectively enhance long‐term health outcomes in this vulnerable population.