Association between the oxidative balance score and all-cause and cardiovascular mortality in patients with cardiovascular-kidney-metabolic syndrome——a retrospective cohort study from the NHANES

BACKGROUND: The American Heart Association recently introduced the concept of Cardiovascular-Kidney-Metabolic (CKM) syndrome, underscoring the intricate interplay between metabolic, renal, and cardiovascular diseases. The oxidative balance score (OBS) serves as a comprehensive metric to quantify oxidative stress-related exposures. This study investigates the association between OBS and both all-cause and cardiovascular mortality in these individuals. METHODS: The study cohort analyzed 15,357 CKM patients from the 2003 to 2018 National Health and Nutrition Examination Survey database. Kaplan-Meier survival analysis, multivariable Cox regression models, restricted cubic splines, and subgroup analyses were employed to evaluate the relationship between OBS and mortality risk. RESULTS: There were 1,759 all-cause deaths and 459 cardiovascular deaths. Kaplan-Meier analysis revealed that individuals in the highest quartile of OBS (Q4) had the lowest all-cause and cardiovascular mortality rates, whereas the lowest quartile (Q1) exhibited the highest mortality rates (p < 0.001). In fully adjusted models, multivariable Cox regression showed that each one-unit increase in OBS was associated with a 1.1% reduction in the risk of all-cause mortality and a 1.6% reduction in cardiovascular mortality (HR 0.989, 95% CI 0.982-0.996, p = 0.003, HR 0.984, 95% CI 0.970-0.998, p = 0.026, respectively). Compared to Q1, individuals in Q4 had significantly lower risks of both all-cause mortality (HR 0.723, 95% CI 0.607-0.861, p < 0.001) and cardiovascular mortality (HR 0.642, 95% CI 0.439-0.938, p = 0.022). Subgroup analyses indicated that the association between OBS and reduced mortality risk was particularly pronounced among individuals with higher educational attainment, non-chronic kidney disease, high poverty income ratio individuals and more advanced stages of CKM syndrome. In addition, restricted cubic spline modelling identified a graded inverse association between oxidative balance scores (OBS) and mortality risk. This suggests a dose-dependent protective effect of higher OBS, consistently observed across diverse demographic strata and clinical severity levels. CONCLUSION: Higher OBS is linked to reduced all-cause and cardiovascular mortality in CKM patients.