Endothelial activation and stress index score is a predictor for all-cause and cardiovascular mortality in individuals with cardiovascular disease: a national cross-sectional study

Background Endothelial dysfunction plays a crucial role in the pathogenesis of cardiovascular disease (CVD). Although the Endothelial Activation and Stress Index (EASIX) predicts mortality in endothelial dysfunction-related conditions, its role in CVD mortality risk remains unclear. Methods This study examines the link between EASIX and mortality in 1,881 CVD patients from seven National Health and Nutrition Examination Survey (NHANES) cycles (2003–2016), with mortality data obtained from the National Death Index. Restricted cubic spline (RCS) regression analyzed the relationship between EASIX and mortality, while maximally selected rank statistics method (MSRSM) determined the optimal EASIX cutoff. Weighted multivariable Cox regression models assessed the relationship between EASIX and all-cause and cardiovascular mortality. Results Among the 1,881 patients, 830 (44.1%) died, with 273 (14.5%) from cardiovascular causes and 557 (29.6%) from non-cardiovascular causes. RCS analysis demonstrated a positive correlation between EASIX and both all-cause and cardiovascular mortality, with each 1-unit increase in EASIX corresponding to a 26% and 29% rise in mortality risk, respectively. MSRSM categorized patients into higher (>0.79) and lower (≤0.79) EASIX groups. Higher EASIX in CVD patients was significantly associated with an increased risk of all-cause (HR 1.54, 95% CI 1.22-1.94) and cardiovascular mortality (HR 1.67, 95% CI 1.09-2.57). Time-dependent receiver operating characteristic analysis yielded area under the curve for 1-, 3-, 5-, and 10-year survival of 0.71, 0.68, 0.66, and 0.68 (all-cause) and 0.77, 0.74, 0.73, and 0.72 (cardiovascular). Conclusions Elevated EASIX is independently associated with increased all-cause and cardiovascular mortality in CVD patients, indicating its potential as a valuable clinical biomarker.